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Persistent scatterers at building facades – Evaluation of appearance and localization accuracy / Stefan Gernhardt in ISPRS Journal of photogrammetry and remote sensing, vol 100 (February 2015)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 100 (February 2015) . - pp 92 - 105 Titre : Persistent scatterers at building facades – Evaluation of appearance and localization accuracy Type de document : Article/Communication Auteurs : Stefan Gernhardt, Auteur ; Stefan Auer, Auteur ; Konrad Eder, Auteur Année de publication : 2015 Article en page(s) : pp 92 - 105 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] coin réflecteur [Termes IGN] estimation de position [Termes IGN] façade [Termes IGN] image optique [Termes IGN] image radar moirée [Termes IGN] modèle 3D de l'espace urbain [Termes IGN] modélisation 3D [Termes IGN] Munich [Termes IGN] photogrammétrie architecturale [Termes IGN] photogrammétrie terrestre Résumé : (auteur) Thanks to the high resolution of modern SAR satellites many persistent scatterers (PS) appear at single buildings. Approximately half of them represent building facades. These groups of points often show regular patterns in SAR images that can be related to repeating structure elements on the facades. Hence, individual buildings can now be monitored over time, either based on amplitude (for change detection) or phase information (using interferometric methods). However, patterns of point signatures are often disrupted or disappear when the imaging geometry is slightly changed. In addition, the localization accuracy of estimated and geocoded natural PS is not known, yet. The investigation at hand provides a detailed analysis of PS patterns based on reference data obtained from a photogrammetric survey and terrestrial measurements. The processing of the optical images allows creating a detailed 3D model of the respective facade, which represents the geometrical object information for SAR simulation. The terrestrial measurements allow relating the 3D model to its true position in a world coordinate system like UTM (Universal Transverse Mercator), which is necessary for assessing the localization accuracy of the signatures. From the simulation results the appearance of the point patterns of natural PS in high resolution SAR data can be better understood. Moreover, the localization accuracy and the precision for these points can be derived for the first time. The approach and findings for two case studies in Munich are described in detail in this paper. Numéro de notice : A2015-056 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2014.05.014 En ligne : https://doi.org/10.1016/j.isprsjprs.2014.05.014 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75300 [article]

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081-2015021	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Deformation monitoring of single buildings using meter-resolution SAR data in PSI / Stefan Gernhardt in ISPRS Journal of photogrammetry and remote sensing, vol 73 (September 2012)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 73 (September 2012) . - pp 68 - 79 Titre : Deformation monitoring of single buildings using meter-resolution SAR data in PSI Type de document : Article/Communication Auteurs : Stefan Gernhardt, Auteur ; R. Bamler, Auteur Année de publication : 2012 Article en page(s) : pp 68 - 79 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] analyse diachronique [Termes IGN] déformation d'édifice [Termes IGN] semis de points Résumé : (Auteur) In this paper the feasibility to monitor the shape and deformation of single buildings from space is investigated. The methodology is based on a fusion of persistent scatterer (PS) point clouds obtained from several stacks of meter-resolution synthetic aperture radar (SAR) data. This kind of high resolution imagery as well as accurate orbit information is available from, e.g., TerraSAR-X. The stacks are processed individually applying persistent scatterer interferometry (PSI), which provides deformation and height estimates for the PS. However, the geocoded PS point clouds cannot be simply merged in one common coordinate system, like UTM, by reason of residual offsets with respect to their final true positions. These deviations originate from the height uncertainty of the reference point, which has to be chosen during PSI processing of each stack. The presented methodology allows for a fusion of several PS point clouds, i.e., the correct reference point heights can be recovered. The algorithm is based on a point cloud matching procedure that consists of a determination of appropriate point correspondences and a minimization of the distances between all selected pairs of points in a least-squares sense. In addition, the reconstruction of the original motion vector from the deformation measurements in line of sight provided by PSI is desirable. The availability of separated motion components in vertical and horizontal directions greatly enhances the insights into deformation events at buildings and ground. To this end, the fused point clouds are used for a decomposition of motion components. By reason of the limited sensitivity of ascending and descending stacks of TerraSAR-X to deformation in north-southern directions the reconstruction of motion vector components is restricted to components in west-eastern and vertical directions. The latter are estimated in a least-squares adjustment including all PS within a spatially limited area. Deformation estimates of stacks from ascending and descending tracks must be included in order to separate motion components. The latter cannot be determined precisely from a combination of solely equal heading tracks, as the line of sight does not differ enough. Finally, deformation maps of the urban area are available that separately show seasonal and linear deformation in horizontal as well as vertical directions. These maps comprise important information on subsidence or uplift as well as structural stress at buildings due to thermal dilation. As a result of the presented methodology (and for the first time) sufficient and precise motion estimates are available for a detailed monitoring of single objects using meter-resolution SAR data in PSI. Several examples are discussed using the results of motion component estimation based on the fusion of four data stacks evaluated by PSI. Numéro de notice : A2012-545 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2012.06.009 En ligne : https://doi.org/10.1016/j.isprsjprs.2012.06.009 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31991 [article]

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