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Auteur Adrian Schubert |
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High-precision positioning of radar scatterers / Prabu Dheenathayalan in Journal of geodesy, vol 90 n° 5 (May 2016)
[article]
Titre : High-precision positioning of radar scatterers Type de document : Article/Communication Auteurs : Prabu Dheenathayalan, Auteur ; David Small, Auteur ; Adrian Schubert, Auteur ; Ramon F. Hanssen, Auteur Année de publication : 2016 Article en page(s) : pp 403 – 422 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] diffusomètre
[Termes IGN] données localisées 3D
[Termes IGN] ellipsoïde (géodésie)
[Termes IGN] image TerraSAR-X
[Termes IGN] interféromètrie par radar à antenne synthétique
[Termes IGN] matrice de covariance
[Termes IGN] précision du positionnement
[Termes IGN] série temporelle
[Termes IGN] télédétection spatialeRésumé : (auteur) Remote sensing radar satellites cover wide areas and provide spatially dense measurements, with millions of scatterers. Knowledge of the precise position of each radar scatterer is essential to identify the corresponding object and interpret the estimated deformation. The absolute position accuracy of synthetic aperture radar (SAR) scatterers in a 2D radar coordinate system, after compensating for atmosphere and tidal effects, is in the order of centimeters for TerraSAR-X (TSX) spotlight images. However, the absolute positioning in 3D and its quality description are not well known. Here, we exploit time-series interferometric SAR to enhance the positioning capability in three dimensions. The 3D positioning precision is parameterized by a variance–covariance matrix and visualized as an error ellipsoid centered at the estimated position. The intersection of the error ellipsoid with objects in the field is exploited to link radar scatterers to real-world objects. We demonstrate the estimation of scatterer position and its quality using 20 months of TSX stripmap acquisitions over Delft, the Netherlands. Using trihedral corner reflectors (CR) for validation, the accuracy of absolute positioning in 2D is about 7 cm. In 3D, an absolute accuracy of up to ∼66 cm is realized, with a cigar-shaped error ellipsoid having centimeter precision in azimuth and range dimensions, and elongated in cross-range dimension with a precision in the order of meters (the ratio of the ellipsoid axis lengths is 1/3/213, respectively). The CR absolute 3D position, along with the associated error ellipsoid, is found to be accurate and agree with the ground truth position at a 99% confidence level. For other non-CR coherent scatterers, the error ellipsoid concept is validated using 3D building models. In both cases, the error ellipsoid not only serves as a quality descriptor, but can also help to associate radar scatterers to real-world objects. Numéro de notice : A2016-268 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0883-4 En ligne : https://doi.org/10.1007/s00190-015-0883-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80808
in Journal of geodesy > vol 90 n° 5 (May 2016) . - pp 403 – 422[article]Glacier surface velocity estimation using repeat TerraSAR-X images: Wavelet- vs. correlation-based image matching / Adrian Schubert in ISPRS Journal of photogrammetry and remote sensing, vol 82 (August 2013)
[article]
Titre : Glacier surface velocity estimation using repeat TerraSAR-X images: Wavelet- vs. correlation-based image matching Type de document : Article/Communication Auteurs : Adrian Schubert, Auteur ; Annina Faes, Auteur ; Andreas Kääb, Auteur ; Erich Meier, Auteur Année de publication : 2013 Article en page(s) : pp 49 - 62 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications
[Termes IGN] analyse comparative
[Termes IGN] appariement d'images
[Termes IGN] corrélation
[Termes IGN] glacier
[Termes IGN] image radar moirée
[Termes IGN] image TerraSAR-X
[Termes IGN] ondelette
[Termes IGN] Suisse
[Termes IGN] surveillance écologique
[Termes IGN] vitesseRésumé : (Auteur) For the observation and monitoring of glacier surface velocity (GSV), remote sensing is an increasingly suitable tool thanks to the high temporal and spatial resolution of the data. Radar sensors have the specific advantage over optical sensors of being nearly weather and time-independent. Two image pairs separated by 11 days, acquired with the high-resolution spotlight (HS) and stripmap (SM) modes of the German sensor TerraSAR-X, were used to estimate GSV over Switzerland’s Aletsch Glacier. The SM mode covers larger ground swaths, making it more suitable for glacier-wide observations, while the HS images cover less area but offer the highest-possible spatial resolution, approximately 1x1 m on the ground. The images were acquired during the summer to maximise feature visibility by minimal snow cover. GSV estimation was performed using two methods, the comparison of which was a major goal of this study: traditional cross-correlation optimisation and a dense image matching algorithm based on complex wavelet decomposition. Each method was found to have unique advantages and disadvantages, but it was concluded that for GSV monitoring, cross-correlation is probably preferable to the wavelet-based approach. While it generates fewer estimates per unit area, this is not necessarily a critical requirement for all glaciological applications, and the method requires less initial “tuning” (calibration) than the wavelet algorithm, making it a slightly better tool in operational contexts. Also, the use of the highest-resolution spotlight datasets is recommended over stripmap mode images when large-area coverage is less critical. The comparative lack of visible features at the resolution of the stripmap images made reliable GSV estimation difficult, with the exception of several small areas dominated by large crevasses. Numéro de notice : A2013-411 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2013.04.010 En ligne : https://doi.org/10.1016/j.isprsjprs.2013.04.010 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32549
in ISPRS Journal of photogrammetry and remote sensing > vol 82 (August 2013) . - pp 49 - 62[article]Réservation
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