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Ionospheric artifacts in simultaneous L-band InSAR and GPS observations / J. Chen in IEEE Transactions on geoscience and remote sensing, vol 50 n° 4 (April 2012)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 50 n° 4 (April 2012) . - pp 11227 - 1239 Titre : Ionospheric artifacts in simultaneous L-band InSAR and GPS observations Type de document : Article/Communication Auteurs : J. Chen, Auteur ; H. Zebker, Auteur Année de publication : 2012 Article en page(s) : pp 11227 - 1239 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] artefact [Termes IGN] bande L [Termes IGN] image ALOS-PALSAR [Termes IGN] image radar moirée [Termes IGN] interféromètrie par radar à antenne synthétique [Termes IGN] propagation ionosphérique [Termes IGN] teneur totale en électrons Résumé : (Auteur) Phase artifacts in interferometric synthetic aperture radar (InSAR) images frequently degrade the interpretability of the phase and correlation signatures of terrain. Often, these distortions are attributed to spatially variable ionospheric propagation delays at two different SAR acquisition times. We present here L-band InSAR data from Iceland, California, and Hawaii. The California and Hawaii interferograms show no significant ionospheric artifacts, while the Iceland interferogram shows a maximum misregistration of three pixels in the azimuth direction, which leads to severe phase decorrelation artifacts in the InSAR image. We relate the misregistration of complex pixels seen in the interferograms to the gradient of the ionospheric total electron content (TEC) observed by global positioning system (GPS) data and confirm that indeed the phase artifacts in the Iceland interferogram are due to dispersive ionospheric propagation rather than other decorrelation factors such as neutral atmospheric delays. We develop a method to measure the spatial TEC variation at synthetic aperture length scales using dual-frequency GPS carrier phase data. We solve for the GPS data ambiguities using a low-resolution ionosphere reference derived from either available ionospheric observations or the GPS carrier phase data themselves. GPS observations show directly the level of ionospheric variability, and the spatial TEC gradient as observed by GPS predicts the misregistration of complex pixels in interferograms in all three areas. This confirmation of the cause of the image artifacts suggests that they can be routinely corrected from the InSAR data alone, provided that the sensor measures the change in TEC along the radar swath. Numéro de notice : A2012-136 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2011.2164805 Date de publication en ligne : 06/10/2011 En ligne : https://doi.org/10.1109/TGRS.2011.2164805 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31584 [article]

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065-2012041	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Geodetically accurate InSAR data processor / H. Zebker in IEEE Transactions on geoscience and remote sensing, vol 48 n° 12 (December 2010)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 48 n° 12 (December 2010) . - pp 4309 - 4321 Titre : Geodetically accurate InSAR data processor Type de document : Article/Communication Auteurs : H. Zebker, Auteur ; S. Hensley, Auteur ; P. Shanker, Auteur ; C. Wortham, Auteur Année de publication : 2010 Article en page(s) : pp 4309 - 4321 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] coin réflecteur [Termes IGN] compensation [Termes IGN] image ALOS-PALSAR [Termes IGN] image radar moirée [Termes IGN] interféromètrie par radar à antenne synthétique [Termes IGN] précision du positionnement [Termes IGN] superposition d'images Résumé : (Auteur) We present a new interferometric synthetic aperture radar (InSAR) processing approach that capitalizes on the precise orbit tracking that is available with modern radar satellites. Our method uses an accurate orbit information along with motion-compensation techniques to propagate the radar echoes to positions along a noninertial virtual orbit frame in which the location and focusing equations are particularly simple, so that images are focused without requiring autofocus techniques and are computed efficiently. Motion compensation requires two additional focus correction phase terms that are implemented in the frequency domain. If the images from an interferometric pair or stack are all computed along the same reference orbit, flat-Earth topographic correction is not needed, and image coregistration is simplified, obviating many difficulties that are often encountered in InSAR processing. We process several data sets collected by the ALOS PALSAR instrument and find that the geodetic accuracy of the radar images is 10-20 m, with up to 20 m of additional image distortion needed to align 100 km x 100 km scenes with reference digital elevation models. We validated the accuracy by using both known radar corner reflector locations and by the registration of the interferograms with digital maps. The topography-corrected interferograms are free from all geometric phase terms, and they clearly show the geophysical observables of crustal deformation, atmospheric phase, and ionospheric phase. Numéro de notice : A2010-513 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2010.2051333 Date de publication en ligne : 15/07/2010 En ligne : https://doi.org/10.1109/TGRS.2010.2051333 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30705 [article]

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Code-barres	Cote	Support	Localisation	Section	Disponibilité
065-2010121	RAB	Revue	Centre de documentation	En réserve L003	Disponible

ScanSAR-to-Stripmap mode interferometry processing using ENVISAT-ASAR Data / A.B. Ortiz in IEEE Transactions on geoscience and remote sensing, vol 45 n° 11 Tome 1 (November 2007)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 45 n° 11 Tome 1 (November 2007) . - pp 3468 - 3480 Titre : ScanSAR-to-Stripmap mode interferometry processing using ENVISAT-ASAR Data Type de document : Article/Communication Auteurs : A.B. Ortiz, Auteur ; H. Zebker, Auteur Année de publication : 2007 Article en page(s) : pp 3468 - 3480 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] analyse diachronique [Termes IGN] éruption volcanique [Termes IGN] Hawaii (Etats-Unis) [Termes IGN] image Envisat-ASAR [Termes IGN] image radar moirée [Termes IGN] interféromètrie par radar à antenne synthétique [Termes IGN] séisme [Termes IGN] transformation en Z Résumé : (Auteur) Interferometric synthetic aperture radar (InSAR) images of geophysical events such as preeruptive volcano deformation or interseismic strain accumulation are often limited by phase distortions from the superimposed atmospheric signature. Additionally, the approximate monthly repeat cycle of many radar satellites cannot accurately capture rapidly time-varying processes. The Scanning Synthetic Aperture Radar (ScanSAR) mode of the ENVISAT/ASAR instrument permits more frequent revisits of a given area, potentially overcoming both of these limitations. In particular, stripmap mode-to-ScanSAR images provide a denser time series of interferograms than is possible with conventional stripmap-to-stripmap mode InSAR. We present images of ENVISAT/ASAR data acquired over Hawaii in which data acquired roughly weekly in ScanSAR mode are combined with ENVISAT/ASAR conventional stripmap mode data to form interferograms at a much denser temporal spacing. The burst nature of ScanSAR data requires a new processing method to form the interferograms. We use traditional matched filtering for the range compression. For the azimuth processing, we compute the stripmap mode data on the ScanSAR sampling grid using a variation, consisting of different reference functions, of Lanari's modified SPECAN algorithm that is itself an adaptation of the chirp z -transform to readjust the azimuth pulse spacing. The resulting interferograms faithfully reflect the phase of conventional interferograms, but exhibit fewer looks and coarser resolution than those produced by fully stripmap mode data. For many problems, temporal density of the deformation observations is paramount, and the time series analysis and temporal averaging that were made possible using ScanSAR interferograms far out-weigh the loss in looks and resolution. Copyright IEEE Numéro de notice : A2007-504 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2007.895970 En ligne : https://doi.org/10.1109/TGRS.2007.895970 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28867 [article]

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Radar stereo- and interferometry-derived digital elevation models: comparison and combination using Radarsat and ERS-2 imagery / M. Gelautz in International Journal of Remote Sensing IJRS, vol 24 n° 24 (December 2003)  

Public [article]  inInternational Journal of Remote Sensing IJRS > vol 24 n° 24 (December 2003) . - pp 5243 - 5264 Titre : Radar stereo- and interferometry-derived digital elevation models: comparison and combination using Radarsat and ERS-2 imagery Type de document : Article/Communication Auteurs : M. Gelautz, Auteur ; P. Paillou, Auteur ; C.W. Chen, Auteur ; H. Zebker, Auteur Année de publication : 2003 Article en page(s) : pp 5243 - 5264 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] acquisition d'images [Termes IGN] analyse comparative [Termes IGN] histogramme [Termes IGN] image ERS-SAR [Termes IGN] image Radarsat [Termes IGN] interféromètrie par radar à antenne synthétique [Termes IGN] modèle numérique de surface [Termes IGN] modèle stéréoscopique [Termes IGN] pente Résumé : (Auteur) In this experiment, we derive and compare radar stereo and interferometric digital elevation models (DEMs) of a study site in Djibouti, East Africa. A Radarsat stereo pair, as well as Radarsat and ERS-2 interferometric data, comprise the test images. The primary objective of the study was to analyse and compare the results obtained by the two techniques and explore possible synergisms between them. We find that in regions of high coherence, the DEMs produced by interferometry are of much better quality than the stereo result. However, the corresponding error histograms also show some pronounced errors due to decorrelation and phase-unwrapping problems on forested mountain slopes. On the other hand, the more robust stereo reconstruction, with an error standard deviation of 45m, is able to capture the general terrain shape, although finer ' surface details are lost. In the second part of our experiment, we demonstrate that merging the stereoscopic and interferometric DEMs by applying a user-defined weighting function to a filtered coherence map can significantly improve the accuracy of the computed elevation maps Numéro de notice : A2003-343 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/0143116031000115139 En ligne : https://doi.org/10.1080/0143116031000115139 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22638 [article]

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Code-barres	Cote	Support	Localisation	Section	Disponibilité
080-03241	RAB	Revue	Centre de documentation	En réserve L003	Exclu du prêt