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Extracting precise and affordable DEMs despite of the clouds. Ajax: the joining of radar and optical strengths / Laurent Cunin (2012)  

Public Titre : Extracting precise and affordable DEMs despite of the clouds. Ajax: the joining of radar and optical strengths Type de document : Article/Communication Auteurs : Laurent Cunin , Auteur ; Philippe Nonin, Auteur ; Juergen Janoth, Auteur ; Marc Bernard, Auteur Editeur : International Society for Photogrammetry and Remote Sensing ISPRS Année de publication : 2012 Collection : International Archives of Photogrammetry, Remote Sensing and Spatial Information Sciences, ISSN 1682-1750 num. 39-B4 Conférence : ISPRS 2012, Commission 4, 22th international congress 25/08/2012 01/09/2012 Melbourne Australie OA ISPRS Archives Commission 4 Importance : pp 271 - 274 Format : 21 x 30 cm Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image mixte [Termes IGN] Colombie [Termes IGN] Congo [Termes IGN] Elevation30/Reference3D [Termes IGN] image SPOT-HRS [Termes IGN] image TerraSAR-X [Termes IGN] modèle numérique de surface [Termes IGN] nuage [Termes IGN] Référence-3D Résumé : (auteur) On the one hand, onboard SPOT 5, the HRS instrument systematically collects stereopairs around the Globe since 2002. Each stereopair can encompass an area up to 600 km x 120 km within a single pass (i.e. 72 000 km² stereoscopic strips). Covering now more than 120 millions sq.km of the Earth landmasses, SPOT 5 stereoscopic imagery has become one of main satellite data sources for accurate DEM extraction, at least where the cloud coverage leaves a chance to do so ! On the other hand, the TerraSAR-X satellite, launched in June 2007, is able to collect radar data through the clouds in several modes. An approach to extract height information by radargrammetry was developed, and the commercial distribution of Digital Elevation Models based on TerraSAR-X StripMap and SpotLight Modes (resp. 3m and 1m resolution) has started in 2010. To improve the overall height accuracy of the DEM, acquisitions from both orbit directions are utilised, each point on the ground being thus imaged at least 4 times by TerraSAR-X. Since 2002, Spot Image and French National Cartographic Institute (IGN) are building a worldwide database called Elevation30/Reference3D™, which includes a Digital Elevation Model at 1-arc-second resolution (DTED level 2) extracted from HRS stereopairs. To answer the wide demand of precise DEMs over Tropical and Northern areas, frequently covered by clouds, a study was performed to integrate StripMap radargrammetric TerraSAR-X data into the Reference3D process, and two prototype products were issued, over Colombia and Congo areas. During this experiment, efforts have been made to stick to technical steps that could be integrated within a standardized production process, in order to keep offering affordable prices while maintaining a high standard of horizontal and vertical accuracy. The DEMs extracted from TerraSAR-X and HRS proved extremely consistent with each other, showing a mean difference of 0.80m. This allows to propose a unified Elevation30 product to the users, with a guaranteed accuracy materialized into the product through a dedicated vertical Accuracy Commitment Mask. Numéro de notice : C2012-018 Affiliation des auteurs : IGN+Ext (2012-2019) Thématique : IMAGERIE Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : 10.5194/isprsarchives-XXXIX-B4-271-2012 Date de publication en ligne : 31/07/2012 En ligne : http://dx.doi.org/10.5194/isprsarchives-XXXIX-B4-271-2012 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94283