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The TropiSAR airborne campaign in French Guiana : objectives, description, and observed temporal behavior of the backscatter signal / P. Dubois-Fernandez in IEEE Transactions on geoscience and remote sensing, vol 50 n° 8 (August 2012)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 50 n° 8 (August 2012) . - pp 3228 - 3241 Titre : The TropiSAR airborne campaign in French Guiana : objectives, description, and observed temporal behavior of the backscatter signal Type de document : Article/Communication Auteurs : P. Dubois-Fernandez, Auteur ; Thuy Le Toan, Auteur ; S. Daniel, Auteur ; et al., Auteur Année de publication : 2012 Article en page(s) : pp 3228 - 3241 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] bande P [Termes IGN] biomasse [Termes IGN] forêt tropicale [Termes IGN] Guyane (département français) [Termes IGN] image aérienne [Termes IGN] image radar moirée [Termes IGN] image SETHI [Termes IGN] polarisation croisée [Termes IGN] qualité radiométrique (image) Résumé : (Auteur) The TropiSAR campaign has been conducted in August 2009 in French Guiana with the ONERA airborne radar system SETHI. The main objective of this campaign was to collect data to support the Phase A of the 7th Earth Explorer candidate mission, BIOMASS. Several specific questions needed to be addressed to consolidate the mission concept following the Phase 0 studies, and the data collection strategy was constructed accordingly. More specifically, a tropical forest data set was required in order to provide test data for the evaluation of the foreseen inversion algorithms and data products. The paper provides a description of the resulting data set which is now available through the European Space Agency website under the airborne campaign link. First results from the TropiSAR database analysis are presented with two in-depth analyses about both the temporal radiometric variation and temporal coherence at P-band. The temporal variations of the backscatter values are less than 0.5 dB throughout the campaign, and the coherence values are observed to stay high even after 22 days. These results are essential for the BIOMASS mission. The observed temporal stability of the backscatter is a good indicator of the expected robustness of the biomass estimation in tropical forests, from cross-polarized backscatter values as regarding environmental changes such as soil moisture. The high temporal coherence observed after a 22-day period is a prerequisite for SAR Polarimetric Interferometry and Tomographic applications in a single satellite configuration. The conclusion then summarizes the paper and identifies the next steps in the analysis. Numéro de notice : A2012-388 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2011.2178246 Date de publication en ligne : 18/01/2012 En ligne : https://doi.org/10.1109/TGRS.2011.2178246 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31834 [article]

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The compact polarimetry alternative for spaceborne SAR at low frequency / P. Dubois-Fernandez in IEEE Transactions on geoscience and remote sensing, vol 46 n° 10 Tome 2 (October 2008)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 46 n° 10 Tome 2 (October 2008) . - pp 3208 - 3222 Titre : The compact polarimetry alternative for spaceborne SAR at low frequency Type de document : Article/Communication Auteurs : P. Dubois-Fernandez, Auteur ; J.C. Souyris, Auteur ; S. Angelliaume, Auteur ; et al., Auteur Année de publication : 2008 Conférence : IGARSS 2007, International Geoscience And Remote Sensing Symposium, sensing and understanding our planet 23/07/2007 27/07/2007 Barcelone Espagne Proceedings IEEE Article en page(s) : pp 3208 - 3222 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] bande L [Termes IGN] données polarimétriques [Termes IGN] forêt tempérée [Termes IGN] image ALOS-PALSAR [Termes IGN] interféromètrie par radar à antenne synthétique [Termes IGN] Landes (40) [Termes IGN] Pinus pinaster [Termes IGN] polarimétrie radar Résumé : (Auteur) In spaceborne synthetic aperture radar (SAR), a single-polarization on-transmit offers twice the swath width compared to full polarization. This is linked to SAR system design issues, and, without getting into the technical details deserving by themselves a full paper, we can just mention the swath characteristics of ALOS PALSAR (the Advanced Land Observing Satellite, Phased Array L-Band Synthetic Aperture Radar), reducing from 70 km for the dual-pol mode to 30 km for the full polarization mode. The reduced coverage in the full polarization mode has a harmful impact on the revisit time, which is always a major drive for the Earth-observing community. The options chosen up to now for dual-pol system designs (or single-polarization on-transmit) rely on a linear polarization on-transmit [either horizontal (H) or vertical (V)], with two orthogonal polarizations on-receive. Souyris and Raney in earlier papers proposed more pertinent alternatives for the selection of the transmit polarization leading to a better characterization of the scattering mechanisms. In this paper, the analysis is pursued in more depth by including the effect of the ionosphere on the wave propagation and extending the applications to polarimetric interferometry SAR (PolInSAR). A compact mode is developed where the transmit polarization is circular, whereas the only constraint on the two receiving polarizations is independence. Indeed, the choice of the polarizations of the two receive channels does not matter, as any polarization on-receive can be synthesized from these two measurements. This is, however, not the case for the unique transmit polarization. At a low frequency, where the ionosphere has a significant effect, the circular transmit polarization is the only sensible option, as it provides an effective constant polarization as seen by the scattering surface. This is an essential condition for a meaningful multitemporal analysis. Both the polarimetric SAR applications and the PolInSAR applications in the context of this compact polarimetry (CP) mode are explored. A pseudocovariance matrix can be reconstructed following Souyris' proposed approach for distributed targets and is shown to be very similar to the full polarimetric (FP) covariance matrix. The reconstruction of the cross-polarized Sigma0 is shown to be reliable and to have very low sensitivity to Faraday rotation. A PolInSAR vegetation height inversion for P-band is presented and applied to the CP data with a level of performance that is similar to the one derived from FP (a 1.2-m root-mean-square height error on the ONERA Airborne radar (RAMSES) data over the Landes Forest). A procedure is developed to correct for the ionospheric effects for the PolInSAR acquisition in the FP or CP mode and is assessed on the data simulated from an airborne acquisition. The results demonstrate that the technique is efficient and robust. The calibration of CP data is identified as an important challenge to be solved, and some clues are provided to address the problem. Numéro de notice : A2008-529 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2008.919143 En ligne : https://doi.org/10.1109/TGRS.2008.919143 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29599 [article]

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Discrimination potential of X-band polarimetric SAR data / Nicolas Baghdadi in International Journal of Remote Sensing IJRS, vol 25 n° 22 (November 2004)  

Public [article]  inInternational Journal of Remote Sensing IJRS > vol 25 n° 22 (November 2004) . - pp 4933 - 4943 Titre : Discrimination potential of X-band polarimetric SAR data Type de document : Article/Communication Auteurs : Nicolas Baghdadi, Auteur ; N. Holah, Auteur ; P. Dubois-Fernandez, Auteur ; L. Prevot, Auteur ; et al., Auteur Année de publication : 2004 Article en page(s) : pp 4933 - 4943 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] analyse discriminante [Termes IGN] anisotropie [Termes IGN] Avignon [Termes IGN] bande X [Termes IGN] données polarimétriques [Termes IGN] image radar moirée [Termes IGN] image RAMSES [Termes IGN] Radar Aéroporté Multi-Spectral d'Etude des Signatures [Termes IGN] sol nu Résumé : (Auteur) In anticipation of X-band polarimetric Synthetic Aperture Radar (SAR) data from future sensors, we investigated the potential of X-band fully polarimetric data for discriminating between the principal classes present in a study site near Avignon, France. Decomposition and analysis techniques have been applied to a dataset acquired by the ONERA airborne RAMSES (Radar Aéroporté Multi-Spectral d'Etude des Signatures) SAR. Results show that X-band provides some discrimination capability. The polarimetric parameters, entropy and Ü-angle, show clearly that these signature classes are grouped into five clusters corresponding to physical scattering characteristics. The introduction of the anisotropy parameter does not increase our ability to distinguish between different classes whose clusters are in the same entropy/Ü-angle zone. The correlation observed between the radar signal and the surface roughness over bare soils is very low. Numéro de notice : A2004-488 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01431160412231269652 En ligne : https://doi.org/10.1080/01431160412231269652 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27006 [article]

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