Publications of year 2007

Books and proceedings

1. Alessandro Ferretti, Andrea Monti-Guarnieri, Claudio Prati, Fabio Rocca, and Didier Massonnet. InSAR Principles: Guidelines for SAR Interferometry Processing and Interpretation, Part A: Interferometric SAR image processing and interpretation. ESA, 2007. Keyword(s): SAR Processing, InSAR, SAR Interferometry, Interferometry, ESA, ESA-TM-19.

   Abstract:

   Part A is for readers with a good knowledge of optical and microwave remote sensing, to acquaint them with interferometric SAR image processing and interpretation.

   
   

   @Book{InSAR_ESA_TM-19_2007PartA,
   author = {Alessandro Ferretti and Andrea Monti-Guarnieri and Claudio Prati and Fabio Rocca and Didier Massonnet},
   publisher = {ESA},
   title = {{InSAR} Principles: Guidelines for {SAR} Interferometry Processing and Interpretation, {Part A}: Interferometric SAR image processing and interpretation},
   year = {2007},
   isbn = {92-9092-233-8},
   abstract = {Part A is for readers with a good knowledge of optical and microwave remote sensing, to acquaint them with interferometric SAR image processing and interpretation.},
   file = {:InSAR_ESA_TM-19_2007PartA.pdf:PDF},
   keywords = {SAR Processing, InSAR, SAR Interferometry, Interferometry, ESA, ESA-TM-19},
   owner = {ofrey},
   pdf = {../InSAR_ESA_TM-19_ptA.pdf},
   url = {http://www.esa.int/About_Us/ESA_Publications/InSAR_Principles_Guidelines_for_SAR_Interferometry_Processing_and_Interpretation_br_ESA_TM-19},
   
   }
   




2. Alessandro Ferretti, Andrea Monti-Guarnieri, Claudio Prati, Fabio Rocca, and Didier Massonnet. InSAR Principles: Guidelines for SAR Interferometry Processing and Interpretation, Part B: InSAR processing: a practical approach. ESA, 2007. Keyword(s): SAR Processing, InSAR, SAR Interferometry, Interferometry, ESA, ESA-TM-19.

   Abstract:

   Part B provides a practical approach and the technical background for beginners with InSAR processing.

   
   

   @Book{InSAR_ESA_TM-19_2007PartB,
   author = {Alessandro Ferretti and Andrea Monti-Guarnieri and Claudio Prati and Fabio Rocca and Didier Massonnet},
   publisher = {ESA},
   title = {{InSAR} Principles: Guidelines for {SAR} Interferometry Processing and Interpretation, {Part B}: {InSAR} processing: a practical approach},
   year = {2007},
   isbn = {92-9092-233-8},
   abstract = {Part B provides a practical approach and the technical background for beginners with InSAR processing.},
   file = {:InSAR_ESA_TM-19_2007PartB.pdf:PDF},
   keywords = {SAR Processing, InSAR, SAR Interferometry, Interferometry, ESA, ESA-TM-19},
   owner = {ofrey},
   pdf = {../InSAR_ESA_TM-19_ptB.pdf},
   url = {http://www.esa.int/About_Us/ESA_Publications/InSAR_Principles_Guidelines_for_SAR_Interferometry_Processing_and_Interpretation_br_ESA_TM-19},
   
   }
   




3. Alessandro Ferretti, Andrea Monti-Guarnieri, Claudio Prati, Fabio Rocca, and Didier Massonnet. InSAR Principles: Guidelines for SAR Interferometry Processing and Interpretation, Part C: InSAR processing: a mathematical approach. ESA, 2007. Keyword(s): SAR Processing, InSAR, SAR Interferometry, Interferometry, ESA, ESA-TM-19.

   Abstract:

   Part C contains a more mathematical approach, for a deeper understanding of the interferometric process. It includes themes such as super resolution and ERS/Envisat interferometry.

   
   

   @Book{InSAR_ESA_TM-19_2007PartC,
   title = {{InSAR} Principles: Guidelines for {SAR} Interferometry Processing and Interpretation, {Part C}: {InSAR} processing: a mathematical approach},
   publisher = {ESA},
   year = {2007},
   author = {Alessandro Ferretti and Andrea Monti-Guarnieri and Claudio Prati and Fabio Rocca and Didier Massonnet},
   isbn = {92-9092-233-8},
   abstract = {Part C contains a more mathematical approach, for a deeper understanding of the interferometric process. It includes themes such as super resolution and ERS/Envisat interferometry.},
   file = {:InSAR_ESA_TM-19_2007PartC.pdf:PDF},
   keywords = {SAR Processing, InSAR, SAR Interferometry, Interferometry, ESA, ESA-TM-19},
   owner = {ofrey},
   pdf = {../InSAR_ESA_TM-19_ptC.pdf},
   url = {http://www.esa.int/About_Us/ESA_Publications/InSAR_Principles_Guidelines_for_SAR_Interferometry_Processing_and_Interpretation_br_ESA_TM-19},
   
   }
   

Articles in journal or book chapters

1. Mark Simons and Paul A. Rosen. Interferometric Synthetic Aperture Radar Geodesy. In Gerald Schubert, editor, Treatise on Geophysics, pages 391-446. Elsevier, Amsterdam, 2007. Keyword(s): SAR Processing, SAR Interferometry, Interferometry, InSAR, DInSAR, Crustal deformation, Geodesy, GPS, Radar interferometry, Displacement Mapping, Deformation Mapping, Teaching Material, Tutorial, Baseline Errors, orbital errors, Spaceborne SAR, Teaching.

   Abstract:

   Satellite-based interferometric synthetic aperture radar (InSAR) provides a synoptic high spatial resolution perspective of Earth's deforming surface, permitting one to view large areas quickly and efficiently. We review basic InSAR theory for geodetic applications and attempt to provide an overview of what processing and analysis schemes are currently used and a glimpse of what the future may hold. As part of this discussion, we present a biased view of what constitutes best practices for use of InSAR observations in geodetic modeling. Finally, we provide a basic primer on the ties between different mission design parameters and their relationship to the character of the resulting observations.

   
   

   @InCollection{simonsRosenBookSection2007InterferometricSARGeodesy,
   author = {Mark Simons and Paul A. Rosen},
   booktitle = {Treatise on Geophysics},
   publisher = {Elsevier},
   title = {Interferometric Synthetic Aperture Radar Geodesy},
   year = {2007},
   address = {Amsterdam},
   editor = {Gerald Schubert},
   isbn = {978-0-444-52748-6},
   pages = {391--446},
   abstract = {Satellite-based interferometric synthetic aperture radar (InSAR) provides a synoptic high spatial resolution perspective of Earth's deforming surface, permitting one to view large areas quickly and efficiently. We review basic InSAR theory for geodetic applications and attempt to provide an overview of what processing and analysis schemes are currently used and a glimpse of what the future may hold. As part of this discussion, we present a biased view of what constitutes best practices for use of InSAR observations in geodetic modeling. Finally, we provide a basic primer on the ties between different mission design parameters and their relationship to the character of the resulting observations.},
   doi = {https://doi.org/10.1016/B978-044452748-6.00059-6},
   file = {:simonsRosenBookSection2007InterferometricSARGeodesy.pdf:PDF},
   keywords = {SAR Processing, SAR Interferometry, Interferometry, InSAR, DInSAR, Crustal deformation, Geodesy, GPS, Radar interferometry, Displacement Mapping, Deformation Mapping, Teaching Material, Tutorial, Baseline Errors, orbital errors, Spaceborne SAR, Teaching},
   owner = {ofrey},
   url = {http://www.sciencedirect.com/science/article/pii/B9780444527486000596},
   
   }
   




2. R. Bamler, F. Meyer, and W. Liebhart. Processing of Bistatic SAR Data From Quasi-Stationary Configurations. IEEE Trans. Geosci. Remote Sens., 45(11):3350-3358, November 2007. Keyword(s): SAR Processing, Bistatic SAR, Earth surface, NuSAR approach, bistatic SAR data processing, curved orbit, equivalent velocity approximation, hyperbolic range function, quasistationarity restriction, quasistationary configuration, radar receiver, radar transmitter, range Doppler domain, synthetic aperture radar, time-domain post focusing, time-domain prefocusing, transfer functions, velocity vector, data acquisition, geophysical signal processing, geophysical techniques, radar signal processing, remote sensing by radar, synthetic aperture radar, transfer functions.

   Abstract:

   Standard synthetic aperture radar (SAR) processing algorithms use analytically derived transfer functions in the 2D frequency and range/Doppler domains. These rely on the assumption of hyperbolic range histories of monostatic SARs with straight flight paths. For bistatic SARs, the range histories are no longer hyperbolic, and simple analytic transforms do not exist. This paper offers two solutions for bistatic SAR data processing under the restriction of quasi-stationarity, i.e., sufficiently equal velocity vectors of transmitter and receiver. 1) Moderately bistatic configurations can be handled satisfactorily by using hyperbolic range functions with a modified velocity parameter, which is a solution already well known for the accommodation of curved orbits in the monostatic case. This equivalent velocity approach is shown to be of surprising range of validity even for pronounced bistatic situations. It is not to be confused with the equivalent monostatic flight path approximation, which is shown to be inapplicable for any practical case. 2) With increasing separation of transmitter and receiver, the equivalent velocity approximation deteriorates. To cope with extreme bistatic configurations, a general approach named NuSAR is proposed, where the involved transfer functions are replaced by numerically computed ones. This paper describes how the transfer functions are computed from the given orbits and the shape of the Earth surface. In any of these two cases, the bistatic SAR data can be processed by standard SAR processors; only the conventional transfer functions need to be replaced. Neither are there time-domain prefocusing or post focusing steps required nor complicated mathematical expansions involved. The presented algorithms are also applicable to very high resolution wide-swath (or squinted) SARs on curved orbits.

   
   

   @Article{BamlerMeyerLiebhart2007:BiStaticNumericSAR,
   author = {Bamler, R. and Meyer, F. and Liebhart, W.},
   journal = {IEEE Trans. Geosci. Remote Sens.},
   title = {Processing of Bistatic {SAR} Data From Quasi-Stationary Configurations},
   year = {2007},
   issn = {0196-2892},
   month = nov,
   number = {11},
   pages = {3350-3358},
   volume = {45},
   abstract = {Standard synthetic aperture radar (SAR) processing algorithms use analytically derived transfer functions in the 2D frequency and range/Doppler domains. These rely on the assumption of hyperbolic range histories of monostatic SARs with straight flight paths. For bistatic SARs, the range histories are no longer hyperbolic, and simple analytic transforms do not exist. This paper offers two solutions for bistatic SAR data processing under the restriction of quasi-stationarity, i.e., sufficiently equal velocity vectors of transmitter and receiver. 1) Moderately bistatic configurations can be handled satisfactorily by using hyperbolic range functions with a modified velocity parameter, which is a solution already well known for the accommodation of curved orbits in the monostatic case. This equivalent velocity approach is shown to be of surprising range of validity even for pronounced bistatic situations. It is not to be confused with the equivalent monostatic flight path approximation, which is shown to be inapplicable for any practical case. 2) With increasing separation of transmitter and receiver, the equivalent velocity approximation deteriorates. To cope with extreme bistatic configurations, a general approach named NuSAR is proposed, where the involved transfer functions are replaced by numerically computed ones. This paper describes how the transfer functions are computed from the given orbits and the shape of the Earth surface. In any of these two cases, the bistatic SAR data can be processed by standard SAR processors; only the conventional transfer functions need to be replaced. Neither are there time-domain prefocusing or post focusing steps required nor complicated mathematical expansions involved. The presented algorithms are also applicable to very high resolution wide-swath (or squinted) SARs on curved orbits.},
   doi = {10.1109/TGRS.2007.895436},
   keywords = {SAR Processing, Bistatic SAR, Earth surface;NuSAR approach;bistatic SAR data processing;curved orbit;equivalent velocity approximation;hyperbolic range function;quasistationarity restriction;quasistationary configuration;radar receiver;radar transmitter;range Doppler domain;synthetic aperture radar;time-domain post focusing;time-domain prefocusing;transfer functions;velocity vector;data acquisition;geophysical signal processing;geophysical techniques;radar signal processing;remote sensing by radar;synthetic aperture radar;transfer functions},
   
   }
   




3. C. Castillo-Rubio, S. Llorente-Romano, and M. Burgos-Garcia. Robust SVA method for every sampling rate condition. IEEE Transactions on Aerospace and Electronic Systems, 43(2):571 -580, April 2007. Keyword(s): SAR Processing, Apodization, Spatially Variant Apodization, SVA, SAR system, finite signal sampling rate condition, nonlinear filtering, robust SVA method, sidelobe levels signal resolution, synthetic aperture radar, target detection capability, two-dimensional generalization, variant filter, image resolution.

   Abstract:

   Linear apodization, or data weighting, is the traditional procedure to improve sidelobe levels in a finite sampled signal at the expense of resolution. New apodization methods, such as spatially variant apodization (SVA), apply nonlinear filtering to the signal in order to completely remove sidelobes without any loss of resolution. However, the results are strongly influenced by signal sampling rate. Some variations which improve results have been previously published, but sidelobe cancellation gets worse since sampling frequency is not settled at Nyquist (or a multiple). This paper presents a new and efficient technique based on SVA that drastically reduces sidelobe levels for every sampling rate condition. The algorithm is, essentially, a parameter optimization of a variant filter for each pixel of the image. A one-dimensional case and a two-dimensional generalization are presented, as well as some applications to target detection capability in a synthetic aperture radar (SAR) system.

   
   

   @Article{castilloRubioLlorenteRomanoBurgosGarcia2007:SpatiallyVariantApodization,
   Title = {Robust {SVA} method for every sampling rate condition},
   Author = {Castillo-Rubio, C. and Llorente-Romano, S. and Burgos-Garcia, M.},
   Doi = {10.1109/TAES.2007.4285354},
   ISSN = {0018-9251},
   Month = apr,
   Number = {2},
   Pages = {571 -580},
   Volume = {43},
   Year = {2007},
   Abstract = {Linear apodization, or data weighting, is the traditional procedure to improve sidelobe levels in a finite sampled signal at the expense of resolution. New apodization methods, such as spatially variant apodization (SVA), apply nonlinear filtering to the signal in order to completely remove sidelobes without any loss of resolution. However, the results are strongly influenced by signal sampling rate. Some variations which improve results have been previously published, but sidelobe cancellation gets worse since sampling frequency is not settled at Nyquist (or a multiple). This paper presents a new and efficient technique based on SVA that drastically reduces sidelobe levels for every sampling rate condition. The algorithm is, essentially, a parameter optimization of a variant filter for each pixel of the image. A one-dimensional case and a two-dimensional generalization are presented, as well as some applications to target detection capability in a synthetic aperture radar (SAR) system.},
   Journal = {IEEE Transactions on Aerospace and Electronic Systems},
   Keywords = {SAR Processing, Apodization, Spatially Variant Apodization, SVA, SAR system, finite signal sampling rate condition, nonlinear filtering, robust SVA method, sidelobe levels signal resolution, synthetic aperture radar, target detection capability, two-dimensional generalization, variant filter, image resolution} 
   }
   




4. C.F. Castillo-Rubio, S. Llorente-Romano, and C.M. Burgos-Garcia. Spatially Variant Apodization for Squinted Synthetic Aperture Radar Images. IEEE Transactions on Image Processing, 16(8):2023-2027, August 2007. Keyword(s): SAR Processing, Apodization, Spatially Variant Apodization, Nyquist rate, bidimensional finite impulse response filter, nonlinear sidelobe reduction technique, spatially variant apodization, squinted synthetic aperture radar image, synthetic aperture radar, FIR filters, radar imaging, synthetic aperture radar, Algorithms, Image Enhancement, Image Interpretation, Computer-Assisted, Information Storage and Retrieval, Radar, Reproducibility of Results, Sensitivity and Specificity.

   Abstract:

   Spatially variant apodization (SVA) is a nonlinear sidelobe reduction technique that improves sidelobe level and preserves resolution at the same time. This method implements a bidimensional finite impulse response filter with adaptive taps depending on image information. Some papers that have been previously published analyze SVA at the Nyquist rate or at higher rates focused on strip synthetic aperture radar (SAR). This paper shows that traditional SVA techniques are useless when the sensor operates with a squint angle. The reasons for this behaviour are analyzed, and a new implementation that largely improves the results is presented. The algorithm is applied to simulated SAR images in order to demonstrate the good quality achieved along with efficient computation.

   
   

   @Article{castilloRubioLlorenteRomanoBurgosGarcia2007TIP:SpatiallyVariantApodization,
   Title = {Spatially Variant Apodization for Squinted Synthetic Aperture Radar Images},
   Author = {Castillo-Rubio, C.F. and Llorente-Romano, S. and Burgos-Garcia, C.M.},
   Doi = {10.1109/TIP.2007.899603},
   ISSN = {1057-7149},
   Month = aug,
   Number = {8},
   Pages = {2023-2027},
   Volume = {16},
   Year = {2007},
   Abstract = {Spatially variant apodization (SVA) is a nonlinear sidelobe reduction technique that improves sidelobe level and preserves resolution at the same time. This method implements a bidimensional finite impulse response filter with adaptive taps depending on image information. Some papers that have been previously published analyze SVA at the Nyquist rate or at higher rates focused on strip synthetic aperture radar (SAR). This paper shows that traditional SVA techniques are useless when the sensor operates with a squint angle. The reasons for this behaviour are analyzed, and a new implementation that largely improves the results is presented. The algorithm is applied to simulated SAR images in order to demonstrate the good quality achieved along with efficient computation.},
   Journal = {IEEE Transactions on Image Processing},
   Keywords = {SAR Processing, Apodization, Spatially Variant Apodization, Nyquist rate;bidimensional finite impulse response filter;nonlinear sidelobe reduction technique;spatially variant apodization;squinted synthetic aperture radar image;synthetic aperture radar;FIR filters;radar imaging;synthetic aperture radar;Algorithms;Image Enhancement;Image Interpretation, Computer-Assisted;Information Storage and Retrieval;Radar;Reproducibility of Results;Sensitivity and Specificity} 
   }
   




5. Shane R. Cloude. Dual-Baseline Coherence Tomography. IEEE Geoscience and Remote Sensing Letters, 4(1):127-131, January 2007. Keyword(s): SAR Processing, SAR Tomography, Tomography, geophysical techniques, radar applications, singular value decomposition, vegetation, EMSL, European Microwave Signature Laboratory, dual-baseline coherence tomography, maize plants, matrix singular value decomposition, numerical stability, regularization technique, scattering mechanisms, tomograms.

   Abstract:

   In this letter, we consider a dual-baseline formulation of coherence tomography and show how practical application of the method is limited by numerical stability. To help reduce this, we propose a regularization technique based on a matrix singular value decomposition to stabilize the inversion. We then apply the new dual-baseline algorithm to ground-based radar data from the European Microwave Signature Laboratory. We consider a sample of maize plants and employ dual-baseline interferometric data to reconstruct vertical tomograms through the vegetation as a function of frequency. We use these reconstructions to interpret the primary scattering mechanisms and their polarization dependence.

   
   

   @Article{cloude2007:DualBaselineCoherentTomo,
   author = {Cloude, Shane R.},
   journal = {IEEE Geoscience and Remote Sensing Letters},
   title = {Dual-Baseline Coherence Tomography},
   year = {2007},
   issn = {1545-598X},
   month = jan,
   number = {1},
   pages = {127-131},
   volume = {4},
   abstract = {In this letter, we consider a dual-baseline formulation of coherence tomography and show how practical application of the method is limited by numerical stability. To help reduce this, we propose a regularization technique based on a matrix singular value decomposition to stabilize the inversion. We then apply the new dual-baseline algorithm to ground-based radar data from the European Microwave Signature Laboratory. We consider a sample of maize plants and employ dual-baseline interferometric data to reconstruct vertical tomograms through the vegetation as a function of frequency. We use these reconstructions to interpret the primary scattering mechanisms and their polarization dependence.},
   doi = {10.1109/LGRS.2006.885893},
   keywords = {SAR Processing, SAR Tomography, Tomography, geophysical techniques, radar applications, singular value decomposition, vegetation, EMSL, European Microwave Signature Laboratory, dual-baseline coherence tomography, maize plants, matrix singular value decomposition, numerical stability, regularization technique, scattering mechanisms, tomograms},
   owner = {ofrey},
   pdf = {../../../docs/cloude2007.pdf},
   url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4063282&isnumber=4063275},
   
   }
   




6. Ian G. Cumming and S. Li. Adding Sensitivity to the MLBF Doppler Centroid Estimator. IEEE Transactions on Geoscience and Remote Sensing, 45(2):279-292, Feb. 2007. Keyword(s): SAR Processing, Multilook Beat Frequency, MLPF, Doppler Centroid Estimation, Doppler Ambiguity Resolver, DAR, Doppler radar, fast Fourier transforms, frequency estimation, radar signal processing, remote sensing by radar, sensitivity, synthetic aperture radarDoppler ambiguity, Doppler centroid estimator, FFT, Fourier transform, MLBF algorithm, RADARSAT-1, ScanSAR, cross beating, estimation sensitivity, multilook beat frequency algorithm, range migration, target trajectory.

   Abstract:

   The multilook beat frequency (MLBF) algorithm is the Doppler centroid estimator most commonly used in practice to solve the Doppler ambiguity. However, it still makes errors, notably in medium- or low-contrast scenes. In this paper, we present two ways in which the estimation sensitivity of the MLBF algorithm can be improved. First, we give a more thorough frequency-domain explanation of how the MLBF algorithm works and explain how cross beating and range migration cause estimation difficulties. The first improvement to the algorithm replaces the fast Fourier transform (FFT)-based beat frequency estimator with a more accurate one that uses phase increments. It avoids the FFT limitations of resolution and quantization, especially when the signal is discontinuous in one range cell due to range cell migration or burst mode operation (ScanSAR). A second improvement uses range cell migration correction to straighten the target trajectories before the beat frequency estimator is applied. This has the effect of narrowing the bandwidth of the beat signal and reducing the effect of cross beating. Finally, experiments with RADARSAT-1 data are used to illustrate the improved estimation accuracy of the modified algorithm

   
   

   @Article{cummingLi2007:MLBFExtended,
   author = {Cumming, Ian G. and Li, S.},
   journal = {IEEE Transactions on Geoscience and Remote Sensing},
   title = {{Adding Sensitivity to the MLBF Doppler Centroid Estimator}},
   year = {2007},
   issn = {0196-2892},
   month = {Feb.},
   number = {2},
   pages = {279--292},
   volume = {45},
   abstract = {The multilook beat frequency (MLBF) algorithm is the Doppler centroid estimator most commonly used in practice to solve the Doppler ambiguity. However, it still makes errors, notably in medium- or low-contrast scenes. In this paper, we present two ways in which the estimation sensitivity of the MLBF algorithm can be improved. First, we give a more thorough frequency-domain explanation of how the MLBF algorithm works and explain how cross beating and range migration cause estimation difficulties. The first improvement to the algorithm replaces the fast Fourier transform (FFT)-based beat frequency estimator with a more accurate one that uses phase increments. It avoids the FFT limitations of resolution and quantization, especially when the signal is discontinuous in one range cell due to range cell migration or burst mode operation (ScanSAR). A second improvement uses range cell migration correction to straighten the target trajectories before the beat frequency estimator is applied. This has the effect of narrowing the bandwidth of the beat signal and reducing the effect of cross beating. Finally, experiments with RADARSAT-1 data are used to illustrate the improved estimation accuracy of the modified algorithm},
   doi = {10.1109/TGRS.2006.887010},
   keywords = {SAR Processing, Multilook Beat Frequency, MLPF, Doppler Centroid Estimation, Doppler Ambiguity Resolver, DAR, Doppler radar, fast Fourier transforms, frequency estimation, radar signal processing, remote sensing by radar, sensitivity, synthetic aperture radarDoppler ambiguity, Doppler centroid estimator, FFT, Fourier transform, MLBF algorithm, RADARSAT-1, ScanSAR, cross beating, estimation sensitivity, multilook beat frequency algorithm, range migration, target trajectory},
   owner = {ofrey},
   pdf = {../../../docs/cummingLi2007.pdf},
   url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=4069101&isnumber=4069093},
   
   }
   




7. Davide D'Aria and Andrea Monti-Guarnieri. High-Resolution Spaceborne SAR Focusing by SVD-Stolt. IEEE Geoscience and Remote Sensing Letters, 4(4):639-643, October 2007. Keyword(s): Stolt interpolation, geophysical application, high-resolution spaceborne SAR focusing, microwave SAR, motion compensation, orbit curvature, singular value decomposition-Stolt approach, synthetic aperture radar, focusing, geophysical techniques, interpolation, motion compensation, radar resolution, remote sensing by radar, singular value decomposition, spaceborne radar, synthetic aperture radar.

   Abstract:

   In spaceborne synthetic aperture radars (SARs), the orbit curvature may prevent the use of the processor, causing artifacts that depend on both the extent of the orbit arc and the slant range interval. A viable solution has been derived by extending the singular value decomposition-Stolt approach that was proposed for geophysical applications to microwave SAR. The resulting processor has the same simple scheme as the approach but a different (numerical) computation of both the reference and the Stolt interpolation.

   
   

   @Article{DAriaGuarnieri2007,
   author = {D'Aria, Davide and Monti-Guarnieri, Andrea},
   title = {High-Resolution Spaceborne {SAR} Focusing by {SVD}-{S}tolt},
   journal = {IEEE Geoscience and Remote Sensing Letters},
   year = {2007},
   volume = {4},
   number = {4},
   pages = {639-643},
   month = oct,
   issn = {1545-598X},
   abstract = {In spaceborne synthetic aperture radars (SARs), the orbit curvature may prevent the use of the processor, causing artifacts that depend on both the extent of the orbit arc and the slant range interval. A viable solution has been derived by extending the singular value decomposition-Stolt approach that was proposed for geophysical applications to microwave SAR. The resulting processor has the same simple scheme as the approach but a different (numerical) computation of both the reference and the Stolt interpolation.},
   doi = {10.1109/LGRS.2007.903081},
   file = {:DAriaGuarnieri2007.pdf:PDF},
   keywords = {Stolt interpolation;geophysical application;high-resolution spaceborne SAR focusing;microwave SAR;motion compensation;orbit curvature;singular value decomposition-Stolt approach;synthetic aperture radar;focusing;geophysical techniques;interpolation;motion compensation;radar resolution;remote sensing by radar;singular value decomposition;spaceborne radar;synthetic aperture radar},
   owner = {ofrey},
   pdf = {../../../docs/DAriaGuarnieri2007.pdf},
   
   }
   




8. A. Ferretti, G. Savio, R. Barzaghi, A. Borghi, S. Musazzi, F. Novali, C. Prati, and F. Rocca. Submillimeter Accuracy of InSAR Time Series: Experimental Validation. IEEE Trans. Geosci. Remote Sens., 45(5):1142-1153, May 2007. Keyword(s): SAR Processing, Persistent Scatterer Interferometry, PSI, Validation, reflector, deformation, displacement, ground motion, Envisat acquisition, GPS data, InSAR time series, Radarsat acquisition, dihedral reflectors, interferometric synthetic aperture radar, submillimeter accuracy, radar interferometry, remote sensing by radar, synthetic aperture radar, time series.

   Abstract:

   This paper presents the results of a blind experiment that is performed using two pairs of dihedral reflectors. The aim of the experiment was to demonstrate that interferometric synthetic aperture radar (InSAR) measurements can indeed allow a displacement time series estimation with submillimeter accuracy (both in horizontal and vertical directions), provided that the data are properly processed and the impact of in situ as well as atmospheric effects is minimized. One pair of dihedral reflectors was moved a few millimeters between SAR acquisitions, in the vertical and east-west (EW) directions, and the ground truth was compared with the InSAR data. The experiment was designed to allow a multiplatform and multigeometry analysis, i.e., each reflector was carefully pointed in order to be visible in both Envisat and Radarsat acquisitions. Moreover, two pairs of reflectors were used to allow the combination of data gathered along ascending and descending orbits. The standard deviation of the error is 0.75 mm in the vertical direction and 0.58 mm in the horizontal (EW) direction. GPS data were also collected during this experiment in order to cross-check the SAR results

   
   

   @Article{ferrettiSavioBarzaghiBorghiMusazziNovaliPratiRocca2007,
   author = {Ferretti, A. and Savio, G. and Barzaghi, R. and Borghi, A. and Musazzi, S. and Novali, F. and Prati, C. and Rocca, F.},
   journal = {IEEE Trans. Geosci. Remote Sens.},
   title = {Submillimeter Accuracy of {InSAR} Time Series: Experimental Validation},
   year = {2007},
   issn = {0196-2892},
   month = may,
   number = {5},
   pages = {1142-1153},
   volume = {45},
   abstract = {This paper presents the results of a blind experiment that is performed using two pairs of dihedral reflectors. The aim of the experiment was to demonstrate that interferometric synthetic aperture radar (InSAR) measurements can indeed allow a displacement time series estimation with submillimeter accuracy (both in horizontal and vertical directions), provided that the data are properly processed and the impact of in situ as well as atmospheric effects is minimized. One pair of dihedral reflectors was moved a few millimeters between SAR acquisitions, in the vertical and east-west (EW) directions, and the ground truth was compared with the InSAR data. The experiment was designed to allow a multiplatform and multigeometry analysis, i.e., each reflector was carefully pointed in order to be visible in both Envisat and Radarsat acquisitions. Moreover, two pairs of reflectors were used to allow the combination of data gathered along ascending and descending orbits. The standard deviation of the error is 0.75 mm in the vertical direction and 0.58 mm in the horizontal (EW) direction. GPS data were also collected during this experiment in order to cross-check the SAR results},
   doi = {10.1109/TGRS.2007.894440},
   file = {:ferrettiSavioBarzaghiBorghiMusazziNovaliPratiRocca2007.pdf:PDF},
   keywords = {SAR Processing, Persistent Scatterer Interferometry, PSI, Validation, reflector, deformation, displacement, ground motion, Envisat acquisition;GPS data;InSAR time series;Radarsat acquisition;dihedral reflectors;interferometric synthetic aperture radar;submillimeter accuracy;radar interferometry;remote sensing by radar;synthetic aperture radar;time series},
   
   }
   




9. Jeffrey A. Fessler. On NUFFT-based gridding for non-Cartesian MRI. Journal of Magnetic Resonance, 188(2):191-195, 2007. Keyword(s): MRI imaging, NUFFT, Spiral trajectory, Non-Cartesian sampling, Gridding.

   Abstract:

   For MRI with non-Cartesian sampling, the conventional approach to reconstructing images is to use the gridding method with a Kaiser-Bessel (KB) interpolation kernel. Recently, Sha et al. [L. Sha, H. Guo, A.W. Song, An improved gridding method for spiral MRI using nonuniform fast Fourier transform, J. Magn. Reson. 162(2) (2003)] proposed an alternative method based on a nonuniform FFT (NUFFT) with least-squares (LS) design of the interpolation coefficients. They described this LS_NUFFT method as shift variant and reported that it yielded smaller reconstruction approximation errors than the conventional shift-invariant KB approach. This paper analyzes the LS_NUFFT approach in detail. We show that when one accounts for a certain linear phase factor, the core of the LS_NUFFT interpolator is in fact real and shift invariant. Furthermore, we find that the KB approach yields smaller errors than the original LS_NUFFT approach. We show that optimizing certain scaling factors can lead to a somewhat improved LS_NUFFT approach, but the high computation cost seems to outweigh the modest reduction in reconstruction error. We conclude that the standard KB approach, with appropriate parameters as described in the literature, remains the practical method of choice for gridding reconstruction in MRI.

   
   

   @Article{fesslerJMR2007NUFFT,
   author = {Jeffrey A. Fessler},
   journal = {Journal of Magnetic Resonance},
   title = {On {NUFFT}-based gridding for non-{C}artesian {MRI}},
   year = {2007},
   issn = {1090-7807},
   number = {2},
   pages = {191-195},
   volume = {188},
   abstract = {For MRI with non-Cartesian sampling, the conventional approach to reconstructing images is to use the gridding method with a Kaiser-Bessel (KB) interpolation kernel. Recently, Sha et al. [L. Sha, H. Guo, A.W. Song, An improved gridding method for spiral MRI using nonuniform fast Fourier transform, J. Magn. Reson. 162(2) (2003)] proposed an alternative method based on a nonuniform FFT (NUFFT) with least-squares (LS) design of the interpolation coefficients. They described this LS_NUFFT method as shift variant and reported that it yielded smaller reconstruction approximation errors than the conventional shift-invariant KB approach. This paper analyzes the LS_NUFFT approach in detail. We show that when one accounts for a certain linear phase factor, the core of the LS_NUFFT interpolator is in fact real and shift invariant. Furthermore, we find that the KB approach yields smaller errors than the original LS_NUFFT approach. We show that optimizing certain scaling factors can lead to a somewhat improved LS_NUFFT approach, but the high computation cost seems to outweigh the modest reduction in reconstruction error. We conclude that the standard KB approach, with appropriate parameters as described in the literature, remains the practical method of choice for gridding reconstruction in MRI.},
   doi = {http://dx.doi.org/10.1016/j.jmr.2007.06.012},
   keywords = {MRI imaging, NUFFT, Spiral trajectory, Non-Cartesian sampling, Gridding},
   owner = {ofrey},
   url = {http://www.sciencedirect.com/science/article/pii/S1090780707002054},
   
   }
   




10. Andrew Hooper, P Segall, and Howard Zebker. Persistent scatterer interferometric synthetic aperture radar for crustal deformation analysis, with application to Volcán Alcedo, Galápagos. Journal of Geophysical Research: Solid Earth, 112(B7), 2007.
    

    @Article{hooperSegallZebkerJGR2007PSI,
    author = {Hooper, Andrew and Segall, P and Zebker, Howard},
    title = {Persistent scatterer interferometric synthetic aperture radar for crustal deformation analysis, with application to {V}olc{\'a}n {A}lcedo, {G}al{\'a}pagos},
    journal = {Journal of Geophysical Research: Solid Earth},
    year = {2007},
    volume = {112},
    number = {B7},
    owner = {ofrey},
    publisher = {Wiley Online Library},
    
    }
    




11. G. Krieger, A. Moreira, H. Fiedler, I. Hajnsek, M. Werner, M. Younis, and M. Zink. TanDEM-X: A Satellite Formation for High-Resolution SAR Interferometry. IEEE Trans. Geosci. Remote Sens., 45(11):3317-3341, November 2007. Keyword(s): HRTI-3 specification, TanDEM-X mission concept, TerraSAR-X add-on for Digital Elevation Measurement, TerraSAR-X radar satellites, bistatic data acquisition, global digital elevation model, high-resolution SAR interferometry, radar applications, radar imaging techniques, remote sensing applications, satellite formation flying concept, spaceborne radar interferometer, synchonization, synthetic aperture radar, data acquisition, digital elevation models, geophysical techniques, radar imaging, radar interferometry, remote sensing by radar, spaceborne radar, synthetic aperture radar.

    Abstract:

    TerraSAR-X, TanDEM-X ,TanDEM-X (TerraSAR-X add-on for digital elevation measurements) is an innovative spaceborne radar interferometer that is based on two TerraSAR-X radar satellites flying in close formation. The primary objective of the TanDEM-X mission is the generation of a consistent global digital elevation model (DEM) with an unprecedented accuracy, which is equaling or surpassing the HRTI-3 specification. Beyond that, TanDEM-X provides a highly reconfigurable platform for the demonstration of new radar imaging techniques and applications. This paper gives a detailed overview of the TanDEM-X mission concept which is based on the systematic combination of several innovative technologies. The key elements are the bistatic data acquisition employing an innovative phase synchronization link, a novel satellite formation flying concept allowing for the collection of bistatic data with short along-track baselines, as well as the use of new interferometric modes for system verification and DEM calibration. The interferometric performance is analyzed in detail, taking into account the peculiarities of the bistatic operation. Based on this analysis, an optimized DEM data acquisition plan is derived which employs the combination of multiple data takes with different baselines. Finally, a collection of instructive examples illustrates the capabilities of TanDEM-X for the development and demonstration of new remote sensing applications.

    
    

    @Article{kriegerMoreiraFiedlerHajnsekWernerYounisZink2007:TandemXInSAR,
    Title = {{TanDEM-X}: A Satellite Formation for High-Resolution {SAR} Interferometry},
    Author = {Krieger, G. and Moreira, A. and Fiedler, H. and Hajnsek, I. and Werner, M. and Younis, M. and Zink, M.},
    Doi = {10.1109/TGRS.2007.900693},
    ISSN = {0196-2892},
    Month = nov,
    Number = {11},
    Pages = {3317--3341},
    Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4373373},
    Volume = {45},
    Year = {2007},
    Abstract = {TerraSAR-X, TanDEM-X ,TanDEM-X (TerraSAR-X add-on for digital elevation measurements) is an innovative spaceborne radar interferometer that is based on two TerraSAR-X radar satellites flying in close formation. The primary objective of the TanDEM-X mission is the generation of a consistent global digital elevation model (DEM) with an unprecedented accuracy, which is equaling or surpassing the HRTI-3 specification. Beyond that, TanDEM-X provides a highly reconfigurable platform for the demonstration of new radar imaging techniques and applications. This paper gives a detailed overview of the TanDEM-X mission concept which is based on the systematic combination of several innovative technologies. The key elements are the bistatic data acquisition employing an innovative phase synchronization link, a novel satellite formation flying concept allowing for the collection of bistatic data with short along-track baselines, as well as the use of new interferometric modes for system verification and DEM calibration. The interferometric performance is analyzed in detail, taking into account the peculiarities of the bistatic operation. Based on this analysis, an optimized DEM data acquisition plan is derived which employs the combination of multiple data takes with different baselines. Finally, a collection of instructive examples illustrates the capabilities of TanDEM-X for the development and demonstration of new remote sensing applications.},
    Journal = {IEEE Trans. Geosci. Remote Sens.},
    Keywords = {HRTI-3 specification;TanDEM-X mission concept;TerraSAR-X add-on for Digital Elevation Measurement;TerraSAR-X radar satellites;bistatic data acquisition;global digital elevation model;high-resolution SAR interferometry;radar applications;radar imaging techniques;remote sensing applications;satellite formation flying concept;spaceborne radar interferometer;synchonization;synthetic aperture radar;data acquisition;digital elevation models;geophysical techniques;radar imaging;radar interferometry;remote sensing by radar;spaceborne radar;synthetic aperture radar},
    Pdf = {../../../docs/kriegerMoreiraFiedlerHajnsekWernerYounisZink2007.pdf} 
    }
    




12. Riccardo Lanari, Francesco Casu, Mariarosaria Manzo, and Paul Lundgren. Application of the SBAS-DInSAR technique to fault creep: A case study of the Hayward fault, California. Remote Sensing of Environment, 109(1):20-28, 2007.
    

    @Article{lanariCasuManzoLundgrenRSE2007SBASDInSAR,
    author = {Lanari, Riccardo and Casu, Francesco and Manzo, Mariarosaria and Lundgren, Paul},
    title = {Application of the {SBAS}-{DInSAR} technique to fault creep: A case study of the {H}ayward fault, {C}alifornia},
    journal = {Remote Sensing of Environment},
    year = {2007},
    volume = {109},
    number = {1},
    pages = {20--28},
    owner = {ofrey},
    publisher = {Elsevier},
    
    }
    




13. Riccardo Lanari, Francesco Casu, Mariarosaria Manzo, Giovanni Zeni, Paolo Berardino, Michele Manunta, and Antonio Pepe. An Overview of the Small BAseline Subset Algorithm: a DInSAR Technique for Surface Deformation Analysis. Pure and Applied Geophysics, 164(4):637-661, April 2007.

    Abstract:

    We present an overview of the Differential SAR Interferometry algorithm referred to as Small BAseline Subset (SBAS) technique, that allows us to detect surface deformation and to analyze their space-time characteristics. Following the description of the main theoretical aspects of the algorithm, we present several results obtained by applying the SBAS approach in selected case studies relevant to phenomena affecting volcanic areas (Campi Flegrei caldera and Somma-Vesuvio complex, Italy), aquifers (Santa Clara area within the San Francisco bay, California) and landslides (Maratea Valley, Italy). The overall analysis is carried out by using multilook DInSAR interferograms with a spatial resolution of the order of 100 { exttimes} 100 m, computed from SAR data acquired by the ERS-1 and ERS-2 sensors. In particular, we highlight the peculiarities of the SBAS technique and its surface deformation retrieval capability for what concerns both large-scale deformation phenomena and more localized displacement effects.

    
    

    @Article{lanariEtAlPureAppliedGeophysics2007SBASOverviewArticle,
    author = {Lanari, Riccardo and Casu, Francesco and Manzo, Mariarosaria and Zeni, Giovanni and Berardino, Paolo and Manunta, Michele and Pepe, Antonio},
    title = {An Overview of the {Small BAseline Subset} Algorithm: a {DInSAR} Technique for Surface Deformation Analysis},
    journal = {Pure and Applied Geophysics},
    year = {2007},
    volume = {164},
    number = {4},
    pages = {637-661},
    month = apr,
    issn = {1420-9136},
    abstract = {We present an overview of the Differential SAR Interferometry algorithm referred to as Small BAseline Subset (SBAS) technique, that allows us to detect surface deformation and to analyze their space-time characteristics. Following the description of the main theoretical aspects of the algorithm, we present several results obtained by applying the SBAS approach in selected case studies relevant to phenomena affecting volcanic areas (Campi Flegrei caldera and Somma-Vesuvio complex, Italy), aquifers (Santa Clara area within the San Francisco bay, California) and landslides (Maratea Valley, Italy). The overall analysis is carried out by using multilook DInSAR interferograms with a spatial resolution of the order of 100 {	exttimes} 100 m, computed from SAR data acquired by the ERS-1 and ERS-2 sensors. In particular, we highlight the peculiarities of the SBAS technique and its surface deformation retrieval capability for what concerns both large-scale deformation phenomena and more localized displacement effects.},
    day = {01},
    doi = {10.1007/s00024-007-0192-9},
    file = {:lanariEtAlPureAppliedGeophysics2007SBASOverviewArticle.pdf:PDF},
    owner = {ofrey},
    url = {https://doi.org/10.1007/s00024-007-0192-9},
    
    }
    




14. R. Linnehan, D. Brady, J. Schindler, L. Perlovsky, and M. Rangaswamy. On the design of SAR apertures using the Cramer-Rao bound. Aerospace and Electronic Systems, IEEE Transactions on, 43(1):344 -355, january 2007. Keyword(s): Cramer-Rao bound, SAR, likelihood function, scatterer parameter vector, synthetic aperture radar, military radar, synthetic aperture radar;.

    Abstract:

    The Cramer-Rao inequality is applied to the likelihood function of the synthetic aperture radar (SAR) scatterer parameter vector to relate the choice of flight path to estimation performance. Estimation error bounds for the scatterer parameter vector (including height) are developed for multi-dimensional synthetic apertures, and quantify the performance enhancement over a limited sector of the image plane relative to standard-aperture single-pass SAR missions. An efficient means for the design and analysis of SAR waveforms and flight paths is proposed using simulated scattering models that are limited in size. Comparison of the error bounds to those for standard-aperture SAR show that estimates of scatterer range and cross-range positions are accurate for multi-dimensional aperture SAR, even with the additional estimator for height. Furthermore, multi-dimensional SAR is shown to address the layover problem

    
    

    @Article{4194776,
    author = {Linnehan, R. and Brady, D. and Schindler, J. and Perlovsky, L. and Rangaswamy, M.},
    journal = {Aerospace and Electronic Systems, IEEE Transactions on},
    title = {On the design of SAR apertures using the Cramer-Rao bound},
    year = {2007},
    issn = {0018-9251},
    month = {january},
    number = {1},
    pages = {344 -355},
    volume = {43},
    abstract = {The Cramer-Rao inequality is applied to the likelihood function of the synthetic aperture radar (SAR) scatterer parameter vector to relate the choice of flight path to estimation performance. Estimation error bounds for the scatterer parameter vector (including height) are developed for multi-dimensional synthetic apertures, and quantify the performance enhancement over a limited sector of the image plane relative to standard-aperture single-pass SAR missions. An efficient means for the design and analysis of SAR waveforms and flight paths is proposed using simulated scattering models that are limited in size. Comparison of the error bounds to those for standard-aperture SAR show that estimates of scatterer range and cross-range positions are accurate for multi-dimensional aperture SAR, even with the additional estimator for height. Furthermore, multi-dimensional SAR is shown to address the layover problem},
    doi = {10.1109/TAES.2007.357138},
    keywords = {Cramer-Rao bound;SAR;likelihood function;scatterer parameter vector;synthetic aperture radar;military radar;synthetic aperture radar;},
    
    }
    




15. R. M. C. Lopes, K. L. Mitchell, E. R. Stofan, J. I. Lunine, R. Lorenz, F. Paganelli, R. L. Kirk, C. A. Wood, S. D. Wall, L. E. Robshaw, A. D. Fortes, C. D. Neish, J. Radebaugh, E. Reffet, S. J. Ostro, Charles Elachi, M. D. Allison, Y. Anderson, R. Boehmer, G. Boubin, P. Callahan, P. Encrenaz, E. Flamini, G. Francescetti, Y. Gim, G. Hamilton, Scott Hensley, M. A. Janssen, W. T. K. Johnson, K. Kelleher, D.O. Muhleman, G. Ori, R. Orosei, G. Picardi, F. Posa, L.E. Roth, R. Seu, S. Shaffer, L.A. Soderblom, B. Stiles, S. Vetrella, R.D. West, L. Wye, and Howard A. Zebker. Cryovolcanic features on Titan's surface as revealed by the Cassini Titan Radar Mapper. Icarus, 186(2):395-412, 2007. Keyword(s): Cassini, Cassini Radar, Titan, Volcanism, Satellites of Saturn.

    Abstract:

    The Cassini Titan Radar Mapper obtained Synthetic Aperture Radar images of Titan's surface during four fly-bys during the mission's first year. These images show that Titan's surface is very complex geologically, showing evidence of major planetary geologic processes, including cryovolcanism. This paper discusses the variety of cryovolcanic features identified from SAR images, their possible origin, and their geologic context. The features which we identify as cryovolcanic in origin include a large (180 km diameter) volcanic construct (dome or shield), several extensive flows, and three calderas which appear to be the source of flows. The composition of the cryomagma on Titan is still unknown, but constraints on rheological properties can be estimated using flow thickness. Rheological properties of one flow were estimated and appear inconsistent with ammonia-water slurries, and possibly more consistent with ammonia-water-methanol slurries. The extent of cryovolcanism on Titan is still not known, as only a small fraction of the surface has been imaged at sufficient resolution. Energetic considerations suggest that cryovolcanism may have been a dominant process in the resurfacing of Titan.

    
    

    @Article{lopesEtAlIcarus2007CassiniRadarTitanMapper,
    author = {R. M. C. Lopes and K. L. Mitchell and E. R. Stofan and J. I. Lunine and R. Lorenz and F. Paganelli and R. L. Kirk and C. A. Wood and S. D. Wall and L. E. Robshaw and A. D. Fortes and C. D. Neish and J. Radebaugh and E. Reffet and S. J. Ostro and Charles Elachi and M. D. Allison and Y. Anderson and R. Boehmer and G. Boubin and P. Callahan and P. Encrenaz and E. Flamini and G. Francescetti and Y. Gim and G. Hamilton and Scott Hensley and M. A. Janssen and W. T. K. Johnson and K. Kelleher and D.O. Muhleman and G. Ori and R. Orosei and G. Picardi and F. Posa and L.E. Roth and R. Seu and S. Shaffer and L.A. Soderblom and B. Stiles and S. Vetrella and R.D. West and L. Wye and Howard A. Zebker},
    journal = {Icarus},
    title = {Cryovolcanic features on Titan's surface as revealed by the Cassini Titan Radar Mapper},
    year = {2007},
    issn = {0019-1035},
    number = {2},
    pages = {395-412},
    volume = {186},
    abstract = {The Cassini Titan Radar Mapper obtained Synthetic Aperture Radar images of Titan's surface during four fly-bys during the mission's first year. These images show that Titan's surface is very complex geologically, showing evidence of major planetary geologic processes, including cryovolcanism. This paper discusses the variety of cryovolcanic features identified from SAR images, their possible origin, and their geologic context. The features which we identify as cryovolcanic in origin include a large (180 km diameter) volcanic construct (dome or shield), several extensive flows, and three calderas which appear to be the source of flows. The composition of the cryomagma on Titan is still unknown, but constraints on rheological properties can be estimated using flow thickness. Rheological properties of one flow were estimated and appear inconsistent with ammonia-water slurries, and possibly more consistent with ammonia-water-methanol slurries. The extent of cryovolcanism on Titan is still not known, as only a small fraction of the surface has been imaged at sufficient resolution. Energetic considerations suggest that cryovolcanism may have been a dominant process in the resurfacing of Titan.},
    doi = {http://dx.doi.org/10.1016/j.icarus.2006.09.006},
    file = {:lopesEtAlIcarus2007CassiniRadarTitanMapper.pdf:PDF},
    keywords = {Cassini, Cassini Radar, Titan, Volcanism, Satellites of Saturn},
    owner = {ofrey},
    pdf = {../../../docs/lopesEtAlIcarus2007CassiniRadarTitanMapper.pdf},
    url = {http://www.sciencedirect.com/science/article/pii/S0019103506003198},
    
    }
    




16. Alexander Löw and Wolfram Mauser. Generation of geometrically and radiometrically terrain corrected SAR image products. Remote Sensing of Environment, 106(3):337-349, February 2007. Keyword(s): SAR Processing, Radiometric Calibration, Calibration, Image enhancement, Image processing, Synthetic aperture radar, Terrain mapping, SAR geocoding, Radiometric normalization.

    Abstract:

    Terrain undulations affect the geometric and radiometric quality of synthetic aperture radar images. The correction of these effects becomes indispensable when quantitative image analysis is performed with respect to the derivation of geo- and biophysical parameters. The paper presents a rigorous approach for geometric and radiometric correction of SAR images. Using a digital elevation model, the imaging geometry is reconstructed and is used to perform geometric and radiometric correction of terrain induced distortions. The importance of a stringent radiometric correction based on the integration of the image brightness is emphasized. The approach guarantees that the energy contained in the image data is preserved throughout the geocoding process. The resulting backscattering images are fully terrain corrected and can be used for further quantitative investigations and may also improve qualitative studies as e.g. land cover classifications. The technique is applicable for different sensor types and image products, including already geocoded SAR images. The effect of different resolutions of digital elevation models used for the correction of the backscattering coefficient is investigated.

    
    

    @Article{LoewMauser2007:GeoRadiometricCorr,
    Title = {{Generation of geometrically and radiometrically terrain corrected SAR image products}},
    Author = {L{\"o}w, Alexander and Mauser, Wolfram},
    Month = {feb},
    Number = {3},
    Pages = {337--349},
    Url = {http://www.sciencedirect.com/science/article/B6V6V-4M57H9F-1/2/f58e22796d6ead0c64253c63e0c5f48f},
    Volume = {106},
    Year = {2007},
    Abstract = {Terrain undulations affect the geometric and radiometric quality of synthetic aperture radar images. The correction of these effects becomes indispensable when quantitative image analysis is performed with respect to the derivation of geo- and biophysical parameters. The paper presents a rigorous approach for geometric and radiometric correction of SAR images. Using a digital elevation model, the imaging geometry is reconstructed and is used to perform geometric and radiometric correction of terrain induced distortions. The importance of a stringent radiometric correction based on the integration of the image brightness is emphasized. The approach guarantees that the energy contained in the image data is preserved throughout the geocoding process. The resulting backscattering images are fully terrain corrected and can be used for further quantitative investigations and may also improve qualitative studies as e.g. land cover classifications. The technique is applicable for different sensor types and image products, including already geocoded SAR images. The effect of different resolutions of digital elevation models used for the correction of the backscattering coefficient is investigated.},
    Journal = {Remote Sensing of Environment},
    Keywords = {SAR Processing, Radiometric Calibration, Calibration, Image enhancement, Image processing, Synthetic aperture radar, Terrain mapping, SAR geocoding, Radiometric normalization},
    Owner = {ofrey},
    Pdf = {../../../docs/loewMauser2007.pdf} 
    }
    




17. Jean-Michel Martinez and Thuy Le Toan. Mapping of flood dynamics and spatial distribution of vegetation in the Amazon floodplain using multitemporal SAR data. Remote Sensing of Environment, 108(3):209 - 223, 2007. Keyword(s): Wetland, Floodplain, Vegetation, Flood, Temporal dynamic, Radar, Classification.

    Abstract:

    This paper presents the use of time series of SAR images to map the flood temporal dynamics and the spatial distribution of vegetation over a large Amazonian floodplain. The region under study (3500 km2) presents a diversity of landscape units with open lakes, bogs, large meadows, savannahs, alluvial forests and terra firma forest, covered by 21 images acquired by J-ERS between 1993 and 1997. Ground data include in situ observations of vegetation structure and flood extent as well as water level records. Image analysis demonstrates that temporal variations of the radar backscatter can be used to monitor efficiently the flood extent regardless of the landscape units. Also, analysis of the backscatter temporal variation greatly reduces the confusion between smooth surfaces (e.g. open water bodies, bare soils) inherent to L-band backscatter. The mapping method is based on decision rules over two decision variables: 1) the mean backscatter coefficient computed over the whole time series; 2) the total change computed using an Absolute Change estimator. The first variable provides classification into rough vegetation types while the second variable yields a direct estimate of the intensity of change that is related to flood dynamics. The classifier is first applied to the whole time series to map the maximum and minimum flood extent by defining 3 flood conditions: never flooded (NF); occasionally flooded (OF); permanently flooded (PF). It also furnishes the broad land cover type: open water/bare soils/low vegetation/forest. The accuracy of the flood extent mapping shows a kappa value of 0.82. Then, the classifier is run iteratively on the OF pixels to monitor flood stages during which the occasionally flooded areas get submerged. The mapping accuracy is assessed on one intermediate flood stage, showing a precision in excess of 90%. The importance of the time sampling for flood mapping is discussed along with the influence of SAR backscatter accuracy and the number of images. Then general guidelines for floodplain mapping are presented. By combining water level reports with maps of different flood stages the flooding pattern can be retrieved along with the vegetation succession processes. It is shown that the spatial distribution of vegetation communities is governed by flood stress and can be modelled as a function of the mean annual exposure to floods.

    
    

    @Article{martinezLeToanRSE2007FloodMappingUsingMultitemporalSARData,
    author = {Jean-Michel Martinez and Thuy Le Toan},
    title = {Mapping of flood dynamics and spatial distribution of vegetation in the Amazon floodplain using multitemporal {SAR} data},
    journal = {Remote Sensing of Environment},
    year = {2007},
    volume = {108},
    number = {3},
    pages = {209 - 223},
    issn = {0034-4257},
    abstract = {This paper presents the use of time series of SAR images to map the flood temporal dynamics and the spatial distribution of vegetation over a large Amazonian floodplain. The region under study (3500 km2) presents a diversity of landscape units with open lakes, bogs, large meadows, savannahs, alluvial forests and terra firma forest, covered by 21 images acquired by J-ERS between 1993 and 1997. Ground data include in situ observations of vegetation structure and flood extent as well as water level records. Image analysis demonstrates that temporal variations of the radar backscatter can be used to monitor efficiently the flood extent regardless of the landscape units. Also, analysis of the backscatter temporal variation greatly reduces the confusion between smooth surfaces (e.g. open water bodies, bare soils) inherent to L-band backscatter. The mapping method is based on decision rules over two decision variables: 1) the mean backscatter coefficient computed over the whole time series; 2) the total change computed using an Absolute Change estimator. The first variable provides classification into rough vegetation types while the second variable yields a direct estimate of the intensity of change that is related to flood dynamics. The classifier is first applied to the whole time series to map the maximum and minimum flood extent by defining 3 flood conditions: never flooded (NF); occasionally flooded (OF); permanently flooded (PF). It also furnishes the broad land cover type: open water/bare soils/low vegetation/forest. The accuracy of the flood extent mapping shows a kappa value of 0.82. Then, the classifier is run iteratively on the OF pixels to monitor flood stages during which the occasionally flooded areas get submerged. The mapping accuracy is assessed on one intermediate flood stage, showing a precision in excess of 90%. The importance of the time sampling for flood mapping is discussed along with the influence of SAR backscatter accuracy and the number of images. Then general guidelines for floodplain mapping are presented. By combining water level reports with maps of different flood stages the flooding pattern can be retrieved along with the vegetation succession processes. It is shown that the spatial distribution of vegetation communities is governed by flood stress and can be modelled as a function of the mean annual exposure to floods.},
    doi = {https://doi.org/10.1016/j.rse.2006.11.012},
    keywords = {Wetland, Floodplain, Vegetation, Flood, Temporal dynamic, Radar, Classification},
    owner = {ofrey},
    url = {http://www.sciencedirect.com/science/article/pii/S0034425706004585},
    
    }
    




18. Adriano Meta, Peter Hoogeboom, and L. P. Ligthart. Signal Processing for FMCW SAR. IEEE Transactions on Geoscience and Remote Sensing, 45(11):3519-3532, November 2007. Keyword(s): SAR Processing, SAR Focusing, Azimuth Focusing, FMCW, FMCW SAR, geophysical signal processing, geophysical techniques, image sensors, radar imaging, synthetic aperture radar, Delft University of Technology, FMCW technique, Netherlands, SAR technique, conventional stop-and-go approximation, data collection, frequency-modulated continuous-wave technology, high resolution image sensor, pulse-radar algorithms, signal model, signal processing, signal transmission, synthetic aperture radar, Frequency, High-resolution imaging, Image resolution, Image sensors, Limiting, Radar signal processing, Signal processing, Signal processing algorithms, Signal resolution, Synthetic aperture radar, Doppler frequency correction, frequency-modulated continuous wave (FMCW), nonlinearity correction, synthetic aperture radar (SAR).

    Abstract:

    The combination of frequency-modulated continuous-wave (FMCW) technology and synthetic aperture radar (SAR) techniques leads to lightweight cost-effective imaging sensors of high resolution. One limiting factor to the use of FMCW sensors is the well-known presence of nonlinearities in the transmitted signal. This results in contrast- and range-resolution degradation, particularly when the system is intended for high-resolution long-range applications, as it is the case for SAR. This paper presents a novel processing solution, which solves the nonlinearity problem for the whole range profile. Additionally, the conventional stop-and-go approximation used in pulse-radar algorithms is not valid in FMCW SAR applications under certain circumstances. Therefore, the motion within the sweep needs to be taken into account. Analytical development of the FMCW SAR signal model, starting from the deramped signal and without using the stop-and-go approximation, is presented in this paper. The model is then applied to stripmap, spotlight, and single-transmitter/multiple-receiver digital-beamforming SAR operational mode. The proposed algorithms are verified by processing real FMCW SAR data collected with the demonstrator system built at the Delft University of Technology.

    
    

    @Article{metaHoogeboomLigthartTGRS2007FMCWSARFocusing,
    author = {Adriano Meta and Peter Hoogeboom and L. P. Ligthart},
    title = {Signal Processing for {FMCW} {SAR}},
    journal = {IEEE Transactions on Geoscience and Remote Sensing},
    year = {2007},
    volume = {45},
    number = {11},
    month = nov,
    pages = {3519-3532},
    issn = {0196-2892},
    doi = {10.1109/TGRS.2007.906140},
    abstract = {The combination of frequency-modulated continuous-wave (FMCW) technology and synthetic aperture radar (SAR) techniques leads to lightweight cost-effective imaging sensors of high resolution. One limiting factor to the use of FMCW sensors is the well-known presence of nonlinearities in the transmitted signal. This results in contrast- and range-resolution degradation, particularly when the system is intended for high-resolution long-range applications, as it is the case for SAR. This paper presents a novel processing solution, which solves the nonlinearity problem for the whole range profile. Additionally, the conventional stop-and-go approximation used in pulse-radar algorithms is not valid in FMCW SAR applications under certain circumstances. Therefore, the motion within the sweep needs to be taken into account. Analytical development of the FMCW SAR signal model, starting from the deramped signal and without using the stop-and-go approximation, is presented in this paper. The model is then applied to stripmap, spotlight, and single-transmitter/multiple-receiver digital-beamforming SAR operational mode. The proposed algorithms are verified by processing real FMCW SAR data collected with the demonstrator system built at the Delft University of Technology.},
    keywords = {SAR Processing, SAR Focusing, Azimuth Focusing, FMCW, FMCW SAR, geophysical signal processing;geophysical techniques;image sensors;radar imaging;synthetic aperture radar;Delft University of Technology;FMCW technique;Netherlands;SAR technique;conventional stop-and-go approximation;data collection;frequency-modulated continuous-wave technology;high resolution image sensor;pulse-radar algorithms;signal model;signal processing;signal transmission;synthetic aperture radar;Frequency;High-resolution imaging;Image resolution;Image sensors;Limiting;Radar signal processing;Signal processing;Signal processing algorithms;Signal resolution;Synthetic aperture radar;Doppler frequency correction;frequency-modulated continuous wave (FMCW);nonlinearity correction;synthetic aperture radar (SAR)},
    owner = {ofrey},
    
    }
    




19. Andrea Monti-Guarnieri and Stefano Tebaldini. Hybrid Cramer-Rao Bounds for Crustal Displacement Field Estimators in SAR Interferometry. IEEE Signal Processing Letters, 14(12):1012-1015, December 2007. Keyword(s): SAR Processing, APS variance, SAR interferometry, atmospheric phase screen, crustal displacement field estimator, deterministic parameter, error analysis, hybrid Cramer-Rao bounds, line-of-sight crustal deformation, radar signal analysis, spaceborne synthetic aperture radar interferometry, stochastic variable, system configuration, target decorrelation, decorrelation, error analysis, interferometry, radar signal processing, radar tracking, spaceborne radar, stochastic processes, synthetic aperture radar;.

    Abstract:

    This letter focuses on the performance achievable by spaceborne synthetic aperture radar interferometry (InSAR) in the estimation of line-of-sight crustal deformations from acquisitions over a distributed scatterer. Our model is suited for exploiting the hybrid Cramer-Rao bound (HCRB), where the unknowns are both deterministic parameters and stochastic variables. We take into account both target decorrelation and atmospheric phase screen (APS). This approach leads to a viable evaluation of InSAR performance as a function of system configuration, target decorrelation, and APS variance.

    
    

    @Article{montiGuarnieriTebaldini2007,
    author = {Monti-Guarnieri, Andrea and Tebaldini, Stefano},
    journal = {IEEE Signal Processing Letters},
    title = {Hybrid Cramer-Rao Bounds for Crustal Displacement Field Estimators in SAR Interferometry},
    year = {2007},
    issn = {1070-9908},
    month = dec,
    number = {12},
    pages = {1012-1015},
    volume = {14},
    abstract = {This letter focuses on the performance achievable by spaceborne synthetic aperture radar interferometry (InSAR) in the estimation of line-of-sight crustal deformations from acquisitions over a distributed scatterer. Our model is suited for exploiting the hybrid Cramer-Rao bound (HCRB), where the unknowns are both deterministic parameters and stochastic variables. We take into account both target decorrelation and atmospheric phase screen (APS). This approach leads to a viable evaluation of InSAR performance as a function of system configuration, target decorrelation, and APS variance.},
    doi = {10.1109/LSP.2007.904705},
    file = {:montiGuarnieriTebaldini2007.pdf:PDF},
    keywords = {SAR Processing, APS variance;SAR interferometry;atmospheric phase screen;crustal displacement field estimator;deterministic parameter;error analysis;hybrid Cramer-Rao bounds;line-of-sight crustal deformation;radar signal analysis;spaceborne synthetic aperture radar interferometry;stochastic variable;system configuration;target decorrelation;decorrelation;error analysis;interferometry;radar signal processing;radar tracking;spaceborne radar;stochastic processes;synthetic aperture radar;},
    
    }
    




20. Robert. L. Morrison, Minh N. Do, and David C. Munson. SAR Image Autofocus By Sharpness Optimization: A Theoretical Study. IEEE Transactions on Image Processing, 16(9):2309-2321, September 2007. Keyword(s): SAR Processing, Autofocus, SAR image autofocus, intensity-squared metric, point-targets image, sharpness optimization, synthetic aperture radar, image processing, optimisation, synthetic aperture radar, Algorithms, Artificial Intelligence, Computer Simulation, Image Enhancement, Image Interpretation, Computer-Assisted, Models, Theoretical, Pattern Recognition, Automated, Reproducibility of Results, Sensitivity and Specificity;.

    Abstract:

    Synthetic aperture radar (SAR) autofocus techniques that optimize sharpness metrics can produce excellent restorations in comparison with conventional autofocus approaches. To help formalize the understanding of metric-based SAR autofocus methods, and to gain more insight into their performance, we present a theoretical analysis of these techniques using simple image models. Specifically, we consider the intensity-squared metric, and a dominant point-targets image model, and derive expressions for the resulting objective function. We examine the conditions under which the perfectly focused image models correspond to stationary points of the objective function. A key contribution is that we demonstrate formally, for the specific case of intensity-squared minimization autofocus, the mechanism by which metric-based methods utilize the multichannel defocusing model of SAR autofocus to enforce the stationary point property for multiple image columns. Furthermore, our analysis shows that the objective function has a special separble property through which it can be well approximated locally by a sum of 1-D functions of each phase error component. This allows fast performance through solving a sequence of 1-D optimization problems for each phase component simultaneously. Simulation results using the proposed models and actual SAR imagery confirm that the analysis extends well to realistic situations.

    
    

    @Article{morrisonDoMunsonTIP2007SARAutofocusSharpnessOptimization,
    author = {Morrison, Robert. L. and Do, Minh N. and Munson, David C.},
    journal = {IEEE Transactions on Image Processing},
    title = {{SAR} Image Autofocus By Sharpness Optimization: A Theoretical Study},
    year = {2007},
    issn = {1057-7149},
    month = sep,
    number = {9},
    pages = {2309-2321},
    volume = {16},
    abstract = {Synthetic aperture radar (SAR) autofocus techniques that optimize sharpness metrics can produce excellent restorations in comparison with conventional autofocus approaches. To help formalize the understanding of metric-based SAR autofocus methods, and to gain more insight into their performance, we present a theoretical analysis of these techniques using simple image models. Specifically, we consider the intensity-squared metric, and a dominant point-targets image model, and derive expressions for the resulting objective function. We examine the conditions under which the perfectly focused image models correspond to stationary points of the objective function. A key contribution is that we demonstrate formally, for the specific case of intensity-squared minimization autofocus, the mechanism by which metric-based methods utilize the multichannel defocusing model of SAR autofocus to enforce the stationary point property for multiple image columns. Furthermore, our analysis shows that the objective function has a special separble property through which it can be well approximated locally by a sum of 1-D functions of each phase error component. This allows fast performance through solving a sequence of 1-D optimization problems for each phase component simultaneously. Simulation results using the proposed models and actual SAR imagery confirm that the analysis extends well to realistic situations.},
    doi = {10.1109/TIP.2007.903252},
    file = {:morrisonDoMunsonAutofocus2007.pdf:PDF},
    keywords = {SAR Processing, Autofocus, SAR image autofocus;intensity-squared metric;point-targets image;sharpness optimization;synthetic aperture radar;image processing;optimisation;synthetic aperture radar;Algorithms;Artificial Intelligence;Computer Simulation;Image Enhancement;Image Interpretation, Computer-Assisted;Models, Theoretical;Pattern Recognition, Automated;Reproducibility of Results;Sensitivity and Specificity;},
    pdf = {../../../docs/morrisonDoMunsonAutofocus2007.pdf},
    
    }
    




21. Ross F. Nelson, Peter Hyde, Patrick Johnson, Bomono Emessiene, Marc L. Imhoff, Robert Campbell, and Wilson Edwards. Investigating RaDAR-LiDAR synergy in a North Carolina pine forest. Remote Sensing of Environment, 110(1):98-108, September 2007. Keyword(s): SAR Processing, Biomass, Forest, VHFRaDAR, profiling LiDAR, biomass, RaDAR-LiDAR synergy, VHFSAR DATA, SMALL-FOOTPRINT LIDAR, AIRBORNE LASER DATA, STEM VOLUME, STAND CHARACTERISTICS, AERIAL-PHOTOGRAPHY, VEGETATION BIOMASS, CONIFEROUS FOREST, BOREAL FORESTS, SCANNER DATA.

    Abstract:

    A low frequency (80-120 MHz) VHF RaDAR, BioSAR, specifically designed for forest biomass estimation and a profiling LiDAR, PALS, were flown over loblolly pine plantations in the southeastern United States. LiDAR-only, RaDAR-only, and joint LiDAR-RaDAR linear models were developed to determine if returns from two sensors could be used to estimate pine biomass more accurately and precisely than returns from either sensor alone. The best five-variable RaDAR model explained 81.8\% (R (2)) of the stem green biomass variability, with a regression RMSE of 57.5 t/ha. The best one-variable LiDAR model explained 93.3\% of the biomass variation (RMSE=33.9 t/ha). Combining the RaDAR normalized volumetric returns with the profiling LiDAR ranging measurements did little to improve the best LiDAR-only model. The best LiDAR-RaDAR model explained 93.8\% of the biomass variation (RSME=32.7 t/ha). Cross-validation and training/test validation procedures demonstrated (1) that all models are unbiased and (2) the increased precision of the LiDAR-only and LiDAR-RaDAR models. The results of this investigation and a companion study indicate that there is little to be gained combining VHF-RaDAR volumetric returns and profiling LiDAR ranging measurements in pine forests; a LiDAR ranging system is sufficient for accurate, precise biomass estimation.

    
    

    @Article{nelsonHydeJohnsonEmessieneImhoffCampbellEdwards2007:RaDARLiDARSynergy,
    Title = {Investigating {RaDAR-LiDAR} synergy in a {North Carolina} pine forest},
    Author = {Nelson, Ross F. and Hyde, Peter and Johnson, Patrick and Emessiene, Bomono and Imhoff, Marc L. and Campbell, Robert and Edwards, Wilson},
    Doi = {{10.1016/j.rse.2007.02.006}},
    ISSN = {{0034-4257}},
    Month = {sep},
    Number = {1},
    Pages = {98-108},
    Url = {http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6V6V-4NF2HJT-1-1&_cdi=5824&_user=5294990&_orig=search&_coverDate=09%2F14%2F2007&_sk=998899998&view=c&wchp=dGLzVtb-zSkWA&md5=c6e6d79abfd854eb19f8ebc9f402a25a&ie=/sdarticle.pdf},
    Volume = {110},
    Year = {2007},
    Abstract = {A low frequency (80-120 MHz) VHF RaDAR, BioSAR, specifically designed for forest biomass estimation and a profiling LiDAR, PALS, were flown over loblolly pine plantations in the southeastern United States. LiDAR-only, RaDAR-only, and joint LiDAR-RaDAR linear models were developed to determine if returns from two sensors could be used to estimate pine biomass more accurately and precisely than returns from either sensor alone. The best five-variable RaDAR model explained 81.8\% (R (2)) of the stem green biomass variability, with a regression RMSE of 57.5 t/ha. The best one-variable LiDAR model explained 93.3\% of the biomass variation (RMSE=33.9 t/ha). Combining the RaDAR normalized volumetric returns with the profiling LiDAR ranging measurements did little to improve the best LiDAR-only model. The best LiDAR-RaDAR model explained 93.8\% of the biomass variation (RSME=32.7 t/ha). Cross-validation and training/test validation procedures demonstrated (1) that all models are unbiased and (2) the increased precision of the LiDAR-only and LiDAR-RaDAR models. The results of this investigation and a companion study indicate that there is little to be gained combining VHF-RaDAR volumetric returns and profiling LiDAR ranging measurements in pine forests; a LiDAR ranging system is sufficient for accurate, precise biomass estimation.},
    Journal = {Remote Sensing of Environment},
    Keywords = {SAR Processing, Biomass, Forest, VHFRaDAR, profiling LiDAR, biomass, RaDAR-LiDAR synergy, VHFSAR DATA, SMALL-FOOTPRINT LIDAR, AIRBORNE LASER DATA, STEM VOLUME, STAND CHARACTERISTICS, AERIAL-PHOTOGRAPHY, VEGETATION BIOMASS, CONIFEROUS FOREST, BOREAL FORESTS, SCANNER DATA},
    Owner = {ofrey},
    Pdf = {../../../docs/nelsonHydeJohnsonEmessieneImhoffCampbellEdwards2007.pdf} 
    }
    




22. Jean-Marie Nicolas, Gabriel Vasile, Michel Gay, Florence Tupin, and Emmanuel Trouvé. SAR processing in the temporal domain: application to direct interferogram generation and mountain glacier monitoring. Canadian Journal of Remote Sensing, 33(1):52-59, 2007. Keyword(s): SAR Processing, Time-Domain Back-Projection, InSAR, Interferometry, SAR Interferometry, Glacier Displacement Measurement, ERS, Spaceborne SAR.

    Abstract:

    Synthetic aperture radar (SAR) interferometry has the potential to measure temperate glacier displacement with a large coverage of the surface compared with pointwise terrestrial ground measurements. The significant topographic relief in mountainous areas, however, where most alpine glaciers are located, makes the use of SAR imagery rather difficult. Among the difficulties, when the resolution increases, the focusing of satellite SAR images, usually performed in the frequency domain with a constant-height hypothesis, becomes a critical issue. SAR processing in the temporal domain is a different approach that enables the use of information such as the local topography. In this paper, we present an original method to perform this temporal domain focusing by modeling the relative motion of the satellite and Earth points. The method allows production of SAR single look complex (SLC) images directly in ground geometry and reduces the need for resampling and phase correction to obtain interferograms. A tandem pair of European remote sensing (ERS) SAR images acquired over the Mont-Blanc area is used to illustrate the proposed approach. The results are presented with amplitude images and interferograms measuring glacier 1 day displacements and are compared with the results from the differential interferometric automated process applied to survey of nature (DIAPASON) and repeated orbit interferometry package (ROI-PAC) conventional SAR processors.

    
    

    @Article{NicolasVasileGayTupinTrouve2007:TDBPInSAR,
    Title = {{SAR processing in the temporal domain: application to direct interferogram generation and mountain glacier monitoring}},
    Author = {Jean-Marie Nicolas and Gabriel Vasile and Michel Gay and Florence Tupin and Emmanuel Trouv{\'e}},
    Number = {1},
    Pages = {52--59},
    Url = {http://pubs.nrc-cnrc.gc.ca/cjrs/m07-005.html},
    Volume = {33},
    Year = {2007},
    Abstract = {Synthetic aperture radar (SAR) interferometry has the potential to measure temperate glacier displacement with a large coverage of the surface compared with pointwise terrestrial ground measurements. The significant topographic relief in mountainous areas, however, where most alpine glaciers are located, makes the use of SAR imagery rather difficult. Among the difficulties, when the resolution increases, the focusing of satellite SAR images, usually performed in the frequency domain with a constant-height hypothesis, becomes a critical issue. SAR processing in the temporal domain is a different approach that enables the use of information such as the local topography. In this paper, we present an original method to perform this temporal domain focusing by modeling the relative motion of the satellite and Earth points. The method allows production of SAR single look complex (SLC) images directly in ground geometry and reduces the need for resampling and phase correction to obtain interferograms. A tandem pair of European remote sensing (ERS) SAR images acquired over the Mont-Blanc area is used to illustrate the proposed approach. The results are presented with amplitude images and interferograms measuring glacier 1 day displacements and are compared with the results from the differential interferometric automated process applied to survey of nature (DIAPASON) and repeated orbit interferometry package (ROI-PAC) conventional SAR processors.},
    Journal = {Canadian Journal of Remote Sensing},
    Keywords = {SAR Processing, Time-Domain Back-Projection, InSAR, Interferometry, SAR Interferometry, Glacier Displacement Measurement, ERS, Spaceborne SAR},
    Owner = {ofrey},
    Pdf = {../../../docs/NicolasVasileGayTupinTrouve2007.pdf} 
    }
    




23. D. Pastina, F. Colone, and P. Lombardo. Effect of Apodization on SAR Image Understanding. IEEE Transactions on Geoscience and Remote Sensing, 45(11):3533-3551, November 2007. Keyword(s): SAR Processing, Apodization, Spatially Variant Apodization, SVA, SAR images, apodization effect, homogeneous regions, main lobe resolution preservation, pixel complex amplitude, probability density function, radar cross sections, sidelobe level reduction, statistical moments, statistical properties, supervised classification, synthetic aperture radar images, geophysical techniques, image classification, radar cross-sections, synthetic aperture radar.

    Abstract:

    This paper investigates the effect of apodization on the statistical properties of synthetic aperture radar (SAR) images and its impact on the capability of extracting information from homogeneous regions of apodized SAR images. The statistical model for the pixel complex amplitude of the apodized image is derived in terms of both probability density function and statistical moments. Knowledge of the statistical properties is then used to develop appropriate schemes for parameter estimation and supervised classification of homogeneous regions with different radar cross sections in apodized SAR images. The performance analysis shows that the new techniques (properly derived for the apodized case) provide information extraction capabilities only slightly worse than those provided by the conventional techniques applied to the nonapodized case. This allows us to conclude that the use of nonlinear apodization yields sidelobe level reduction and main lobe resolution preservation that can be traded with the small losses above. A full characterization of the estimation and classification performance of these new techniques shows that nonlinear apodization globally introduces a performance degradation comparable to a reduction of the number of looks of a factor of 1.455 for a homogeneous region.

    
    

    @Article{pastinaColoneLombardo2007:Apodization,
    author = {Pastina, D. and Colone, F. and Lombardo, P.},
    journal = {IEEE Transactions on Geoscience and Remote Sensing},
    title = {Effect of Apodization on {SAR} Image Understanding},
    year = {2007},
    issn = {0196-2892},
    month = nov,
    number = {11},
    pages = {3533-3551},
    volume = {45},
    abstract = {This paper investigates the effect of apodization on the statistical properties of synthetic aperture radar (SAR) images and its impact on the capability of extracting information from homogeneous regions of apodized SAR images. The statistical model for the pixel complex amplitude of the apodized image is derived in terms of both probability density function and statistical moments. Knowledge of the statistical properties is then used to develop appropriate schemes for parameter estimation and supervised classification of homogeneous regions with different radar cross sections in apodized SAR images. The performance analysis shows that the new techniques (properly derived for the apodized case) provide information extraction capabilities only slightly worse than those provided by the conventional techniques applied to the nonapodized case. This allows us to conclude that the use of nonlinear apodization yields sidelobe level reduction and main lobe resolution preservation that can be traded with the small losses above. A full characterization of the estimation and classification performance of these new techniques shows that nonlinear apodization globally introduces a performance degradation comparable to a reduction of the number of looks of a factor of 1.455 for a homogeneous region.},
    doi = {10.1109/TGRS.2007.905309},
    keywords = {SAR Processing, Apodization, Spatially Variant Apodization, SVA, SAR images, apodization effect, homogeneous regions, main lobe resolution preservation, pixel complex amplitude, probability density function, radar cross sections, sidelobe level reduction, statistical moments, statistical properties, supervised classification, synthetic aperture radar images, geophysical techniques, image classification, radar cross-sections, synthetic aperture radar},
    
    }
    




24. D. Perissin and A. Ferretti. Urban-Target Recognition by Means of Repeated Spaceborne SAR Images. IEEE Trans. Geosci. Remote Sens., 45(12):4043 -4058, December 2007. Keyword(s): SAR Processing, Doppler radar, Image recognition, Image resolution, Image sensors, Polarization, Radar imaging, Radar scattering, Spaceborne radar, Synthetic aperture radar, Target recognition, airborne radar, geophysical signal processing, geophysical techniques, object recognition, radar interferometry, radar polarimetry, synthetic aperture radar, Doppler centroid acquisition geometry, automatic scattering structure recognition, elevated backscatterers, extended resonating targets, ground level backscatterers, normal baseline acquisition geometry, radar signal amplitude, radar signal polarization diversity, repeated spaceborne SAR images, resonating dihedrals, resonating poles, resonating trihedrals, simple dihedrals, simple poles, simple trihedrals, spaceborne C band SAR, synthetic aperture radar, urban target recognition, Interferometry, polarimetry, radar target recognition, synthetic aperture radar (SAR), urban areas;.

    Abstract:

    The relative low resolution (~25 m times 5 m on the ground) of spaceborne C-band synthetic aperture radar (SAR) data as acquired, for example, by European Space Agency sensors ERS and Envisat, can be significantly increased (up to submeter precisions) by processing coherently long series of images. Moreover, by analyzing the amplitude of the radar signal and by exploiting polarization diversity, the main radar characteristics of urban targets can be estimated, and a system for automatic recognition of a set of scattering structures can be developed. In this paper, we study the variation of the amplitude of the received radar signal as a function of the acquisition geometry [normal baseline and Doppler centroid (DC)] to retrieve the extension of the targets in range and azimuth. The dependence of the radar amplitude on temperature at the time of acquisition has been discovered to be very useful to identify extended resonating targets. Dihedrals are discriminated from specular or trihedral reflectors through the phase of Envisat alternating polarization (AP) acquisitions. By means of all gathered radar measurements, the bases for the development of a system for the automatic recognition of six main typologies of urban SAR targets (ground-level and elevated backscatterers, simple and resonating dihedrals, poles and trihedrals) have been laid. Radar data are then combined with in situ surveys and aerial photos, allowing a first assessment of the methodology in urban area.

    
    

    @Article{perissinFerrettiTGRS2007,
    author = {Perissin, D. and Ferretti, A.},
    title = {Urban-Target Recognition by Means of Repeated Spaceborne {SAR} Images},
    journal = {IEEE Trans. Geosci. Remote Sens.},
    year = {2007},
    volume = {45},
    number = {12},
    pages = {4043 -4058},
    month = dec,
    issn = {0196-2892},
    abstract = {The relative low resolution (~25 m times 5 m on the ground) of spaceborne C-band synthetic aperture radar (SAR) data as acquired, for example, by European Space Agency sensors ERS and Envisat, can be significantly increased (up to submeter precisions) by processing coherently long series of images. Moreover, by analyzing the amplitude of the radar signal and by exploiting polarization diversity, the main radar characteristics of urban targets can be estimated, and a system for automatic recognition of a set of scattering structures can be developed. In this paper, we study the variation of the amplitude of the received radar signal as a function of the acquisition geometry [normal baseline and Doppler centroid (DC)] to retrieve the extension of the targets in range and azimuth. The dependence of the radar amplitude on temperature at the time of acquisition has been discovered to be very useful to identify extended resonating targets. Dihedrals are discriminated from specular or trihedral reflectors through the phase of Envisat alternating polarization (AP) acquisitions. By means of all gathered radar measurements, the bases for the development of a system for the automatic recognition of six main typologies of urban SAR targets (ground-level and elevated backscatterers, simple and resonating dihedrals, poles and trihedrals) have been laid. Radar data are then combined with in situ surveys and aerial photos, allowing a first assessment of the methodology in urban area.},
    doi = {10.1109/TGRS.2007.906092},
    file = {:perissinFerrettiTGRS2007.pdf:PDF},
    keywords = {SAR Processing, Doppler radar;Image recognition;Image resolution;Image sensors;Polarization;Radar imaging;Radar scattering;Spaceborne radar;Synthetic aperture radar;Target recognition;airborne radar;geophysical signal processing;geophysical techniques;object recognition;radar interferometry;radar polarimetry;synthetic aperture radar;Doppler centroid acquisition geometry;automatic scattering structure recognition;elevated backscatterers;extended resonating targets;ground level backscatterers;normal baseline acquisition geometry;radar signal amplitude;radar signal polarization diversity;repeated spaceborne SAR images;resonating dihedrals;resonating poles;resonating trihedrals;simple dihedrals;simple poles;simple trihedrals;spaceborne C band SAR;synthetic aperture radar;urban target recognition;Interferometry;polarimetry;radar target recognition;synthetic aperture radar (SAR);urban areas;},
    pdf = {../../../docs/perissinFerrettiTGRS2007.pdf},
    
    }
    




25. P. Prats, Karlus A. Câmara de Macedo, A. Reigber, R. Scheiber, and J. J. Mallorqui. Comparison of Topography- and Aperture-Dependent Motion Compensation Algorithms for Airborne SAR. IEEE Geosci. Remote Sens. Lett., 4(3):349-353, 2007. Keyword(s): SAR Processing, Motion Compensation, PTA-Algorithm, Precise Topography- and Aperture-Dependent (PTA) Algorithm, SATA, Subaperture Topography- and Aperture-dependent (SATA) Algorithm, Frequency Division (FD) Algorithm, Topography-Based Motion Compensation, ESAR, L-Band Calibration, image registration, interferometry, motion compensation (MoCo), synthetic aperture radar (SAR), Comparison, Comparsion of Motion Compensation Algorithms, InSAR, Airborne SAR.

    Abstract:

    This letter presents a comparison between three Fourier-based motion compensation (MoCo) algorithms for airborne synthetic aperture radar (SAR) systems. These algorithms circumvent the limitations of conventional MoCo, namely the assumption of a reference height and the beam-center approximation. All these approaches rely on the inherent time-frequency relation in SAR systems but exploit it differently, with the consequent differences in accuracy and computational burden. After a brief overview of the three approaches, the performance of each algorithm is analyzed with respect to azimuthal topography accommodation, angle accommodation, and maximum frequency of track deviations with which the algorithm can cope. Also, an analysis on the computational complexity is presented. Quantitative results are shown using real data acquired by the Experimental SAR system of the German Aerospace Center (DLR).

    
    

    @Article{PratsMacedoReigberScheiberMallorqui2007:MoComp,
    author = {Prats, P. and C{\^a}mara de Macedo, Karlus A. and Reigber, A. and Scheiber, R. and Mallorqui, J. J.},
    journal = {IEEE Geosci. Remote Sens. Lett.},
    title = {Comparison of Topography- and Aperture-Dependent Motion Compensation Algorithms for Airborne {SAR}},
    year = {2007},
    issn = {1545-598X},
    number = {3},
    pages = {349--353},
    volume = {4},
    abstract = {This letter presents a comparison between three Fourier-based motion compensation (MoCo) algorithms for airborne synthetic aperture radar (SAR) systems. These algorithms circumvent the limitations of conventional MoCo, namely the assumption of a reference height and the beam-center approximation. All these approaches rely on the inherent time-frequency relation in SAR systems but exploit it differently, with the consequent differences in accuracy and computational burden. After a brief overview of the three approaches, the performance of each algorithm is analyzed with respect to azimuthal topography accommodation, angle accommodation, and maximum frequency of track deviations with which the algorithm can cope. Also, an analysis on the computational complexity is presented. Quantitative results are shown using real data acquired by the Experimental SAR system of the German Aerospace Center (DLR).},
    booktitle = {IEEE Geosci. Remote Sens. Lett.},
    keywords = {SAR Processing, Motion Compensation, PTA-Algorithm, Precise Topography- and Aperture-Dependent (PTA) Algorithm, SATA, Subaperture Topography- and Aperture-dependent (SATA) Algorithm, Frequency Division (FD) Algorithm, Topography-Based Motion Compensation, ESAR, L-Band Calibration, image registration, interferometry, motion compensation (MoCo), synthetic aperture radar (SAR), Comparison, Comparsion of Motion Compensation Algorithms, InSAR, Airborne SAR},
    owner = {ofrey},
    pdf = {../../../docs/PratsMacedoReigberScheiberMallorqui2007.pdf},
    url = {http://ieeexplore.ieee.org/iel5/8859/4271437/04271465.pdf},
    
    }
    




26. Fabio Rocca. Modeling Interferogram Stacks. IEEE Trans. Geosci. Remote Sens., 45(10):3289-3299, October 2007. Keyword(s): SAR Processing, PSI, Persistent Scatterer Interferometry, Differential SAR Interferometry, D-InSAR, InSAR, SAR Interferometry, Interferometry, Decorrelation, Temporal Decorrelation, C-band measurement, DInSAR, ERS-1 data, Italy, Rome, agricultural areas, differential interferometric SAR, distributed targets, geometrical decorrelation, interferogram stack modeling, permanent scatterers, progressive ground motion, progressively decorrelating targets, sinusoidal ground motion, synthetic aperture radar interferometry, temporal decorrelation, radiowave interferometry, remote sensing by radar, synthetic aperture radar, vegetation mapping;.

    Abstract:

    Synthetic aperture radar interferometry is limited by temporal and geometrical decorrelation. Permanent scatterers (PSs) are helpful to overcome these problems, but their density in agricultural and out-of-town areas is not always sufficient. The forthcoming availability of satellite platforms with thinner orbital tubes and shorter revisit times will enhance the use of interferogram stacks, which are usable for distributed and progressively decorrelating targets, like those found in agricultural areas. To estimate the possibilities of the interferogram stack technique, a Markovian model for the temporal decorrelation is considered. ERS-1 data measured in C-band over Rome with a three-day repeat cycle are used to identify the parameters for this model, namely, the decorrelation time (estimated as 40 days) and the short-term coherence (estimated as 0.6). In the hypothesis of small deviations from a model of the motion, the optimal weights to be used to combine a sequence of interferograms taken at intervals that are shorter than the decorrelation time are calculated in the cases of progressive and sinusoidal ground motion. The dispersion of the optimal estimate of the motion is then determined. This model is extended to frequencies other than C-band. These evaluations are compared with the known results obtained for PSs. As an example, the case of a time interval between the takes of T = 12 days is considered. With N consecutive images, interferogram stack results are equivalent to PSs if the pixel count in the window used to smooth the interferograms grows with N2.

    
    

    @Article{rocca2007TGRS_PSI,
    author = {Rocca, Fabio},
    title = {Modeling Interferogram Stacks},
    journal = {IEEE Trans. Geosci. Remote Sens.},
    year = {2007},
    volume = {45},
    number = {10},
    pages = {3289-3299},
    month = oct,
    issn = {0196-2892},
    abstract = {Synthetic aperture radar interferometry is limited by temporal and geometrical decorrelation. Permanent scatterers (PSs) are helpful to overcome these problems, but their density in agricultural and out-of-town areas is not always sufficient. The forthcoming availability of satellite platforms with thinner orbital tubes and shorter revisit times will enhance the use of interferogram stacks, which are usable for distributed and progressively decorrelating targets, like those found in agricultural areas. To estimate the possibilities of the interferogram stack technique, a Markovian model for the temporal decorrelation is considered. ERS-1 data measured in C-band over Rome with a three-day repeat cycle are used to identify the parameters for this model, namely, the decorrelation time (estimated as 40 days) and the short-term coherence (estimated as 0.6). In the hypothesis of small deviations from a model of the motion, the optimal weights to be used to combine a sequence of interferograms taken at intervals that are shorter than the decorrelation time are calculated in the cases of progressive and sinusoidal ground motion. The dispersion of the optimal estimate of the motion is then determined. This model is extended to frequencies other than C-band. These evaluations are compared with the known results obtained for PSs. As an example, the case of a time interval between the takes of T = 12 days is considered. With N consecutive images, interferogram stack results are equivalent to PSs if the pixel count in the window used to smooth the interferograms grows with N2.},
    doi = {10.1109/TGRS.2007.902286},
    file = {:rocca2007TGRS_PSI.pdf:PDF},
    keywords = {SAR Processing, PSI, Persistent Scatterer Interferometry, Differential SAR Interferometry, D-InSAR, InSAR, SAR Interferometry, Interferometry, Decorrelation, Temporal Decorrelation, C-band measurement;DInSAR;ERS-1 data;Italy;Rome;agricultural areas;differential interferometric SAR;distributed targets;geometrical decorrelation;interferogram stack modeling;permanent scatterers;progressive ground motion;progressively decorrelating targets;sinusoidal ground motion;synthetic aperture radar interferometry;temporal decorrelation;radiowave interferometry;remote sensing by radar;synthetic aperture radar;vegetation mapping;},
    owner = {ofrey},
    pdf = {../../../docs/rocca2007TGRS_PSI.pdf},
    
    }
    




27. T. O. Saebo, Roy E. Hansen, and A. Hanssen. Relative Height Estimation by Cross-Correlating Ground-Range Synthetic Aperture Sonar Images. IEEE Journal of Oceanic Engineering, 32(4):971-982, October 2007. Keyword(s): Synthetic Aperture Sonar, SAS, oceanographic techniques, seafloor phenomena, sonar imaging, synthetic aperture sonar, Elba Island, InSAS-2000 experiment, Italy, SAS processing, along-track resolution, azimuth resolution, broadband signals, coherent frequency-dependent scattering, correction technique, cross correlations, geometrical decorrelation effect, image acquisition, mathematical model, moving platform, seafloor relative height, signal-to-noise ratio, sonar images beamforming, synthetic aperture sonar imaging, time-delay estimates, vertically displaced receivers, Azimuth, Coherence, Decorrelation, Frequency estimation, Mathematical model, Scattering, Sea floor, Signal resolution, Signal to noise ratio, Synthetic aperture sonar, Bathymetry, coherence, cross correlation, height estimation, interferometry, synthetic aperture sonar (SAS), time-delay estimation.

    Abstract:

    The relative height of the seafloor can be estimated by using two vertically displaced receivers. In this paper, we propose techniques to improve the accuracy of the estimated height. Our results are based on the use of synthetic aperture sonar (SAS) imaging, which implies coherent addition of complex images acquired from a moving platform. The SAS processing improves the along-track (or azimuth) resolution, as well as the signal-to-noise ratio (SNR), which in turn improves the estimated height accuracy. We show that the shift of the effective center frequency induced by coherent, frequency-dependent scattering affect the time-delay estimates from complex cross correlations, and we propose a correction technique for broadband signals with uneven magnitude spectra. To reduce the effect of geometrical decorrelation and increase the coherence between the images, we beamform the sonar images onto an a priori estimate of the seafloor height before correlating. We develop a mathematical model for the imaging geometry. Finally, we demonstrate our proposed estimators by providing relative seafloor height estimates from real aperture and SAS images, obtained during the InSAS-2000 experiment at Elba Island in Italy. In particular, we demonstrate that the SAS image quality is significantly improved by inclusion of the height estimates as a priori information.

    
    

    @Article{saeboHansenHanssenJOE2007RelativeHeightEstimationCrossCorrelatingGroundRangeSASonar,
    author = {T. O. Saebo and Hansen, Roy E. and A. Hanssen},
    journal = {IEEE Journal of Oceanic Engineering},
    title = {Relative Height Estimation by Cross-Correlating Ground-Range Synthetic Aperture Sonar Images},
    year = {2007},
    issn = {0364-9059},
    month = {Oct},
    number = {4},
    pages = {971-982},
    volume = {32},
    abstract = {The relative height of the seafloor can be estimated by using two vertically displaced receivers. In this paper, we propose techniques to improve the accuracy of the estimated height. Our results are based on the use of synthetic aperture sonar (SAS) imaging, which implies coherent addition of complex images acquired from a moving platform. The SAS processing improves the along-track (or azimuth) resolution, as well as the signal-to-noise ratio (SNR), which in turn improves the estimated height accuracy. We show that the shift of the effective center frequency induced by coherent, frequency-dependent scattering affect the time-delay estimates from complex cross correlations, and we propose a correction technique for broadband signals with uneven magnitude spectra. To reduce the effect of geometrical decorrelation and increase the coherence between the images, we beamform the sonar images onto an a priori estimate of the seafloor height before correlating. We develop a mathematical model for the imaging geometry. Finally, we demonstrate our proposed estimators by providing relative seafloor height estimates from real aperture and SAS images, obtained during the InSAS-2000 experiment at Elba Island in Italy. In particular, we demonstrate that the SAS image quality is significantly improved by inclusion of the height estimates as a priori information.},
    doi = {10.1109/JOE.2007.895244},
    file = {:saeboHansenHanssenJOE2007RelativeHeightEstimationCrossCorrelatingGroundRangeSASonar.pdf:PDF},
    keywords = {Synthetic Aperture Sonar, SAS, oceanographic techniques;seafloor phenomena;sonar imaging;synthetic aperture sonar;Elba Island;InSAS-2000 experiment;Italy;SAS processing;along-track resolution;azimuth resolution;broadband signals;coherent frequency-dependent scattering;correction technique;cross correlations;geometrical decorrelation effect;image acquisition;mathematical model;moving platform;seafloor relative height;signal-to-noise ratio;sonar images beamforming;synthetic aperture sonar imaging;time-delay estimates;vertically displaced receivers;Azimuth;Coherence;Decorrelation;Frequency estimation;Mathematical model;Scattering;Sea floor;Signal resolution;Signal to noise ratio;Synthetic aperture sonar;Bathymetry;coherence;cross correlation;height estimation;interferometry;synthetic aperture sonar (SAS);time-delay estimation},
    
    }
    




28. T. J. Schulz. Optimal Sharpness Function for SAR Autofocus. IEEE Signal Processing Letters, 14(1):27-30, January 2007. Keyword(s): error correction, error statistics, maximum likelihood estimation, radar imaging, synthetic aperture radar, image-domain sharpness function, autofocusing, phase-error correction, synthetic aperture radar imagery, SAR, optimization, statistical estimation, maximum-likelihood estimation, maximum-posterior estimation, intensity-squared sharpness, Layout, Phase estimation, Optimization methods, Synthetic aperture radar, Discrete Fourier transforms, Maximum likelihood estimation, Reflectivity, Error correction, Computer errors, Signal processing, MAP estimation, synthetic aperture radar (SAR).

    Abstract:

    Phase-error correction through the optimization of an image-domain sharpness function provides one method for the auto-focus of synthetic aperture radar (SAR) imagery. Several ad-hoc sharpness functions have been proposed, implemented, and analyzed, but none of these has been motivated as the solution to a well-defined statistical estimation problem. In this letter, a SAR sharpness function is derived that induces the solution to maximum-likelihood and maximum-posterior estimation for idealized SAR data. Furthermore, a limiting form of the optimal sharpness function is shown to be the popular intensity-squared sharpness

    
    

    @Article{schulzIEEESPL2007OptimalSharpnessFuntionSARAutofocus,
    author = {T. J. {Schulz}},
    journal = {IEEE Signal Processing Letters},
    title = {Optimal Sharpness Function for {SAR} Autofocus},
    year = {2007},
    issn = {1558-2361},
    month = jan,
    number = {1},
    pages = {27-30},
    volume = {14},
    abstract = {Phase-error correction through the optimization of an image-domain sharpness function provides one method for the auto-focus of synthetic aperture radar (SAR) imagery. Several ad-hoc sharpness functions have been proposed, implemented, and analyzed, but none of these has been motivated as the solution to a well-defined statistical estimation problem. In this letter, a SAR sharpness function is derived that induces the solution to maximum-likelihood and maximum-posterior estimation for idealized SAR data. Furthermore, a limiting form of the optimal sharpness function is shown to be the popular intensity-squared sharpness},
    doi = {10.1109/LSP.2006.881525},
    file = {:schulzIEEESPL2007OptimalSharpnessFuntionSARAutofocus.pdf:PDF},
    keywords = {error correction;error statistics;maximum likelihood estimation;radar imaging;synthetic aperture radar;image-domain sharpness function;autofocusing;phase-error correction;synthetic aperture radar imagery;SAR;optimization;statistical estimation;maximum-likelihood estimation;maximum-posterior estimation;intensity-squared sharpness;Layout;Phase estimation;Optimization methods;Synthetic aperture radar;Discrete Fourier transforms;Maximum likelihood estimation;Reflectivity;Error correction;Computer errors;Signal processing;MAP estimation;synthetic aperture radar (SAR)},
    owner = {ofrey},
    
    }
    




29. T. Sparr, Roy E. Hansen, H. J. Callow, and J. Groen. Enhancing target shadows in SAR images. Electronics Letters, 43(5):69-70, March 2007. Keyword(s): SAR Processing, image enhancement, radar imaging, synthetic aperture radar, SAR images, fixed focus shadow enhancement, radar image, sharp target image, synthetic aperture radar, target shadow enhancement.

    Abstract:

    A method called fixed focus shadow enhancement is proposed. The purpose is to sharpen target shadows in synthetic aperture radar images. The method applies a fixed focus range to a given target, resulting in a sharp target image and a sharp target shadow. Other parts of the radar image, including the background against which the shadow is seen, are smeared

    
    

    @Article{sparrHansenCallowGroenElectrLett2007EnhancingTargetShadowsInSARImages,
    author = {T. Sparr and Roy E. Hansen and H. J. Callow and J. Groen},
    title = {Enhancing target shadows in {SAR} images},
    journal = {Electronics Letters},
    year = {2007},
    volume = {43},
    number = {5},
    pages = {69-70},
    month = mar,
    issn = {0013-5194},
    abstract = {A method called fixed focus shadow enhancement is proposed. The purpose is to sharpen target shadows in synthetic aperture radar images. The method applies a fixed focus range to a given target, resulting in a sharp target image and a sharp target shadow. Other parts of the radar image, including the background against which the shadow is seen, are smeared},
    doi = {10.1049/el:20073883},
    file = {:sparrHansenCallowGroenElectrLett2007EnhancingTargetShadowsInSARImages.pdf:PDF},
    keywords = {SAR Processing, image enhancement;radar imaging;synthetic aperture radar;SAR images;fixed focus shadow enhancement;radar image;sharp target image;synthetic aperture radar;target shadow enhancement},
    
    }
    




30. Z. Su, Y. Peng, and X. Wang. Feature-Independent Aperture Evaluator for the Curvilinear SAR. IEEE Geosci. Remote Sens. Lett., 4(2):191-195, 2007. Keyword(s): SAR Processing, Non-Linear Flight Path, SAR Tomography, 3D Feature Extraction, Feature Extraction, Curvilinear SAR.

    Abstract:

    Curvilinear synthetic aperture radar (SAR), as a more practicable 3-D SAR imaging system, utilizes parametric target feature estimates extracted from the received data to reconstruct the target image. The reconstructed image quality is then impacted by the estimation accuracy of the features. In this letter, through discussing the correlation between the system parameters and the estimation performance of the curvilinear SAR, a conclusion can be drawn on how the overall location accuracy of a target is determined by the correlation between the azimuth and elevation coordinates of the flight path, compactly characterizing the curvilinear aperture. Consequently, a new index, determined only with the aperture parameters, is proposed as an aperture evaluator, which is referred to as the feature-independent aperture evaluator (FAE). FAE can be used for guiding the operational aperture design.

    
    

    @Article{suPengWang2007:NonLinearSARTOMO,
    Title = {{Feature-Independent Aperture Evaluator for the Curvilinear SAR}},
    Author = {Su, Z. and Peng, Y. and Wang, X.},
    Number = {2},
    Pages = {191--195},
    Url = {http://ieeexplore.ieee.org/iel5/8859/4156144/04156172.pdf},
    Volume = {4},
    Year = {2007},
    Abstract = {Curvilinear synthetic aperture radar (SAR), as a more practicable 3-D SAR imaging system, utilizes parametric target feature estimates extracted from the received data to reconstruct the target image. The reconstructed image quality is then impacted by the estimation accuracy of the features. In this letter, through discussing the correlation between the system parameters and the estimation performance of the curvilinear SAR, a conclusion can be drawn on how the overall location accuracy of a target is determined by the correlation between the azimuth and elevation coordinates of the flight path, compactly characterizing the curvilinear aperture. Consequently, a new index, determined only with the aperture parameters, is proposed as an aperture evaluator, which is referred to as the feature-independent aperture evaluator (FAE). FAE can be used for guiding the operational aperture design.},
    Journal = {IEEE Geosci. Remote Sens. Lett.},
    Keywords = {SAR Processing, Non-Linear Flight Path, SAR Tomography, 3D Feature Extraction, Feature Extraction, Curvilinear SAR},
    Pdf = {../../../docs/suPengWang2007.pdf} 
    }
    




31. Ridha Touzi. Target Scattering Decomposition in Terms of Roll-Invariant Target Parameters. IEEE Trans. Geosci. Remote Sens., 45(1):73-84, January 2007. Keyword(s): SAR Processing, Polarimetric Decomposition, Canada, Cloude-Pottier incoherent target decomposition, Cloude-Pottier scattering type, Kennaugh-Huynen scattering matrix condiagonalization, Ontario, Pauli basis, Ramsar Mer Bleue wetland site, asymmetric scattering, coherent target scattering, entropy, maximum polarization parameters, polarimetric Convair-580 airborne SAR, polarization basis invariant representation, roll invariant target parameters, scattering vector model, symmetric scattering magnitude, symmetric scattering phase, synthetic aperture radar, target orientation angle, target phase parameters, target scattering decomposition, S-matrix theory, airborne radar, geophysical techniques, radar theory, remote sensing by radar, synthetic aperture radar.

    Abstract:

    The Kennaugh-Huynen scattering matrix con-diagonalization is projected into the Pauli basis to derive a new scattering vector model for the representation of coherent target scattering. This model permits a polarization basis invariant representation of coherent target scattering in terms of five independent target parameters, the magnitude and phase of the symmetric scattering type introduced in this paper, and the maximum polarization parameters (orientation, helicity, and maximum return). The new scattering vector model served for the assessment of the Cloude-Pottier incoherent target decomposition. Whereas the Cloude-Pottier scattering type alpha and entropy H are roll invariant, beta and the so-called target-phase parameters do depend on the target orientation angle for asymmetric scattering. The scattering vector model is then used as the basis for the development of new coherent and incoherent target decompositions in terms of unique and roll-invariant target parameters. It is shown that both the phase and magnitude of the symmetric scattering type should be used for an unambiguous description of symmetric target scattering. Target helicity is required for the assessment of the symmetry-asymmetry nature of target scattering. The symmetric scattering type phase is shown to be very promising for wetland classification in particular, using polarimetric Convair-580 synthetic aperture radar data collected over the Ramsar Mer Bleue wetland site to the east of Ottawa, Ontario, Canada

    
    

    @Article{Touzi2007:PolDecomp,
    Title = {Target Scattering Decomposition in Terms of Roll-Invariant Target Parameters},
    Author = {Touzi, Ridha},
    Doi = {10.1109/TGRS.2006.886176},
    ISSN = {0196-2892},
    Month = jan,
    Number = {1},
    Pages = {73-84},
    Volume = {45},
    Year = {2007},
    Abstract = {The Kennaugh-Huynen scattering matrix con-diagonalization is projected into the Pauli basis to derive a new scattering vector model for the representation of coherent target scattering. This model permits a polarization basis invariant representation of coherent target scattering in terms of five independent target parameters, the magnitude and phase of the symmetric scattering type introduced in this paper, and the maximum polarization parameters (orientation, helicity, and maximum return). The new scattering vector model served for the assessment of the Cloude-Pottier incoherent target decomposition. Whereas the Cloude-Pottier scattering type alpha and entropy H are roll invariant, beta and the so-called target-phase parameters do depend on the target orientation angle for asymmetric scattering. The scattering vector model is then used as the basis for the development of new coherent and incoherent target decompositions in terms of unique and roll-invariant target parameters. It is shown that both the phase and magnitude of the symmetric scattering type should be used for an unambiguous description of symmetric target scattering. Target helicity is required for the assessment of the symmetry-asymmetry nature of target scattering. The symmetric scattering type phase is shown to be very promising for wetland classification in particular, using polarimetric Convair-580 synthetic aperture radar data collected over the Ramsar Mer Bleue wetland site to the east of Ottawa, Ontario, Canada},
    Journal = {IEEE Trans. Geosci. Remote Sens.},
    Keywords = {SAR Processing, Polarimetric Decomposition, Canada;Cloude-Pottier incoherent target decomposition;Cloude-Pottier scattering type;Kennaugh-Huynen scattering matrix condiagonalization;Ontario;Pauli basis;Ramsar Mer Bleue wetland site;asymmetric scattering;coherent target scattering;entropy;maximum polarization parameters;polarimetric Convair-580 airborne SAR;polarization basis invariant representation;roll invariant target parameters;scattering vector model;symmetric scattering magnitude;symmetric scattering phase;synthetic aperture radar;target orientation angle;target phase parameters;target scattering decomposition;S-matrix theory;airborne radar;geophysical techniques;radar theory;remote sensing by radar;synthetic aperture radar},
    Pdf = {../../../docs/touzi2007.pdf} 
    }
    




32. Marijke Vandewal, Rainer Speck, and Helmut Süss. Efficient and Precise Processing for Squinted Spotlight SAR through a Modified Stolt Mapping. EURASIP Journal on Advances in Signal Processing, 2007:1-7, 2007.

    Abstract:

    Processing of squinted SAR spotlight data is a challenge because of the significant range migration effects of the raw data over the coherent aperture time. Although in theory the (omega, k)-algorithm takes care of these aspects, its digital implementation requires a time-consuming interpolation step. Moreover, the limited precision of this interpolation can introduce distortions at the edges of the final image especially for squinted geometries. A wave number domain processing using a modified Stolt mapping will be developed and analyzed to enhance the quality of the final SAR image. Additionally, the proposed algorithm has a decreased computational load compared to the original (omega,k)-algorithm. Simulation results will validate the focusing and efficiency performances of the modified wave number domain algorithm.

    
    

    @Article{vandewalSpeckSuessModifiedStoltMapping2007,
    author = {Marijke Vandewal and Rainer Speck and Helmut S\"uss},
    title = {Efficient and Precise Processing for Squinted Spotlight {SAR} through a Modified {Stolt} Mapping},
    journal = {EURASIP Journal on Advances in Signal Processing},
    year = {2007},
    volume = {2007},
    pages = {1-7},
    abstract = {Processing of squinted SAR spotlight data is a challenge because of the significant range migration effects of the raw data over the coherent aperture time. Although in theory the (omega, k)-algorithm takes care of these aspects, its digital implementation requires a time-consuming interpolation step. Moreover, the limited precision of this interpolation can introduce distortions at the edges of the final image especially for squinted geometries. A wave number domain processing using a modified Stolt mapping will be developed and analyzed to enhance the quality of the final SAR image. Additionally, the proposed algorithm has a decreased computational load compared to the original (omega,k)-algorithm. Simulation results will validate the focusing and efficiency performances of the modified wave number domain algorithm.},
    doi = {10.1155/2007/59704},
    file = {:vandewalSpeckSuessModifiedStoltMapping2007.pdf:PDF},
    issue = {ID 59704},
    pdf = {../../../docs/vandewalSpeckSuessModifiedStoltMapping2007.pdf},
    url = {http://downloads.hindawi.com/journals/asp/2007/059704.pdf},
    
    }
    




33. J-P Wigneron, Yann Kerr, Philippe Waldteufel, Kauzar Saleh, M-J Escorihuela, Philippe Richaume, Paolo Ferrazzoli, Patricia De Rosnay, Robert Gurney, J-C Calvet, and others. L-band microwave emission of the biosphere (L-MEB) model: Description and calibration against experimental data sets over crop fields. Remote Sensing of Environment, 107(4):639-655, 2007.
    

    @Article{Wigneron2007,
    author = {Wigneron, J-P and Kerr, Yann and Waldteufel, Philippe and Saleh, Kauzar and Escorihuela, M-J and Richaume, Philippe and Ferrazzoli, Paolo and De Rosnay, Patricia and Gurney, Robert and Calvet, J-C and others},
    title = {L-band microwave emission of the biosphere (L-MEB) model: Description and calibration against experimental data sets over crop fields},
    journal = {Remote Sensing of Environment},
    year = {2007},
    volume = {107},
    number = {4},
    pages = {639--655},
    owner = {ofrey},
    publisher = {Elsevier},
    
    }
    

Conference articles

1. A. Ahlander, H. Hellsten, K. Lind, J. Lindgren, and B. Svensson. Architectural Challenges in Memory-Intensive, Real-Time Image Forming. In Int. Conf. on Parallel Processing, pages 35-35, Sept. 2007. Keyword(s): SAR Processing, Back-Projection, Time-Domain Back-Projection, Fast-Factorized Back-Projection, FFBP, GBP, interpolation, parallel algorithms, parallel architectures, radar imaging, real-time systems, storage management, synthetic aperture radarcomplex memory access pattern, computer architecture, flight path error compensation, memory-intensive real-time image forming, parallel algorithm, performance-intensive data interpolation, synthetic aperture radar system.

   Abstract:

   The real-time image forming in future, high-end synthetic aperture radar systems is an example of an application that puts new demands on computer architectures. The initial question is whether it is at all possible to meet the demands with state-of-the-art technology or foreseeable new technology. It is therefore crucial to understand the computational flow, with its associated memory, bandwidth and processing demands. In this paper we analyse the application in order to, primarily, understand the algorithms and identify the challenges they present on a basic architectural level. The processing in the radar system is characterized by working on huge data sets, having complex memory access patterns, and doing real-time compensations for flight path errors. We propose algorithm solutions and execution schemes in interplay with a two-level (coarse-grain/fine-grain) system parallelization approach, and we provide approximate models on which the demands are quantified. In particular, we consider the choice of method for the performance- intensive data interpolations. This choice presents a trade-off problem between computational performance and size of working memory. The results of this study will serve as a basis for further, more detailed architecture studies.

   
   

   @InProceedings{ahlanderHellstenLindLindgrenSvensson2007:TDBPRealTime,
   Title = {Architectural Challenges in Memory-Intensive, Real-Time Image Forming},
   Author = {Ahlander, A. and Hellsten, H. and Lind, K. and Lindgren, J. and Svensson, B.},
   Booktitle = {Int. Conf. on Parallel Processing},
   Doi = {10.1109/ICPP.2007.18},
   Month = {Sept.},
   Pages = {35-35},
   Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4343842&isnumber=4343799},
   Year = {2007},
   Abstract = {The real-time image forming in future, high-end synthetic aperture radar systems is an example of an application that puts new demands on computer architectures. The initial question is whether it is at all possible to meet the demands with state-of-the-art technology or foreseeable new technology. It is therefore crucial to understand the computational flow, with its associated memory, bandwidth and processing demands. In this paper we analyse the application in order to, primarily, understand the algorithms and identify the challenges they present on a basic architectural level. The processing in the radar system is characterized by working on huge data sets, having complex memory access patterns, and doing real-time compensations for flight path errors. We propose algorithm solutions and execution schemes in interplay with a two-level (coarse-grain/fine-grain) system parallelization approach, and we provide approximate models on which the demands are quantified. In particular, we consider the choice of method for the performance- intensive data interpolations. This choice presents a trade-off problem between computational performance and size of working memory. The results of this study will serve as a basis for further, more detailed architecture studies.},
   ISSN = {0190-3918},
   Keywords = {SAR Processing, Back-Projection, Time-Domain Back-Projection, Fast-Factorized Back-Projection, FFBP, GBP, interpolation, parallel algorithms, parallel architectures, radar imaging, real-time systems, storage management, synthetic aperture radarcomplex memory access pattern, computer architecture, flight path error compensation, memory-intensive real-time image forming, parallel algorithm, performance-intensive data interpolation, synthetic aperture radar system},
   Owner = {ofrey},
   Pdf = {../../../docs/ahlanderHellstenLindLindgrenSvensson2007.pdf} 
   }
   




2. Christian Andres, Torben Keil, Raik Herrmann, and Rolf Scheiber. A multiprocessing framework for SAR image processing. In , pages 524-527, July 2007. Keyword(s): SAR Processing, Airborne SAR, application program interfaces, geophysics computing, grid computing, image processing, multiprocessing systems, synthetic aperture radar, workstation clusters, F-SAR, SAR image processing, airborne SAR sensor, application programming interface, cluster grids, different architectures, multiprocessing framework, source code, workstation cluster.

   Abstract:

   This paper introduces a framework developed for image processing of synthetic aperture radar (SAR) images. It encapsulates features of modern hardware architectures, including symmetric and asymmetric multiprocessing, within an easy and intuitive to use application programming interface (API). The multiprocessing part is designed for unified usage of different architectures reaching from multicore processors to cluster of workstations to grids of clusters. So an application using the framework can be ported from one architecture to another without any changes in the source code. The framework builds the bottom layer of the processing system developed for the German Aerospace Center's (DLR) new airborne SAR sensor, the F-SAR.

   
   

   @InProceedings{andresKeilHerrmannScheiber2007:SARMultiProcessingFrame,
   author = {Andres, Christian and Keil, Torben and Herrmann, Raik and Scheiber, Rolf},
   title = {{A multiprocessing framework for SAR image processing}},
   year = {2007},
   month = {jul},
   pages = {524--527},
   abstract = {This paper introduces a framework developed for image processing of synthetic aperture radar (SAR) images. It encapsulates features of modern hardware architectures, including symmetric and asymmetric multiprocessing, within an easy and intuitive to use application programming interface (API). The multiprocessing part is designed for unified usage of different architectures reaching from multicore processors to cluster of workstations to grids of clusters. So an application using the framework can be ported from one architecture to another without any changes in the source code. The framework builds the bottom layer of the processing system developed for the German Aerospace Center's (DLR) new airborne SAR sensor, the F-SAR.},
   doi = {10.1109/IGARSS.2007.4422846},
   journal = {IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2007},
   keywords = {SAR Processing, Airborne SAR, application program interfaces, geophysics computing, grid computing, image processing, multiprocessing systems, synthetic aperture radar, workstation clusters, F-SAR, SAR image processing, airborne SAR sensor, application programming interface, cluster grids, different architectures, multiprocessing framework, source code, workstation cluster},
   pdf = {../../../docs/andresKeilHerrmannScheiber2007.pdf},
   url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=4422846&isnumber=4422708},
   
   }
   




3. Wang Bin, Wang Yanping, Hong Wen, and Wu Yirong. Simulation research of parametric methods for multi-baseline SAR tomography. In Synthetic Aperture Radar, 2007. APSAR 2007. 1st Asian and Pacific Conference on, pages 203-206, November 2007.
   

   @InProceedings{Bin2007,
   Title = {Simulation research of parametric methods for multi-baseline SAR tomography},
   Author = {Wang Bin and Wang Yanping and Hong Wen and Wu Yirong},
   Booktitle = {Synthetic Aperture Radar, 2007. APSAR 2007. 1st Asian and Pacific Conference on},
   Doi = {10.1109/APSAR.2007.4418589},
   Month = nov,
   Pages = {203--206},
   Year = {2007},
   Owner = {ofrey},
   Timestamp = {2009.07.01} 
   }
   




4. E. Candes, N. Braun, and M. Wakin. SPARSE SIGNAL AND IMAGE RECOVERY FROM COMPRESSIVE SAMPLES. In Biomedical Imaging: From Nano to Macro, 2007. ISBI 2007. 4th IEEE International Symposium on, pages 976-979, april 2007. Keyword(s): compressive sampling, data acquisition, image recovery, magnetic resonance imaging, medical imaging, model-based framework, random measurements, random noise-like basis, signal reconstruction, sparse signal recovery, biomedical MRI, biomedical measurement, data acquisition, image coding, image reconstruction, image sampling, medical image processing, random noise, sparse matrices;.

   Abstract:

   In this paper we present an introduction to compressive sampling (CS), an emerging model-based framework for data acquisition and signal recovery based on the premise that a signal having a sparse representation in one basis can be reconstructed from a small number of measurements collected in a second basis that is incoherent with the first. Interestingly, a random noise-like basis will suffice for the measurement process. We will overview the basic CS theory, discuss efficient methods for signal reconstruction, and highlight applications in medical imaging

   
   

   @InProceedings{4193451,
   Title = {SPARSE SIGNAL AND IMAGE RECOVERY FROM COMPRESSIVE SAMPLES},
   Author = {Candes, E. and Braun, N. and Wakin, M.},
   Booktitle = {Biomedical Imaging: From Nano to Macro, 2007. ISBI 2007. 4th IEEE International Symposium on},
   Doi = {10.1109/ISBI.2007.357017},
   Month = {april},
   Pages = {976-979},
   Year = {2007},
   Abstract = {In this paper we present an introduction to compressive sampling (CS), an emerging model-based framework for data acquisition and signal recovery based on the premise that a signal having a sparse representation in one basis can be reconstructed from a small number of measurements collected in a second basis that is incoherent with the first. Interestingly, a random noise-like basis will suffice for the measurement process. We will overview the basic CS theory, discuss efficient methods for signal reconstruction, and highlight applications in medical imaging},
   Keywords = {compressive sampling;data acquisition;image recovery;magnetic resonance imaging;medical imaging;model-based framework;random measurements;random noise-like basis;signal reconstruction;sparse signal recovery;biomedical MRI;biomedical measurement;data acquisition;image coding;image reconstruction;image sampling;medical image processing;random noise;sparse matrices;} 
   }
   




5. Hubert M. J. Cantalloube, Élise Colin-Koeniguer, and Hélène Oriot. High resolution SAR imaging along circular trajectories. In IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2007, pages 850-853, July 2007. Keyword(s): SAR Processing, Autofocus, Phase Gradient Autofocus, PGA, Autofocus by Deterministic Trajectory Triangulation Technique, data acquisition, Motion Compensation, MoComp, Residual Motion Errors, radar antennas, radar polarimetry, remote sensing by radar, synthetic aperture radar, L-band radar, P-band radar, Sweden, X-band sensor, Airborne SAR, aircraft attitude fluctuation, circular trajectories, Non-Linear Flight Track, high resolution SAR imaging, joint FOI-ONERA campaign, narrower antenna pattern, polarimetric full circle radar acquisition, steerable antenna.

   Abstract:

   After a first series of full circle SAR acquisitions in L- and P-bands during a 2004 joint FOI-ONERA campaign in Sweden, ONERA experimented in 2006 high resolution (15 cm) polarimetric, full circle acquisitions in France and Germany using its X-band sensor. In order to cope with narrower antenna pattern and aircraft attitude fluctuations, a steerable antenna was used. Furthermore, an experimental setup for retrieving high accuracy trajectory was installed. This paper describes the processing of this signals.

   
   

   @InProceedings{cantalloubeColinKoeniguerOriot2007:NonLinearFlightTracks,
   Title = {{High resolution SAR imaging along circular trajectories}},
   Author = {Cantalloube, Hubert M. J. and Colin-Koeniguer, \'Elise and Oriot, H\'el\`ene},
   Booktitle = {IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2007},
   Doi = {10.1109/IGARSS.2007.4422930},
   Month = {July},
   Pages = {850-853},
   Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=4422930&isnumber=4422708},
   Year = {2007},
   Abstract = {After a first series of full circle SAR acquisitions in L- and P-bands during a 2004 joint FOI-ONERA campaign in Sweden, ONERA experimented in 2006 high resolution (15 cm) polarimetric, full circle acquisitions in France and Germany using its X-band sensor. In order to cope with narrower antenna pattern and aircraft attitude fluctuations, a steerable antenna was used. Furthermore, an experimental setup for retrieving high accuracy trajectory was installed. This paper describes the processing of this signals.},
   Keywords = {SAR Processing, Autofocus, Phase Gradient Autofocus, PGA, Autofocus by Deterministic Trajectory Triangulation Technique, data acquisition, Motion Compensation, MoComp, Residual Motion Errors, radar antennas, radar polarimetry, remote sensing by radar, synthetic aperture radar, L-band radar, P-band radar, Sweden, X-band sensor, Airborne SAR, aircraft attitude fluctuation, circular trajectories, Non-Linear Flight Track, high resolution SAR imaging, joint FOI-ONERA campaign, narrower antenna pattern, polarimetric full circle radar acquisition, steerable antenna},
   Owner = {ofrey},
   Pdf = {../../../docs/cantalloubeColinKoeniguerOriot2007.pdf} 
   }
   




6. Karlus A. Câmara de Macedo, Rolf Scheiber, and Alberto Moreira. An autofocus approach for residual motion errors with application to airborne repeat-pass SAR interferometry. In IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2007, Barcelona, Spain, pages 4886 - 4889, July 2007. Keyword(s): SAR Processing, Autofocus, Residual Motion Errors, WPCA, Weighted PCA, Weighted Phase Curvature Autofocus, Phase Curvature Autofocus, PCA, Phase Gradient Autofocus, PGA, Repeat-Pass Interferometry, Interferometry, E-SAR, airborne SAR, Baseline Calibration, Tomography, SAR Tomography.

   Abstract:

   Airborne repeat-pass SAR data are very sensible to sub-wavelength deviations from the reference track. To enable repeat-pass interferometry a high-precision navigation system is needed. Due to the limit of accuracy of such systems, deviations in the order of centimeters remain between the nominal and the processed reference track causing mainly undesirable phase undulations and misregistration in the interferograms, referred as residual motion errors. Up to now only interferometric approaches, as multi-squint, are used to estimate those deviations to compensate for such residuals. In this paper we present for the first time the use of the Autofocus technique for residual motion errors. A very robust autofocus technique has to be used since the accuracy of the estimated motion has to be at millimeter scale. Because we deal with low-altitude-stripmap mode data we propose a new robust autofocus technique based on the WLS (Weighted Least-Squares) phase estimation and Phase Curvature Autofocus (PCA) extended to the rangedependent case. We call this new technique WPCA (Weighted PCA). While the multi-squint approach is only able to estimate the baseline variation from coregistered images, the autofocus approach has the advantage of being able to estimate motion deviations independendtly for each image. Repeat-pass data of the E-SAR system of the German Aerospace Center (DLR) are used to demostrate the performance of the proposed approach.

   
   

   @InProceedings{deMacedoScheiberMoreira2007:Autofocus,
   Title = {{An autofocus approach for residual motion errors with application to airborne repeat-pass SAR interferometry}},
   Author = {C{\^a}mara de Macedo, Karlus A. and Scheiber, Rolf and Moreira, Alberto},
   Booktitle = {IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2007},
   Month = {July},
   Pages = {4886 - 4889},
   Url = {http://www.ieeexplore.ieee.org//iel5/4422707/4422708/04423956.pdf},
   Year = {2007},
   Abstract = {Airborne repeat-pass SAR data are very sensible to sub-wavelength deviations from the reference track. To enable repeat-pass interferometry a high-precision navigation system is needed. Due to the limit of accuracy of such systems, deviations in the order of centimeters remain between the nominal and the processed reference track causing mainly undesirable phase undulations and misregistration in the interferograms, referred as residual motion errors. Up to now only interferometric approaches, as multi-squint, are used to estimate those deviations to compensate for such residuals. In this paper we present for the first time the use of the Autofocus technique for residual motion errors. A very robust autofocus technique has to be used since the accuracy of the estimated motion has to be at millimeter scale. Because we deal with low-altitude-stripmap mode data we propose a new robust autofocus technique based on the WLS (Weighted Least-Squares) phase estimation and Phase Curvature Autofocus (PCA) extended to the rangedependent case. We call this new technique WPCA (Weighted PCA). While the multi-squint approach is only able to estimate the baseline variation from coregistered images, the autofocus approach has the advantage of being able to estimate motion deviations independendtly for each image. Repeat-pass data of the E-SAR system of the German Aerospace Center (DLR) are used to demostrate the performance of the proposed approach.},
   Address = {Barcelona, Spain},
   Keywords = {SAR Processing, Autofocus, Residual Motion Errors, WPCA, Weighted PCA, Weighted Phase Curvature Autofocus, Phase Curvature Autofocus, PCA, Phase Gradient Autofocus, PGA, Repeat-Pass Interferometry, Interferometry, E-SAR, airborne SAR, Baseline Calibration, Tomography, SAR Tomography},
   Owner = {ofrey},
   Pdf = {../../../docs/deMacedoScheiberMoreira2007.pdf} 
   }
   




7. John M. Dow, Ruth E. Neilan, and Chris Rizos. The International GNSS Service (IGS): Preparations for the Coming Decade. In 20th Int. Tech. Meeting of the Satellite Division of the US Inst. of Navigation, 2007. Keyword(s): GNSS, Global Navigation Satellite System, International GNSS Service, IGS, Zenith Tropospheric Delay, ZTD.

   Abstract:

   The International GNSS Service (IGS) is an international activity with more than 200 participating organisations in over 80 countries with a track record of more than 13 years of successful service. The IGS is a service of the International Association of Geodesy (IAG) and primarily supports the scientific research based on, and the analysis of, long-term, highly precise and accurate Earth observations using the technologies of Global Navigation Satellite Systems (GNSS), primarily the U.S. Global Positioning System (GPS). The mission of the IGS, recently revised at the IGS Strategic Planning Meeting held in December 2006, is``to provide the highest-quality GNSS data and products in support of the terrestrial reference frame, Earth rotation, Earth observation and research, positioning, navigation and timing and other applications that benefit society''. The IGS will continue to support the IAG's initiative to coordinate cross-technique global geodesy for the next decade - via the development of the Global Geodetic Observing System (GGOS), which focuses on the needs of global geodesy at the mm-level. The IGS activities are fundamental to scientific disciplines related to climate, weather, sea level change, and space weather. However, the IGS also supports many other applications, including precise navigation, machine automation, and surveying and mapping. This paper will discuss the IGS Strategic Plan and future directions of the globally-coordinated ~400 station IGS network, tracking data and information products, and outline the concerns of a few of its numerous working groups and pilot projects as the world anticipates a truly multi-system GNSS in the coming decade.

   
   

   @InProceedings{dowNeilanRizosGNSS2007IGSpreparationsForComingDecades.pdf,
   author = {Dow, John M. and Neilan, Ruth E. and Rizos, Chris},
   title = {The International GNSS Service (IGS): Preparations for the Coming Decade},
   booktitle = {20th Int. Tech. Meeting of the Satellite Division of the US Inst. of Navigation},
   year = {2007},
   abstract = {The International GNSS Service (IGS) is an international activity with more than 200 participating organisations in over 80 countries with a track record of more than 13 years of successful service. The IGS is a service of the International Association of Geodesy (IAG) and primarily supports the scientific research based on, and the analysis of, long-term, highly precise and accurate Earth observations using the technologies of Global Navigation Satellite Systems (GNSS), primarily the U.S. Global Positioning System (GPS). The mission of the IGS, recently revised at the IGS Strategic Planning Meeting held in December 2006, is``to provide the highest-quality GNSS data and products in support of the terrestrial reference frame, Earth rotation, Earth observation and research, positioning, navigation and timing and other applications that benefit society''. The IGS will continue to support the IAG's initiative to coordinate cross-technique global geodesy for the next decade - via the development of the Global Geodetic Observing System (GGOS), which focuses on the needs of global geodesy at the mm-level. The IGS activities are fundamental to scientific disciplines related to climate, weather, sea level change, and space weather. However, the IGS also supports many other applications, including precise navigation, machine automation, and surveying and mapping. This paper will discuss the IGS Strategic Plan and future directions of the globally-coordinated ~400 station IGS network, tracking data and information products, and outline the concerns of a few of its numerous working groups and pilot projects as the world anticipates a truly multi-system GNSS in the coming decade.},
   file = {:dowNeilanRizosGNSS2007IGSpreparationsForComingDecades.pdf:PDF},
   keywords = {GNSS, Global Navigation Satellite System, International GNSS Service, IGS, Zenith Tropospheric Delay, ZTD},
   owner = {ofrey},
   
   }
   




8. H. Essen, H. H. Fuchs, and A. Pagels. High resolution millimeterwave SAR for the remote sensing of wave patterns. In Proc. IEEE Int. Geosci. Remote Sens. Symp., pages 963-966, July 2007. Keyword(s): SAR Processing, W-Band, airborne radar, clutter, ocean waves, oceanographic equipment, radar polarimetry, remote sensing by radar, sea level, statistical analysis, synthetic aperture radar, Ka-band clutter statistics, MEMPHIS, Multi-frequency Experimental Monopulse High-resolution Interferometric SAR, W-band clutter statistics, frequency 35 GHz, frequency 94 GHz, high resolution millimeterwave SAR, high resolution ocean swell imaging, nonimaging statistical methods, polarimetric millimetric SAR, south Spanish Atlantic coast, synthetic aperture radar, wave pattern remote sensing, Bandwidth, Chirp, Frequency, High-resolution imaging, Polarization, Radar imaging, Remote sensing, Sea measurements, Sea surface, Synthetic aperture radar, K-distribution wave pattern, Millimetre waves, SAR, polarimetry, resolution.

   Abstract:

   High resolution imaging of the ocean swell was performed using data collected with the polarimetric millimetre wave synthetic aperture radar MEMPHIS. The data, representative for a region off the south Spanish Atlantic coast in spring, have been evaluated using imaging and non-imaging statistical methods. The influence of high resolution processing on the clutter statistics for the Ka- and the W-band is discussed.

   
   

   @InProceedings{essenFuchsPagelsIGRARSS2007,
   author = {H. Essen and H. H. Fuchs and A. Pagels},
   booktitle = {Proc. IEEE Int. Geosci. Remote Sens. Symp.},
   title = {High resolution millimeterwave {SAR} for the remote sensing of wave patterns},
   year = {2007},
   month = jul,
   pages = {963-966},
   abstract = {High resolution imaging of the ocean swell was performed using data collected with the polarimetric millimetre wave synthetic aperture radar MEMPHIS. The data, representative for a region off the south Spanish Atlantic coast in spring, have been evaluated using imaging and non-imaging statistical methods. The influence of high resolution processing on the clutter statistics for the Ka- and the W-band is discussed.},
   doi = {10.1109/IGARSS.2007.4422959},
   issn = {2153-6996},
   keywords = {SAR Processing, W-Band, airborne radar;clutter;ocean waves;oceanographic equipment;radar polarimetry;remote sensing by radar;sea level;statistical analysis;synthetic aperture radar;Ka-band clutter statistics;MEMPHIS;Multi-frequency Experimental Monopulse High-resolution Interferometric SAR;W-band clutter statistics;frequency 35 GHz;frequency 94 GHz;high resolution millimeterwave SAR;high resolution ocean swell imaging;nonimaging statistical methods;polarimetric millimetric SAR;south Spanish Atlantic coast;synthetic aperture radar;wave pattern remote sensing;Bandwidth;Chirp;Frequency;High-resolution imaging;Polarization;Radar imaging;Remote sensing;Sea measurements;Sea surface;Synthetic aperture radar;K-distribution wave pattern;Millimetre waves;SAR;polarimetry;resolution},
   owner = {ofrey},
   
   }
   




9. G. Fornaro, F. Lombardini, M. Pardini, F. Serafino, F. Soldovieri, and M. Costantini. Spaceborne multi-dimensional SAR imaging: Current status and perspectives. In Geoscience and Remote Sensing Symposium, 2007. IGARSS 2007. IEEE International, pages 5277-5280, July 2007.
   

   @InProceedings{Fornaro2007,
   Title = {Spaceborne multi-dimensional SAR imaging: Current status and perspectives},
   Author = {Fornaro, G. and Lombardini, F. and Pardini, M. and Serafino, F. and Soldovieri, F. and Costantini, M.},
   Booktitle = {Geoscience and Remote Sensing Symposium, 2007. IGARSS 2007. IEEE International},
   Doi = {10.1109/IGARSS.2007.4424053},
   Month = jul,
   Pages = {5277--5280},
   Year = {2007},
   Owner = {ofrey},
   Timestamp = {2009.07.01} 
   }
   




10. Othmar Frey, Felix Morsdorf, and Erich Meier. Tomographic Processing of Multi-Baseline P-Band SAR Data for Imaging of a Forested Area. In Proc. IEEE Int. Geosci. Remote Sens. Symp., 2007. Keyword(s): SAR Processing, SAR Tomography, Tomographic Processing, Multi-Baseline SAR, Time-Domain Back-Projection, Back-Projection, E-SAR, P-Band, Forestry.

    Abstract:

    Recently, various attempts have been undertaken to obtain information about the structure of forested areas from multi-baseline synthetic aperture radar data. Tomographic processing of such data has been demonstrated but the quality of the focused tomographic image is limited by several factors. In particular Fourier-based focusing methods are susceptible to irregular and sparse sampling, two problems, that are unavoidable in case of multi-pass, multi-baseline SAR data acquired by an airborne system. We propose a tomographic focusing method based on the time-domain back-projection algorithm, which maintains the geometric relationship between the original sensor positions and the imaged target and is therefore able to cope with irregular sampling without introducing any approximations with respect to the geometry. We assess the tomographic focusing quality with the help of the impulse response of simulated point targets and an in-scene corner reflector. And, in particular, preliminary results obtained with the newly acquired P-band tomographic data set consisting of eleven flight tracks are presented.

    
    

    @InProceedings{freyMorsdorfMeier07IGARSS:Tomo,
    author = {Othmar Frey and Felix Morsdorf and Erich Meier},
    title = {{Tomographic Processing of Multi-Baseline P-Band SAR Data for Imaging of a Forested Area}},
    booktitle = {Proc. IEEE Int. Geosci. Remote Sens. Symp.},
    year = {2007},
    abstract = {Recently, various attempts have been undertaken to obtain information about the structure of forested areas from multi-baseline synthetic aperture radar data. Tomographic processing of such data has been demonstrated but the quality of the focused tomographic image is limited by several factors. In particular Fourier-based focusing methods are susceptible to irregular and sparse sampling, two problems, that are unavoidable in case of multi-pass, multi-baseline SAR data acquired by an airborne system. We propose a tomographic focusing method based on the time-domain back-projection algorithm, which maintains the geometric relationship between the original sensor positions and the imaged target and is therefore able to cope with irregular sampling without introducing any approximations with respect to the geometry. We assess the tomographic focusing quality with the help of the impulse response of simulated point targets and an in-scene corner reflector. And, in particular, preliminary results obtained with the newly acquired P-band tomographic data set consisting of eleven flight tracks are presented.},
    file = {:freyMorsdorfMeier07IGARSS.pdf:PDF},
    keywords = {SAR Processing, SAR Tomography, Tomographic Processing, Multi-Baseline SAR, Time-Domain Back-Projection, Back-Projection, E-SAR, P-Band, Forestry},
    owner = {ofrey},
    pdf = {http://www.ifu-sar.ethz.ch/otfrey/SARbibliography/myPapers/freyMorsdorfMeier07IGARSS.pdf},
    url = {http://ieeexplore.ieee.org/iel5/4422707/4422708/04422753.pdf},
    
    }
    




11. Othmar Frey, Felix Morsdorf, and Erich Meier. Tomographic SAR Imaging of a Forested Area by Time-Domain Back-Projection. In M.E. Schaepman, S. Liang, N.E. Groot, and M. Kneubühler, editors, 10th Intl. Symposium on Physical Measurements and Spectral Signatures in Remote Sensing, volume XXXVI, 2007. Intl. Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Keyword(s): SAR Processing, SAR Tomography, Tomographic Processing, Multi-Baseline SAR, Time-Domain Back-Projection, Back-Projection, E-SAR, P-Band, Forestry.

    Abstract:

    Recently, various attempts have been undertaken to retrieve information about the three-dimensional structure of vegetation from multibaseline synthetic aperture radar data. Although tomographic processing of such data has been demonstrated, yet, there are still several problems that limit the focusing quality. In particular, the frequency-domain based focusing methods are susceptible to irregular and sparse sampling, two problems, which are unavoidable in case of multi-pass, multi-baseline radar data acquired by an airborne system. We propose a time-domain back-projection algorithm, which maintains the original geometric relationship between the original sensor positions and the imaged target and is therefore able to cope with irregular and sparse sampling without introducing any geometric approximations. Preliminary results obtained with a newly acquired P-band tomographic data set consisting of eleven flight tracks are shown and discussed.

    
    

    @InProceedings{freyMorsdorfMeierISPMSRS2007:Tomo,
    author = {Othmar Frey and Felix Morsdorf and Erich Meier},
    title = {{Tomographic SAR Imaging of a Forested Area by Time-Domain Back-Projection}},
    booktitle = {10th Intl. Symposium on Physical Measurements and Spectral Signatures in Remote Sensing},
    year = {2007},
    editor = {M.E. Schaepman and S. Liang and N.E. Groot and M. Kneub{\"u}hler},
    volume = {XXXVI},
    number = {7/C50},
    organization = {Intl. Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences},
    abstract = {Recently, various attempts have been undertaken to retrieve information about the three-dimensional structure of vegetation from multibaseline synthetic aperture radar data. Although tomographic processing of such data has been demonstrated, yet, there are still several problems that limit the focusing quality. In particular, the frequency-domain based focusing methods are susceptible to irregular and sparse sampling, two problems, which are unavoidable in case of multi-pass, multi-baseline radar data acquired by an airborne system. We propose a time-domain back-projection algorithm, which maintains the original geometric relationship between the original sensor positions and the imaged target and is therefore able to cope with irregular and sparse sampling without introducing any geometric approximations. Preliminary results obtained with a newly acquired P-band tomographic data set consisting of eleven flight tracks are shown and discussed.},
    file = {:freyMorsdorfMeierISPMSRS2007.pdf:PDF},
    keywords = {SAR Processing, SAR Tomography, Tomographic Processing, Multi-Baseline SAR, Time-Domain Back-Projection, Back-Projection, E-SAR, P-Band, Forestry},
    owner = {ofrey},
    pdf = {http://www.ifu-sar.ethz.ch/otfrey/SARbibliography/myPapers/freyMorsdorfMeierISPMSRS2007.pdf},
    url = {http://skgr0103.wur.nl/~schae001/ispmsrs/P23_Frey_SAR.pdf},
    
    }
    




12. F. Gumbmann, H. P. Tran, J. Weinzierl, and L. P. Schmidt. Optimization of a fast scanning millimetre-wave short range SAR imaging system. In Proc. European Radar Conference, pages 24-27, October 2007. Keyword(s): SAR Processing, W-Band, frequency response, millimetre wave imaging, radar imaging, synthetic aperture radar, waveguide couplers, SAR algorithms, W-band short range imaging system, active imaging system, broadband frequency response, fast scanning millimetre-wave short range SAR imaging system, high directivity waveguide coupler, monostatic virtual antenna concept, nondestructive testing applications, quasioptical broadband diplexer, receiver channel, security applications, synthetic aperture radar, transmitter channel, unfocused measurement setup, Antenna measurements, Focusing, Frequency measurement, Frequency response, Nondestructive testing, Pixel, Radar polarimetry, Security, System testing, Transmitters.

    Abstract:

    This paper presents the development of a W-band short range imaging system for security and non-destructive testing applications, which uses an unfocused measurement setup employing SAR algorithms in order to focus the image numerically. The active imaging system offers the possibility to get a broadband frequency response from each pixel in the measurement plane. For real-time applications a fast scanning, monostatic virtual antenna concept has been developed and optimized. The monostatic setup is demonstrated in two different configurations, on the one hand using a quasioptical, broadband diplexer with high decoupling between transmitter and receiver channel and on the other hand a very compact setup using a commercially available high directivity waveguide coupler. The measurement setups are compared with special respect to their RF-performance. Experimental results on specific test objects are presented to prove the performance of the fast short range SAR imaging system.

    
    

    @InProceedings{gumbmannTranWeinzierlSchmidtEuRAD2007WBandRadar,
    author = {F. Gumbmann and H. P. Tran and J. Weinzierl and L. P. Schmidt},
    booktitle = {Proc. European Radar Conference},
    title = {Optimization of a fast scanning millimetre-wave short range SAR imaging system},
    year = {2007},
    month = oct,
    pages = {24-27},
    abstract = {This paper presents the development of a W-band short range imaging system for security and non-destructive testing applications, which uses an unfocused measurement setup employing SAR algorithms in order to focus the image numerically. The active imaging system offers the possibility to get a broadband frequency response from each pixel in the measurement plane. For real-time applications a fast scanning, monostatic virtual antenna concept has been developed and optimized. The monostatic setup is demonstrated in two different configurations, on the one hand using a quasioptical, broadband diplexer with high decoupling between transmitter and receiver channel and on the other hand a very compact setup using a commercially available high directivity waveguide coupler. The measurement setups are compared with special respect to their RF-performance. Experimental results on specific test objects are presented to prove the performance of the fast short range SAR imaging system.},
    doi = {10.1109/EURAD.2007.4404927},
    keywords = {SAR Processing, W-Band, frequency response;millimetre wave imaging;radar imaging;synthetic aperture radar;waveguide couplers;SAR algorithms;W-band short range imaging system;active imaging system;broadband frequency response;fast scanning millimetre-wave short range SAR imaging system;high directivity waveguide coupler;monostatic virtual antenna concept;nondestructive testing applications;quasioptical broadband diplexer;receiver channel;security applications;synthetic aperture radar;transmitter channel;unfocused measurement setup;Antenna measurements;Focusing;Frequency measurement;Frequency response;Nondestructive testing;Pixel;Radar polarimetry;Security;System testing;Transmitters},
    owner = {ofrey},
    
    }
    




13. Wang Jinfeng, Zhou Peng, and Pi Yiming. SAR tomography imaging based on high-order spectrum analysis. In Synthetic Aperture Radar, 2007. APSAR 2007. 1st Asian and Pacific Conference on, pages 364-367, November 2007.
    

    @InProceedings{Jinfeng2007,
    Title = {SAR tomography imaging based on high-order spectrum analysis},
    Author = {Wang Jinfeng and Zhou Peng and Pi Yiming},
    Booktitle = {Synthetic Aperture Radar, 2007. APSAR 2007. 1st Asian and Pacific Conference on},
    Doi = {10.1109/APSAR.2007.4418627},
    Month = nov,
    Pages = {364--367},
    Year = {2007},
    Owner = {ofrey} 
    }
    




14. M. Lachaise, Michael Eineder, and Thomas Fritz. Multi baseline SAR acquisition concepts and phase unwrapping algorithms for the TanDEM-X mission. In Proc. IEEE Int. Geosci. Remote Sens. Symp., pages 5272-5276, July 2007. Keyword(s): TerraSAR-X, TanDEM-X, AD 2009, HRTI-3 specifications, TanDEM-X mission, TerraSAR-X add-on for Digital Elevation Measurement, bistatic mode interferometric SAR data, controlled helix two satellite configuration, digital elevation model, global DEM, global land surface, multibaseline SAR acquisition concept, multibaseline SAR phase unwrapping algorithm, artificial satellites, data acquisition, digital elevation models, geophysical signal processing, radar interferometry, radar signal processing, remote sensing by radar, spaceborne radar, synthetic aperture radar.

    Abstract:

    The TanDEM-X (TerraSAR-X add-on for Digital Elevation Measurement) mission will start in 2009 with the aim of generating a global Digital Elevation Model with high accuracy corresponding to HRTI-3 specifications (12 m posting, 2 m relative point-to-point height accuracy for flat terrain). To achieve this goal, a second satellite similar to TerraSAR-X will fly close to TerraSAR-X in a controlled Helix configuration for 3 years to jointly acquire interferometric SAR data in bistatic mode. According to the current mission concept, there will be at least two complete coverages of the global land surface, each one running one year. The different coverages will have different heights of ambiguity to allow multi-baseline phase unwrapping. For the sake of a homogenous data quality the second acquisition will be shifted by half the swath width with respect to the first coverage. Finally difficult terrain will be covered two more times with different acquisition geometries (i.e. different look direction and/or incidence angles). This paper presents first study results of phase unwrapping algorithms foreseen to process SAR data from the bistatic TanDEM-X configuration.

    
    

    @InProceedings{lachaiseEinederFritz2007,
    author = {Lachaise, M. and Eineder, Michael and Fritz, Thomas},
    title = {Multi baseline {SAR} acquisition concepts and phase unwrapping algorithms for the {TanDEM-X} mission},
    booktitle = {Proc. IEEE Int. Geosci. Remote Sens. Symp.},
    year = {2007},
    pages = {5272-5276},
    month = jul,
    abstract = {The TanDEM-X (TerraSAR-X add-on for Digital Elevation Measurement) mission will start in 2009 with the aim of generating a global Digital Elevation Model with high accuracy corresponding to HRTI-3 specifications (12 m posting, 2 m relative point-to-point height accuracy for flat terrain). To achieve this goal, a second satellite similar to TerraSAR-X will fly close to TerraSAR-X in a controlled Helix configuration for 3 years to jointly acquire interferometric SAR data in bistatic mode. According to the current mission concept, there will be at least two complete coverages of the global land surface, each one running one year. The different coverages will have different heights of ambiguity to allow multi-baseline phase unwrapping. For the sake of a homogenous data quality the second acquisition will be shifted by half the swath width with respect to the first coverage. Finally difficult terrain will be covered two more times with different acquisition geometries (i.e. different look direction and/or incidence angles). This paper presents first study results of phase unwrapping algorithms foreseen to process SAR data from the bistatic TanDEM-X configuration.},
    doi = {10.1109/IGARSS.2007.4424052},
    file = {:lachaiseEinederFritz2007.pdf:PDF},
    keywords = {TerraSAR-X, TanDEM-X, AD 2009;HRTI-3 specifications;TanDEM-X mission;TerraSAR-X add-on for Digital Elevation Measurement;bistatic mode interferometric SAR data;controlled helix two satellite configuration;digital elevation model;global DEM;global land surface;multibaseline SAR acquisition concept;multibaseline SAR phase unwrapping algorithm;artificial satellites;data acquisition;digital elevation models;geophysical signal processing;radar interferometry;radar signal processing;remote sensing by radar;spaceborne radar;synthetic aperture radar},
    owner = {ofrey},
    pdf = {../../../docs/lachaiseEinederFritz2007.pdf},
    url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4424052},
    
    }
    




15. F. Lombardini. New potentials of differential SAR tomography: Volumetric differential interferometry and robust DEM generation. In Geoscience and Remote Sensing Symposium, 2007. IGARSS 2007. IEEE International, pages 5281-5284, July 2007.
    

    @InProceedings{Lombardini2007b,
    Title = {New potentials of differential SAR tomography: Volumetric differential interferometry and robust DEM generation},
    Author = {Lombardini, F.},
    Booktitle = {Geoscience and Remote Sensing Symposium, 2007. IGARSS 2007. IEEE International},
    Doi = {10.1109/IGARSS.2007.4424054},
    Month = jul,
    Pages = {5281--5284},
    Year = {2007},
    Owner = {ofrey},
    Timestamp = {2009.07.01} 
    }
    




16. Fabrizio Lombardini, Matteo Pardini, and Fulvio Gini. Sector interpolation for 3D SAR imaging with baseline diversity data. In Waveform Diversity and Design Conference, 2007. International, pages 297-301, June 2007.
    

    @InProceedings{Lombardini2007a,
    Title = {Sector interpolation for 3D SAR imaging with baseline diversity data},
    Author = {Lombardini, Fabrizio and Pardini, Matteo and Gini, Fulvio},
    Booktitle = {Waveform Diversity and Design Conference, 2007. International},
    Doi = {10.1109/WDDC.2007.4339430},
    Month = jun,
    Pages = {297--301},
    Year = {2007},
    Owner = {ofrey} 
    }
    




17. Fabrizio Lombardini, Ludwig Rössing, Joachim H. G. Ender, and F. Viviani. Towards a Complete Processing Chain of Multibaseline Airborne InSAR Data for Layover Scatterers Separation. In Urban Remote Sensing Joint Event, 2007, pages 1-6, April 2007.

    Abstract:

    Interest is continuing to grow in exploiting the advanced multibaseline operation of synthetic aperture radar interferometry (InSAR) to solve layover effects, that can degrade conventional InSAR topographic mapping. In this work we report about experiments of the functionality of layover-free or higher-order interferometry with the dual-baseline single-pass SAR interferometer AER-II. Estimation of the number of multiple layover scatterers, i.e. of the interferometric order, and model-based spatial spectral estimation are integrated to process the three-antenna non uniform array data. Results are discussed for a bridge over the valley test site.

    
    

    @InProceedings{LombardiniRoessingEnderViviani2007a:Tomo,
    Title = {Towards a Complete Processing Chain of Multibaseline Airborne InSAR Data for Layover Scatterers Separation},
    Author = {Lombardini, Fabrizio and R{\"o}ssing, Ludwig and Joachim H. G. Ender and Viviani, F.},
    Booktitle = {Urban Remote Sensing Joint Event, 2007},
    Doi = {10.1109/URS.2007.371875},
    Month = apr,
    Pages = {1--6},
    Url = {http://ieeexplore.ieee.org/iel5/4234358/4234359/04234474.pdf},
    Year = {2007},
    Abstract = {Interest is continuing to grow in exploiting the advanced multibaseline operation of synthetic aperture radar interferometry (InSAR) to solve layover effects, that can degrade conventional InSAR topographic mapping. In this work we report about experiments of the functionality of layover-free or higher-order interferometry with the dual-baseline single-pass SAR interferometer AER-II. Estimation of the number of multiple layover scatterers, i.e. of the interferometric order, and model-based spatial spectral estimation are integrated to process the three-antenna non uniform array data. Results are discussed for a bridge over the valley test site.},
    Owner = {ofrey},
    Pdf = {../../../docs/LombardiniRoessingEnderViviani2007a.pdf} 
    }
    




18. Andrea Monti-Guarnieri and Stefano Tebaldini. A new framework for multi-pass SAR interferometry with distributed targets. In IEEE International Geoscience and Remote Sensing Symposium, pages 5289-5293, July 2007. Keyword(s): Monte Carlo methods, digital elevation models, radar interferometry, remote sensing by radar, spaceborne radar, synthetic aperture radar, topography (Earth)DEM, InSAR, LOS displacement, Monte Carlo simulation, distributed scattering, multipass spaceborne SAR interferometry, repeated pass ENVISAT images, residual topography, synthetic aperture radar interferometry.

    Abstract:

    This paper focuses on multi-pass spaceborne synthetic aperture radar interferometry (InSAR) in presence of distributed scattering, paying particular attention to the role of target decorrelation in the estimation process. This phenomenon is accounted for by splitting the analysis into two steps. In the first step we estimate the interferometric phases from the data, while in the second step we use these phases to retrieve the physical parameters of interest, such as LOS displacement and residual topography. This approach is suited both to derive the performances of InSAR with different decorrelation models and for providing an actual estimate of LOS motion and DEM. Results achieved from Monte-Carlo simulations and a set of repeated pass ENVISAT images are shown.

    
    

    @InProceedings{montiGuarnieriTebaldiniIGARSS2007:Tomo,
    Title = {A new framework for multi-pass {SAR} interferometry with distributed targets},
    Author = {Monti-Guarnieri, Andrea and Tebaldini, Stefano},
    Booktitle = {IEEE International Geoscience and Remote Sensing Symposium},
    Doi = {10.1109/IGARSS.2007.4424056},
    Month = {jul},
    Pages = {5289-5293},
    Url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4424056&isnumber=4422708},
    Year = {2007},
    Abstract = {This paper focuses on multi-pass spaceborne synthetic aperture radar interferometry (InSAR) in presence of distributed scattering, paying particular attention to the role of target decorrelation in the estimation process. This phenomenon is accounted for by splitting the analysis into two steps. In the first step we estimate the interferometric phases from the data, while in the second step we use these phases to retrieve the physical parameters of interest, such as LOS displacement and residual topography. This approach is suited both to derive the performances of InSAR with different decorrelation models and for providing an actual estimate of LOS motion and DEM. Results achieved from Monte-Carlo simulations and a set of repeated pass ENVISAT images are shown.},
    Keywords = {Monte Carlo methods, digital elevation models, radar interferometry, remote sensing by radar, spaceborne radar, synthetic aperture radar, topography (Earth)DEM, InSAR, LOS displacement, Monte Carlo simulation, distributed scattering, multipass spaceborne SAR interferometry, repeated pass ENVISAT images, residual topography, synthetic aperture radar interferometry},
    Owner = {ofrey},
    Pdf = {../../../docs/montiGuarnieriTebaldiniIGARSS2007.pdf} 
    }
    




19. Keith Morrison, Helmut Rott, Thomas Nagler, Helge Rebhan, and Patrick Wursteisen. The SARALPS-2007 measurement campaign on X- and Ku-Band Backscatter of snow. In Proc. IEEE Int. Geosci. Remote Sens. Symp., pages 1207-1210, July 2007. Keyword(s): snow, radar interferometry, radar polarimetry, snow, synthetic aperture radar, AD 2006 to 2007, Austrian Alps, InSAR mode, Innsbruck, SARALPS-2007 measurement campaign, active microwave sensors, polarimetric backscatter, snow parameters, snow water equivalent, spaceborne scatterometry, Backscatter, Frequency, Hydrologic measurements, Hydrology, Microwave sensors, Radar measurements, Snow, Spaceborne radar, Synthetic aperture radar, System testing, Synthetic aperture radar, ice, snow.

    Abstract:

    The retrieval of snow parameters, and snow water equivalent in particular, are key parameters in hydrology and climate research. Theory, ground-based signature research and analysis of spaceborne scatterometry suggests that the high- frequency combination of Ku- and X-band active microwave sensors is an excellent tool for the retrieval of snow physical properties. In order to validate this, a snow measurement campaign was carried out with the University of Cranfield's portable Ground-Based Synthetic Aperture Radar (GB-SAR) System during the winter of 2006/7 at two test-sites in the Austrian Alps close to Innsbruck. Fully polarimetric X-and Ku-band backscatter signatures were acquired over a range of incidence angles (~20deg-70deg), with the active sensor operating predominately in SAR mode, but occasionally also in InSAR mode. Microwave signatures and snow properties were measured on seven different dates. Detailed complementary meteorological and snow metamorphic conditions were also recorded.

    
    

    @InProceedings{morrisonRottNaglerRebhanWursteisenIGARSS2007XandKuBandBackscatterSnow,
    author = {Morrison, Keith and Rott, Helmut and Nagler, Thomas and Rebhan, Helge and Wursteisen, Patrick},
    title = {The {SARALPS-2007} measurement campaign on {X-} and {Ku}-Band Backscatter of snow},
    booktitle = {Proc. IEEE Int. Geosci. Remote Sens. Symp.},
    year = {2007},
    pages = {1207-1210},
    month = jul,
    abstract = {The retrieval of snow parameters, and snow water equivalent in particular, are key parameters in hydrology and climate research. Theory, ground-based signature research and analysis of spaceborne scatterometry suggests that the high- frequency combination of Ku- and X-band active microwave sensors is an excellent tool for the retrieval of snow physical properties. In order to validate this, a snow measurement campaign was carried out with the University of Cranfield's portable Ground-Based Synthetic Aperture Radar (GB-SAR) System during the winter of 2006/7 at two test-sites in the Austrian Alps close to Innsbruck. Fully polarimetric X-and Ku-band backscatter signatures were acquired over a range of incidence angles (~20deg-70deg), with the active sensor operating predominately in SAR mode, but occasionally also in InSAR mode. Microwave signatures and snow properties were measured on seven different dates. Detailed complementary meteorological and snow metamorphic conditions were also recorded.},
    doi = {10.1109/IGARSS.2007.4423022},
    file = {:morrisonRottNaglerRebhanWursteisenIGARSS2007XandKuBandBackscatterSnow.pdf:PDF},
    keywords = {snow, radar interferometry;radar polarimetry;snow;synthetic aperture radar;AD 2006 to 2007;Austrian Alps;InSAR mode;Innsbruck;SARALPS-2007 measurement campaign;active microwave sensors;polarimetric backscatter;snow parameters;snow water equivalent;spaceborne scatterometry;Backscatter;Frequency;Hydrologic measurements;Hydrology;Microwave sensors;Radar measurements;Snow;Spaceborne radar;Synthetic aperture radar;System testing;Synthetic aperture radar;ice;snow},
    pdf = {../../../docs/morrisonRottNaglerRebhanWursteisenIGARSS2007XandKuBandBackscatterSnow.pdf},
    
    }
    




20. Matteo Nannini and Rolf Scheiber. Height dependent motion compensation and coregistration for airborne SAR tomography. In International Geoscience and Remote Sensing Symposium, 2007. IGARSS 2007, pages 5041-5044, July 2007. Keyword(s): SAR Processing, SAR Tomography, Tomography, geophysical signal processing, image registration, Motion Compensation, radar imaging, remote sensing by radar, synthetic aperture radar2D SAR repeat-pass processing, E-SAR system, L-Band, German Aerospace Centre, SAR imaging, airborne SAR tomography, data acquisition, height dependent motion compensation, image coregistration, multiple phase center separation, processing correction, tomogram quality, volumetric target.

    Abstract:

    SAR tomography (SARTom) is an imaging technique that allows multiple phase centers separation in the vertical (height) direction. It is performed after standard 2D SAR repeat-pass processing and operates on a stack of coregistered SAR images. Theoretically, the coregistration between two images is height dependent and the use of a reference height (or a DEM) is needed, although not ideal in the case of volumetric target (multiple phase centers in one resolution cell). In this paper, the drawbacks related to the choice of this reference in a tomographic context are analysed and a height dependent coregistration approach is proposed. In order to do this, it is also necessary to remove processing corrections related to the reference height, such as motion compensation, and make them height dependent. The inclusion of the height dependency during the tomographic SAR processing results in a better quality of the final tomograms in terms of pseudo-power and phase centers separation. The results of the proposed approach are validated on real data acquired by the E-SAR system of the German Aerospace Centre - DLR.

    
    

    @InProceedings{nanniniScheiber2007:Tomo,
    Title = {{Height dependent motion compensation and coregistration for airborne SAR tomography}},
    Author = {Nannini, Matteo and Scheiber, Rolf},
    Booktitle = {International Geoscience and Remote Sensing Symposium, 2007. IGARSS 2007},
    Doi = {10.1109/IGARSS.2007.4423994},
    Month = {July},
    Pages = {5041-5044},
    Url = {http://ieeexplore.ieee.org/iel5/4422707/4422708/04423994.pdf},
    Year = {2007},
    Abstract = {SAR tomography (SARTom) is an imaging technique that allows multiple phase centers separation in the vertical (height) direction. It is performed after standard 2D SAR repeat-pass processing and operates on a stack of coregistered SAR images. Theoretically, the coregistration between two images is height dependent and the use of a reference height (or a DEM) is needed, although not ideal in the case of volumetric target (multiple phase centers in one resolution cell). In this paper, the drawbacks related to the choice of this reference in a tomographic context are analysed and a height dependent coregistration approach is proposed. In order to do this, it is also necessary to remove processing corrections related to the reference height, such as motion compensation, and make them height dependent. The inclusion of the height dependency during the tomographic SAR processing results in a better quality of the final tomograms in terms of pseudo-power and phase centers separation. The results of the proposed approach are validated on real data acquired by the E-SAR system of the German Aerospace Centre - DLR.},
    Keywords = {SAR Processing, SAR Tomography, Tomography, geophysical signal processing, image registration, Motion Compensation, radar imaging, remote sensing by radar, synthetic aperture radar2D SAR repeat-pass processing, E-SAR system, L-Band, German Aerospace Centre, SAR imaging, airborne SAR tomography, data acquisition, height dependent motion compensation, image coregistration, multiple phase center separation, processing correction, tomogram quality, volumetric target},
    Owner = {ofrey},
    Pdf = {../../../docs/nanniniScheiberTomo2007.pdf} 
    }
    




21. C. Neumann, G. Weiss, A. Wahlen, and T. Brehm. Ground surveillance with mmW radar for border control and camp protection applications. In Proc. European Microwave Conference, pages 700-703, October 2007. Keyword(s): SAR Processing, W-Band, Airborne SAR, UAV, Fraunhofer, military radar, search radar, terrorism, automatic detection, automatic recognition, border control, camp protection application, ground surveillance, light weight miniature sensors, millimetre wave region, mmW radar, moving hostile objects, peace enforcing missions, peacekeeping missions, portable 35-GHz radar, terrorism, Bandwidth, Costs, Meteorological radar, Protection, Radar applications, Radar clutter, Signal resolution, Snow, Surveillance, Terrorism.

    Abstract:

    In a world where terrorism is threatening as well civilian people as the forces involved in peacekeeping and peace enforcing missions, the protection of borderlines of regions of interest as well as military camps is a necessary demand. To maintain day- and night performance under adverse weather conditions especially with the ability to cope with dust, fog and haze or snow, radar sensors are under development. Especially the millimetre wave region offers the additional advantage of small, light weight miniature sensors with the capability to accommodate a high signal bandwidth and thus high range resolution. To demonstrate these capabilities for both millimetre wave regions, Ka- and W-band, experiments were conducted jointly by EADS, Ulm, and FGAN-FHR, Wachtberg. A low cost and easily portable 35-GHz radar, originally designed for SAR applications in small UAVs, is used for automatic detection and recognition of moving hostile objects like persons and vehicles at distances of several kilometres in a strong ground clutter environment. A similar FM-CW radar operating at 94 GHz has been used under comparable environmental conditions to gather data at this radar band. It could be shown that possible foes will be recognized and exactly localized in range, azimuth and velocity. Possible applications of such sensors embedded in protection system concepts are presented as well as signature examples, algorithm approaches and results from outdoor experiments.

    
    

    @InProceedings{neumannWeissWahlenBrehmEuMW2007WBandRadar,
    author = {C. Neumann and G. Weiss and A. Wahlen and T. Brehm},
    booktitle = {Proc. European Microwave Conference},
    title = {Ground surveillance with mmW radar for border control and camp protection applications},
    year = {2007},
    month = oct,
    pages = {700-703},
    abstract = {In a world where terrorism is threatening as well civilian people as the forces involved in peacekeeping and peace enforcing missions, the protection of borderlines of regions of interest as well as military camps is a necessary demand. To maintain day- and night performance under adverse weather conditions especially with the ability to cope with dust, fog and haze or snow, radar sensors are under development. Especially the millimetre wave region offers the additional advantage of small, light weight miniature sensors with the capability to accommodate a high signal bandwidth and thus high range resolution. To demonstrate these capabilities for both millimetre wave regions, Ka- and W-band, experiments were conducted jointly by EADS, Ulm, and FGAN-FHR, Wachtberg. A low cost and easily portable 35-GHz radar, originally designed for SAR applications in small UAVs, is used for automatic detection and recognition of moving hostile objects like persons and vehicles at distances of several kilometres in a strong ground clutter environment. A similar FM-CW radar operating at 94 GHz has been used under comparable environmental conditions to gather data at this radar band. It could be shown that possible foes will be recognized and exactly localized in range, azimuth and velocity. Possible applications of such sensors embedded in protection system concepts are presented as well as signature examples, algorithm approaches and results from outdoor experiments.},
    doi = {10.1109/EUMC.2007.4405288},
    keywords = {SAR Processing, W-Band, Airborne SAR, UAV, Fraunhofer, military radar;search radar;terrorism;automatic detection;automatic recognition;border control;camp protection application;ground surveillance;light weight miniature sensors;millimetre wave region;mmW radar;moving hostile objects;peace enforcing missions;peacekeeping missions;portable 35-GHz radar;terrorism;Bandwidth;Costs;Meteorological radar;Protection;Radar applications;Radar clutter;Signal resolution;Snow;Surveillance;Terrorism},
    owner = {ofrey},
    
    }
    




22. L. Pipia, X. Fabregas, A. Aguasca, C. Lopez-Martinez, J. J. Mallorqui, and O. Moraline. Polarimetric temporal information for urban deformation map retrieval. In Proc. IEEE Int. Geoscience and Remote Sensing Symp, pages 192-195, July 2007. Keyword(s): GB-SAR, ground-based SAR, terrestrial SAR, radar interferometry, radar polarimetry, synthetic aperture radar, town and country planning, PolSAR, Salient village, UPC RSLab, X-Band ground- based SAR sensor, differential interferometric applications, full scattering matrix, polarimetric persistent scatterers, polarimetric temporal information, urban deformation map retrieval, Fasteners, Geometry, Information retrieval, Interferometry, Laboratories, Polarization, Remote monitoring, Remote sensing, Scattering, Sensor phenomena and characterization.
    

    @InProceedings{Pipia2007,
    author = {L. Pipia and X. Fabregas and A. Aguasca and C. Lopez-Martinez and J. J. Mallorqui and O. Moraline},
    booktitle = {Proc. IEEE Int. Geoscience and Remote Sensing Symp},
    title = {Polarimetric temporal information for urban deformation map retrieval},
    year = {2007},
    month = jul,
    pages = {192--195},
    doi = {10.1109/IGARSS.2007.4422762},
    issn = {2153-6996},
    keywords = {GB-SAR, ground-based SAR, terrestrial SAR, radar interferometry, radar polarimetry, synthetic aperture radar, town and country planning, PolSAR, Salient village, UPC RSLab, X-Band ground- based SAR sensor, differential interferometric applications, full scattering matrix, polarimetric persistent scatterers, polarimetric temporal information, urban deformation map retrieval, Fasteners, Geometry, Information retrieval, Interferometry, Laboratories, Polarization, Remote monitoring, Remote sensing, Scattering, Sensor phenomena and characterization},
    owner = {ofrey},
    
    }
    




23. Pau Prats, Christian Andres, Rolf Scheiber, Karlus A. Câmara de Macedo, Jens Fischer, and Andreas Reigber. Glacier displacement field estimation using airborne SAR interferometry. In IEEE International Geoscience and Remote Sensing Symposium, 2007. IGARSS 2007., pages 2098-2101, July 2007. Keyword(s): SAR Processing, SAR interferometry, InSAR, DInSAR, Spectral Diversity, Residual Motion Errors, Motion Compensation, MoComp, Airborne SAR, ESAR, airborne radar, glaciology, hydrological techniques, radar interferometry, synthetic aperture radar2D displacement map, Aletsch glacier, E-SAR, Experimental SAR, German Aerospace Center, Swiss Alps, across-track displacement, airborne SAR data, airborne, along-track displacement, extended multisquint approach, glacier displacement field estimation, slant-range geometry.

    Abstract:

    This paper deals with the methodology in the processing of airborne SAR data to measure glacier displacement fields. The possibility to retrieve a 2D displacement map of the deformation in slant-range geometry with an airborne platform is discussed. A new extended multisquint approach is proposed to simultaneously estimate residual motion errors and the along-track displacement of the glacier, while the across-track displacement is obtained by means of differential interferomatry. Experimental results are shown with data acquired by the Experimental SAR (E-SAR) of the German Aerospace Center over the Aletsch glacier in the Swiss Alps.

    
    

    @InProceedings{pratsAndresScheiberdeMacedoFischerReigber2007:DInSARAletsch,
    author = {Prats, Pau and Andres, Christian and Scheiber, Rolf and C\^amara de Macedo, Karlus A. and Fischer, Jens and Reigber, Andreas},
    booktitle = {IEEE International Geoscience and Remote Sensing Symposium, 2007. IGARSS 2007.},
    title = {{Glacier displacement field estimation using airborne SAR interferometry}},
    year = {2007},
    month = {jul},
    pages = {2098--2101},
    abstract = {This paper deals with the methodology in the processing of airborne SAR data to measure glacier displacement fields. The possibility to retrieve a 2D displacement map of the deformation in slant-range geometry with an airborne platform is discussed. A new extended multisquint approach is proposed to simultaneously estimate residual motion errors and the along-track displacement of the glacier, while the across-track displacement is obtained by means of differential interferomatry. Experimental results are shown with data acquired by the Experimental SAR (E-SAR) of the German Aerospace Center over the Aletsch glacier in the Swiss Alps.},
    doi = {10.1109/IGARSS.2007.4423247},
    keywords = {SAR Processing, SAR interferometry, InSAR, DInSAR, Spectral Diversity, Residual Motion Errors, Motion Compensation, MoComp, Airborne SAR, ESAR, airborne radar, glaciology, hydrological techniques, radar interferometry, synthetic aperture radar2D displacement map, Aletsch glacier, E-SAR, Experimental SAR, German Aerospace Center, Swiss Alps, across-track displacement, airborne SAR data, airborne, along-track displacement, extended multisquint approach, glacier displacement field estimation, slant-range geometry},
    owner = {ofrey},
    pdf = {../../../docs/pratsAndresScheiberdeMacedoFischerReigber2007.pdf},
    url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=4423247&isnumber=4422708},
    
    }
    




24. Rolf Scheiber, Pau Prats, Matteo Nannini, Karlus A. Câmara de Macedo, Christian Andres, Jens Fischer, and Ralf Horn. Advances in airborne SAR interferometry using the experimental SAR system of DLR. In European Radar Conference, EuRAD 2007., 2007. Keyword(s): SAR Processing, SAR Tomography, Tomography, InSAR, Interferometry, PTA, SATA, Residual Motion Errors, Motion Compensation, DInSAR, Differential InSAR, Differential Interferometry, E-SAR.

    Abstract:

    During recent years the experimental SAR (E-SAR) system of the German Aerospace Center (DLR) has continuously been operated to acquire data for different scientific applications in forestry, agriculture and glaciology. In this context, the data where mainly used to develop new scattering models in preparation of future space-borne missions posing increasing accuracy requirements especially for the processing of repeat-pass interferometric data. Also direct model-free methods like differential SAR interferometry for measuring displacements in the order of the wavelength or SAR tomography for real 3D microwave imaging of scattering volumes determined the development of advanced and very accurate motion compensation techniques. This paper first gives an overview of the updates of the E-SAR system performed during the last couple of years and then focusses on the recently developed airborne interferometric processing methods and their applications.

    
    

    @InProceedings{scheiberPratsNanninideMacedoAndresFischerHorn2007:ESAR,
    Title = {{Advances in airborne SAR interferometry using the experimental SAR system of DLR}},
    Author = {Scheiber, Rolf and Prats, Pau and Nannini, Matteo and C{\^a}mara de Macedo, Karlus A. and Andres, Christian and Fischer, Jens and Horn, Ralf},
    Booktitle = {European Radar Conference, EuRAD 2007.},
    Url = {http://ieeexplore.ieee.org/iel5/4404892/4404893/04404944.pdf},
    Year = {2007},
    Abstract = {During recent years the experimental SAR (E-SAR) system of the German Aerospace Center (DLR) has continuously been operated to acquire data for different scientific applications in forestry, agriculture and glaciology. In this context, the data where mainly used to develop new scattering models in preparation of future space-borne missions posing increasing accuracy requirements especially for the processing of repeat-pass interferometric data. Also direct model-free methods like differential SAR interferometry for measuring displacements in the order of the wavelength or SAR tomography for real 3D microwave imaging of scattering volumes determined the development of advanced and very accurate motion compensation techniques. This paper first gives an overview of the updates of the E-SAR system performed during the last couple of years and then focusses on the recently developed airborne interferometric processing methods and their applications.},
    Keywords = {SAR Processing, SAR Tomography, Tomography, InSAR, Interferometry, PTA, SATA, Residual Motion Errors, Motion Compensation, DInSAR, Differential InSAR, Differential Interferometry, E-SAR},
    Owner = {ofrey},
    Pdf = {../../../docs/scheiberPratsNanninideMacedoAndresFischerHorn2007.pdf} 
    }
    




25. Philipp Thompson, Matteo Nannini, and Rolf Scheiber. Target separation in SAR image with the MUSIC algorithm. In IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2007., pages 468-471, July 2007. Keyword(s): SAR Processing, SAR Tomography, Tomography, radar imaging, synthetic aperture radar, DLR, E-SAR system, Fourier SAR image, MUSIC, MUSIC algorithm, Spectral Estimation, X-band, corner reflectors, post-processing implementation, super-resolution experiment, target separation, targets geometry.

    Abstract:

    The aim of this work is to exploit the MUSIC algorithm performance in order to enhance target separability in range and azimuth, i.e. achieve point targets separation inside a resolution cell. Simulations have been done in order to plan and check the feasibility of a super-resolution experiment that took place in September 2006 on the test site of Oberpfaffenhofen (Germany). The data set has been acquired with the E-SAR system of the DLR in X-band. The targets to be separated were seven small corner reflectors that have been placed in a way that their response falls in one or, at maximum, two resolution cells of the standard Fourier SAR image. A post-processing implementation of the MUSIC algorithm has been proposed allowing, in the already focused SAR image, to retrieve the targets geometry. Conditions and analysis of the results have been carried out.

    
    

    @InProceedings{thompsonNanniniScheiberTomo2007:Music,
    author = {Thompson, Philipp and Nannini, Matteo and Scheiber, Rolf},
    booktitle = {IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2007.},
    title = {{Target separation in SAR image with the MUSIC algorithm}},
    year = {2007},
    month = {July},
    pages = {468-471},
    abstract = {The aim of this work is to exploit the MUSIC algorithm performance in order to enhance target separability in range and azimuth, i.e. achieve point targets separation inside a resolution cell. Simulations have been done in order to plan and check the feasibility of a super-resolution experiment that took place in September 2006 on the test site of Oberpfaffenhofen (Germany). The data set has been acquired with the E-SAR system of the DLR in X-band. The targets to be separated were seven small corner reflectors that have been placed in a way that their response falls in one or, at maximum, two resolution cells of the standard Fourier SAR image. A post-processing implementation of the MUSIC algorithm has been proposed allowing, in the already focused SAR image, to retrieve the targets geometry. Conditions and analysis of the results have been carried out.},
    doi = {10.1109/IGARSS.2007.4422832},
    keywords = {SAR Processing, SAR Tomography, Tomography, radar imaging, synthetic aperture radar, DLR, E-SAR system, Fourier SAR image, MUSIC, MUSIC algorithm, Spectral Estimation, X-band, corner reflectors, post-processing implementation, super-resolution experiment, target separation, targets geometry},
    owner = {ofrey},
    pdf = {../../../docs/thompsonNanniniScheiberTomo2007.pdf},
    url = {http://ieeexplore.ieee.org/iel5/4422707/4422708/04422832.pdf},
    
    }
    




26. Tan Weixian, Wang Yanping, Hong Wen, Wu Yirong, Li Nanjing, Hu Chufeng, and Zhang Linxi. SAR Three-Dimensional Imaging Experiments with Microwave Anechoic Chamber SAR Data. In Microwave Conference, 2007. APMC 2007. Asia-Pacific, pages 1-4, December 2007.
    

    @InProceedings{Weixian2007,
    Title = {SAR Three-Dimensional Imaging Experiments with Microwave Anechoic Chamber SAR Data},
    Author = {Tan Weixian and Wang Yanping and Hong Wen and Wu Yirong and Li Nanjing and Hu Chufeng and Zhang Linxi},
    Booktitle = {Microwave Conference, 2007. APMC 2007. Asia-Pacific},
    Doi = {10.1109/APMC.2007.4555105},
    Month = dec,
    Pages = {1--4},
    Year = {2007},
    Owner = {ofrey} 
    }
    




27. Andreas Wiesmann, Tazio Strozzi, Charles L. Werner, Urs Wegmuller, and Maurizio Santoro. Microwave remote sensing of alpine snow. In Proc. IEEE Int. Geosci. Remote Sens. Symp., pages 1223-1227, July 2007. Keyword(s): SnowScat, KuScat, microwave measurement, remote sensing by radar, snow, ASSIST, Alpine Safety, Security and Information Services and Technologies, Alpine snow, C-band SAR, CoReH2O mission, SnowScat project, avalanche maps, avalanche warning, flood management, liquid water content, microwave remote sensing, snow coverage, snow structure, Content management, Ecosystems, Information security, Knowledge management, Microwave measurements, Remote sensing, Safety, Satellites, Snow, Space technology, ASSIST, CoReH20, SnowScat, avalanche, snow.

    Abstract:

    In the alpine zone snow is a dominant factor for more than half of the year and has strong influence on the ecosystem and economy. The knowledge of snow coverage, structure, liquid water content etc. is important and useful for many applications ranging from flood management to avalanche warning. Remote sensing from space has good potential to address these needs. Within ASSIST, Alpine Safety, Security and Information services and Technologies, these topics are also of interest. Two snow related products were identified that can be produced on an operational base with the available satellite systems to be ingested into the ASSIST service. Avalanche maps, mapping the contours of avalanches, and snow cover maps, mapping the snow covered area. The produced products are in good agreement with validation data. Unfortunately the current available satellite systems (mainly c-band SAR that is applicable) are not very well suited for snow related applications due to the small influence of the dry snow on the microwave signal at C- band. To overcome this limitation the CoReH2O mission was designed. With its X- and Ku-band system and repeat rates of 3 and 15 days it has high potential for alpine snow applications. Additional microwave signature measurements at these frequencies with standardized and reproducible snow characterization information will be needed for model development and validation. Recent developments allow a more quantitative snow characterizations and will be considered in the SnowScat project in combination with traditional snow characterization methods.

    
    

    @InProceedings{wiesmannEtAlIGARSS2007SnowScat,
    author = {Wiesmann, Andreas and Strozzi, Tazio and Werner, Charles L. and Wegmuller, Urs and Santoro, Maurizio},
    title = {Microwave remote sensing of alpine snow},
    booktitle = {Proc. IEEE Int. Geosci. Remote Sens. Symp.},
    year = {2007},
    pages = {1223-1227},
    month = jul,
    abstract = {In the alpine zone snow is a dominant factor for more than half of the year and has strong influence on the ecosystem and economy. The knowledge of snow coverage, structure, liquid water content etc. is important and useful for many applications ranging from flood management to avalanche warning. Remote sensing from space has good potential to address these needs. Within ASSIST, Alpine Safety, Security and Information services and Technologies, these topics are also of interest. Two snow related products were identified that can be produced on an operational base with the available satellite systems to be ingested into the ASSIST service. Avalanche maps, mapping the contours of avalanches, and snow cover maps, mapping the snow covered area. The produced products are in good agreement with validation data. Unfortunately the current available satellite systems (mainly c-band SAR that is applicable) are not very well suited for snow related applications due to the small influence of the dry snow on the microwave signal at C- band. To overcome this limitation the CoReH2O mission was designed. With its X- and Ku-band system and repeat rates of 3 and 15 days it has high potential for alpine snow applications. Additional microwave signature measurements at these frequencies with standardized and reproducible snow characterization information will be needed for model development and validation. Recent developments allow a more quantitative snow characterizations and will be considered in the SnowScat project in combination with traditional snow characterization methods.},
    doi = {10.1109/IGARSS.2007.4423026},
    file = {:wiesmannEtAlIGARSS2007SnowScat.pdf:PDF},
    keywords = {SnowScat, KuScat, microwave measurement;remote sensing by radar;snow;ASSIST;Alpine Safety, Security and Information Services and Technologies;Alpine snow;C-band SAR;CoReH2O mission;SnowScat project;avalanche maps;avalanche warning;flood management;liquid water content;microwave remote sensing;snow coverage;snow structure;Content management;Ecosystems;Information security;Knowledge management;Microwave measurements;Remote sensing;Safety;Satellites;Snow;Space technology;ASSIST;CoReH20;SnowScat;avalanche;snow},
    
    }
    




28. Tan Wei Xian, Hong Wen, Wang Yan-ping, and Wu Yi-rong. A novel imaging approach for multi-baseline SAR tomography. In Synthetic Aperture Radar, 2007. APSAR 2007. 1st Asian and Pacific Conference on, pages 423-426, November 2007.
    

    @InProceedings{Xian2007,
    Title = {A novel imaging approach for multi-baseline SAR tomography},
    Author = {Tan Wei Xian and Hong Wen and Wang Yan-ping and Wu Yi-rong},
    Booktitle = {Synthetic Aperture Radar, 2007. APSAR 2007. 1st Asian and Pacific Conference on},
    Doi = {10.1109/APSAR.2007.4418641},
    Month = Nov,
    Pages = {423--426},
    Year = {2007},
    Owner = {ofrey},
    Timestamp = {2009.07.01} 
    }
    




29. Evan C. Zaugg and David G. Long. Full motion compensation for LFM-CW synthetic aperture radar. In IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2007., pages 5198-5201, July 2007. Keyword(s): SAR Processing, LFM-CW, LFM-CW SAR, MoComp, motion compensation, CSA, ECS, Chirp Scaling, Extended Chirp Scaling, FSA, Frequency Scaling Algorithm, Range-Doppler Algorithm, synthetic aperture radar, Brigham Young University, muSAR system, LFM-CW signal model, SAR image quality, aircraft, atmospheric turbulence, high-resolution synthetic aperture radar systems, linear frequency-modulated continuous-wave signal, motion correction algorithms, unmanned aerial vehicle, Airborne SAR, geophysical techniques.
    

    @InProceedings{Zaugg2007,
    author = {Zaugg, Evan C. and Long, David G.},
    booktitle = {IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2007.},
    title = {{Full motion compensation for LFM-CW synthetic aperture radar}},
    year = {2007},
    month = jul,
    pages = {5198--5201},
    doi = {10.1109/IGARSS.2007.4424033},
    keywords = {SAR Processing, LFM-CW, LFM-CW SAR, MoComp, motion compensation, CSA, ECS, Chirp Scaling, Extended Chirp Scaling, FSA, Frequency Scaling Algorithm, Range-Doppler Algorithm, synthetic aperture radar, Brigham Young University, muSAR system, LFM-CW signal model, SAR image quality, aircraft, atmospheric turbulence, high-resolution synthetic aperture radar systems, linear frequency-modulated continuous-wave signal, motion correction algorithms, unmanned aerial vehicle, Airborne SAR, geophysical techniques},
    owner = {ofrey},
    
    }
    




30. Howard Zebker, Pius Shankar, and Andy Hooper. InSAR Remote Sensing Over Decorrelating Terrains: Persistent Scattering Methods. In IEEE Radar Conference, pages 717-722, April 2007. Keyword(s): SAR Processing, decorrelation, Temporal Decorrelation, filtering theory, radar interferometry, radar signal processing, remote sensing by radar, synthetic aperture radar, terrain mapping, topography (Earth), vegetation mapping, InSAR remote sensing, San Francisco Bay segments, bare-Earth topography, decorrelation, detection theory, displacement measurement, echoes, filtering algorithms, information theoretic estimation, interferometric synthetic aperture radar, motion mapping, persistent scatterer detection, persistent scattering method, phase unwrapping, radar images, radar signals, spaceborne satellite data, stable true-ground scattering point identification, subtle surface motion mapping, surface deformation, terrain mapping, vegetation mapping, visual geodetic technique, Decorrelation, Displacement measurement, Radar imaging, Radar remote sensing, Radar scattering, Remote sensing, Spaceborne radar, Synthetic aperture radar interferometry, Terrain mapping, Vegetation mapping, InSAR, persistent scattering, radar remote sensing, surface deformation.

    Abstract:

    Interferometric synthetic aperture radar, or InSAR, is a visual geodetic technique permitting detailed mapping of motion over wide areas. InSAR has been limited to regions without much vegetation, which shields the ground from the radar signals and contributes random motions to the observed deformation. The resulting "decorrelation" of the echoes precludes accurate displacement measurements in these areas. Decorrelation also occurs in interferograms with acquisitions separated too far in the sky. Yet certain points, denoted persistent scatterers, in a radar image are stable, do not decorrelate, and form a network of fiducial points that allow measurements in otherwise poor-quality interferograms. We have generalized an algorithm to find networks of stable points in natural terrain, rather than in urban areas, and applied the method to spaceborne satellite data. Using modern information theory to optimize persistent scatterer detection, we can now find many, many more such points than previously possible. We have applied this improved algorithm to the San Francisco Bay segments of the San Andreas and Hayward faults, and in both cases find that a large number of stable points are seen in the vegetated areas that have to date resisted InSAR analysis. Our method of integrating information theoretic estimation and detection theory to all parts of the method, improves the identification, filtering, and phase unwrapping of the observations. Identification of stable true-ground scattering points permits mapping of subtle surface motions and deformations and also of "bare-Earth" topography.

    
    

    @InProceedings{zebkerShankarHooperRadCon2007TempDecorrelation,
    author = {Zebker, Howard and Shankar, Pius and Hooper, Andy},
    title = {{InSAR} Remote Sensing Over Decorrelating Terrains: Persistent Scattering Methods},
    booktitle = {IEEE Radar Conference},
    year = {2007},
    pages = {717-722},
    month = apr,
    abstract = {Interferometric synthetic aperture radar, or InSAR, is a visual geodetic technique permitting detailed mapping of motion over wide areas. InSAR has been limited to regions without much vegetation, which shields the ground from the radar signals and contributes random motions to the observed deformation. The resulting "decorrelation" of the echoes precludes accurate displacement measurements in these areas. Decorrelation also occurs in interferograms with acquisitions separated too far in the sky. Yet certain points, denoted persistent scatterers, in a radar image are stable, do not decorrelate, and form a network of fiducial points that allow measurements in otherwise poor-quality interferograms. We have generalized an algorithm to find networks of stable points in natural terrain, rather than in urban areas, and applied the method to spaceborne satellite data. Using modern information theory to optimize persistent scatterer detection, we can now find many, many more such points than previously possible. We have applied this improved algorithm to the San Francisco Bay segments of the San Andreas and Hayward faults, and in both cases find that a large number of stable points are seen in the vegetated areas that have to date resisted InSAR analysis. Our method of integrating information theoretic estimation and detection theory to all parts of the method, improves the identification, filtering, and phase unwrapping of the observations. Identification of stable true-ground scattering points permits mapping of subtle surface motions and deformations and also of "bare-Earth" topography.},
    doi = {10.1109/RADAR.2007.374307},
    file = {:zebkerShankarHooperRadCon2007TempDecorrelation.pdf:PDF},
    issn = {1097-5659},
    keywords = {SAR Processing, decorrelation; Temporal Decorrelation, filtering theory;radar interferometry;radar signal processing;remote sensing by radar;synthetic aperture radar;terrain mapping;topography (Earth);vegetation mapping;InSAR remote sensing;San Francisco Bay segments;bare-Earth topography;decorrelation;detection theory;displacement measurement;echoes;filtering algorithms;information theoretic estimation;interferometric synthetic aperture radar;motion mapping;persistent scatterer detection;persistent scattering method;phase unwrapping;radar images;radar signals;spaceborne satellite data;stable true-ground scattering point identification;subtle surface motion mapping;surface deformation;terrain mapping;vegetation mapping;visual geodetic technique;Decorrelation;Displacement measurement;Radar imaging;Radar remote sensing;Radar scattering;Remote sensing;Spaceborne radar;Synthetic aperture radar interferometry;Terrain mapping;Vegetation mapping;InSAR;persistent scattering;radar remote sensing;surface deformation},
    pdf = {../../../docs/zebkerShankarHooperRadCon2007TempDecorrelation.pdf},
    
    }
    

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