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Evaluation of Terrasar-X observations for wetland INSAR application / S.H. Hong in IEEE Transactions on geoscience and remote sensing, vol 48 n° 2 (February 2010)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 48 n° 2 (February 2010) . - pp 864 - 873 Titre : Evaluation of Terrasar-X observations for wetland INSAR application Type de document : Article/Communication Auteurs : S.H. Hong, Auteur ; S. Wdowinski, Auteur ; S.W. Kim, Auteur Année de publication : 2010 Article en page(s) : pp 864 - 873 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] bande X [Termes IGN] cohérence des données [Termes IGN] Floride (Etats-Unis) [Termes IGN] image radar moirée [Termes IGN] image TerraSAR-X [Termes IGN] interféromètrie par radar à antenne synthétique [Termes IGN] marais [Termes IGN] polarimétrie radar Résumé : (Auteur) This paper assesses the potential of using spaceborne X-band synthetic aperture radar (SAR) data for monitoring water-level changes over wetlands. Our analysis is based on three sets of TerraSAR-X (TSX) observations acquired over South Florida's Everglades wetlands during an eight-month period in 2008. The first set was acquired in single HH polarization stripmap mode over our northern study area, consisting of managed wetlands and urban environments. The second set was acquired in dual-polarization stripmap mode over the western half of the same area, consisting mostly of managed wetlands. The third set was also acquired with dual-polarization stripmap mode over our southern study area, consisting of natural flow freshand salt-water wetlands in the southern Everglades. The first data set was used for a proof-of-concept study to verify that X-band data can generate coherent interferograms in wetland areas. Interferometric processing of this data set shows a high level of coherence (> 0.35) over both wetland and urban regions, maintaining interferometric phase in all three interferograms spanning 11 days. Surprisingly, phase is maintained over some of the wetlands even for interferograms spanning 33 days. The other two data sets were used to evaluate interferometric coherence of all four polarization modes and to determine dominant scattering mechanism in each wetland environment. Our results show high coherence values (> 0.4) in all polarization modes, with highest values in HH, then VV, and lowest in HV or VH. Interferograms calculated from multipolarization data show very similar fringe patterns regardless of the polarization type, suggesting that the phase information in all polarization data reflects water-level changes in wetlands and that volume scattering may be less important than commonly believed. We also used the two multipolarization data sets to conduct the Pauli decomposition, finding a strong dependence of scattering mechanism on vegetation type. The high interferometric coherence level of all polarization data suggests that a significant part of the X-band scattered signal interacts with lower sections of the vegetation (trunks and branches), because scattering from wind-affected canopies cannot support such a high coherence level. The high spatial resolution of TSX, combined with its 11-day repeat orbit, makes this X-band sensor surprisingly suitable for wetland interferometric SAR applications. Copyright IEEE Numéro de notice : A2010-041 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2009.2026895 Date de publication en ligne : 28/08/2009 En ligne : https://doi.org/10.1109/TGRS.2009.2026895 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30237 [article]

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Extraction of ground control points (GCPs) from synthetic aperture radar images and SRTM DEM / S.H. Hong in International Journal of Remote Sensing IJRS, vol 27 n°18 - 19 - 20 (October 2006)  

Public [article]  inInternational Journal of Remote Sensing IJRS > vol 27 n°18 - 19 - 20 (October 2006) . - pp 3813 - 3829 Titre : Extraction of ground control points (GCPs) from synthetic aperture radar images and SRTM DEM Type de document : Article/Communication Auteurs : S.H. Hong, Auteur ; Hyung-Sup Jung, Auteur ; J.S. Won, Auteur Année de publication : 2006 Article en page(s) : pp 3813 - 3829 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] écart type [Termes IGN] extraction [Termes IGN] image ERS-SAR [Termes IGN] image IRS [Termes IGN] MNS SRTM [Termes IGN] modèle numérique de surface [Termes IGN] point d'appui [Termes IGN] radargrammétrie Résumé : (Auteur) Qualified ground control points (GCPs) are crucial in the geolocation of a remotely sensed image. If a region has no published map, the geographical coordinates of GCPs must be obtained indirectly. Although these can be re-constructed from a synthetic aperture radar (SAR) image using sensor position and velocity, this conventional method does not provide accurate GCPs owing to the variable elevations of actual topography. We propose an inverse geolocation method for GCPs by SAR simulation. This improves the accuracy of extracted GCPs by accommodating topographic effects, and requires a high-resolution digital elevation model (DEM) and SAR with precise orbit data. The errors in the northing derive mainly from the imaging pulse time, and were improved by applying an azimuth time correction. In this study ERS SAR data with precise Delft orbit and shuttle radar topography mission (SRTM) DEM were used. Mean values for the planimetric distance error in the GCPs were 4.1 and 5.4 m with standard deviations of 10.6 and 16.9 m in northing and easting, respectively. The obtained GCPs were applied to an IRS image for geo-rectification, and the result was mean image positional errors of 3.6 and 2.7 m with standard deviations of 8.4 and 15.4 m in northing and easting, respectively. The root mean square errors are 9.0 and 15.3 m in northing and easting, respectively. Copyright Taylor & Francis Numéro de notice : A2006-457 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01431160600658115 En ligne : https://doi.org/10.1080/01431160600658115 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28181 [article]

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