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Ground target tracking and road map extraction / W Koch in ISPRS Journal of photogrammetry and remote sensing, vol 61 n° 3-4 (December 2006)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 61 n° 3-4 (December 2006) . - pp 197 - 208 Titre : Ground target tracking and road map extraction Type de document : Article/Communication Auteurs : W Koch, Auteur ; J. Koller, Auteur ; M. Ulmke, Auteur Année de publication : 2006 Article en page(s) : pp 197 - 208 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] classification bayesienne [Termes IGN] extraction du réseau routier [Termes IGN] image aérienne [Termes IGN] image radar [Termes IGN] précision des données [Termes IGN] trafic routier Résumé : (Auteur) For analyzing dynamic scenarios with many ground moving vehicles, airborne Ground Moving Target Indicator (GMTI) radar is well-suited due to its wide-area, all-weather, day/night, and real time capabilities. The generation of GMTI tracks from these data is the backbone for ground surveillance and traffic flow analysis. In case of dense target situations, missing detections and false alarms, Multi-Hypotheses Tracking (MHT) is the method at choice to solve the inherent ambiguities in the data-targets assignment problem. The resulting MHT-tracks are suited to extract road map information which is highly up-to-date and fairly precise. Moreover, their accuracy is quantitatively described. The precision of the extracted road segments can be improved significantly using smoothed or retrodicted tracks. In turn, the extracted road information is exploited for the precise tracking of succeeding road targets. The proposed, fully Bayesian approach is illustrated by a simulated example including Doppler and terrain obscuration, providing hints to the achievable road map accuracies. Numéro de notice : A2006-604 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2006.09.013 En ligne : https://doi.org/10.1016/j.isprsjprs.2006.09.013 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28327 [article]

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Code-barres	Cote	Support	Localisation	Section	Disponibilité
081-06091	RAB	Atlas / Beau livre	Centre de documentation	En réserve L003	Exclu du prêt

Wind resource assessment from C-band SAR / M.B. Christiansen in Remote sensing of environment, vol 105 n° 1 (15/11/2006)  

Public [article]  inRemote sensing of environment > vol 105 n° 1 (15/11/2006) . - pp 68 - 81 Titre : Wind resource assessment from C-band SAR Type de document : Article/Communication Auteurs : M.B. Christiansen, Auteur ; W Koch, Auteur Année de publication : 2006 Article en page(s) : pp 68 - 81 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] analyse comparative [Termes IGN] bande C [Termes IGN] direction [Termes IGN] écart type [Termes IGN] erreur systématique [Termes IGN] gradient [Termes IGN] image Envisat-ASAR [Termes IGN] image ERS-SAR [Termes IGN] Nord, mer du [Termes IGN] vent [Termes IGN] vitesse Résumé : (Auteur) Using accurate inputs of wind speed is crucial in wind resource assessment, as predicted power is proportional to the wind speed cubed. First, wind speeds retrieved from a series of 91 ERS-2 SAR and Envisat ASAR images, at moderate wind speeds (2–15 m s- 1), were validated against in situ measurements from an offshore mast in the North Sea. The wind direction input, necessary for SAR wind speed retrievals, was obtained from the meteorological mast and from a local gradient analysis of wind streaks in the SAR images. A wind speed standard deviation of not, vert, similar 1.1 m s- 1 was found when in situ wind directions were used. The use of local gradient wind directions yielded a standard deviation of not, vert, similar 1.3 m s- 1. Wind speeds retrieved from three geophysical model functions (CMOD-IFR2, CMOD4, and CMOD5) were compared. The best approximation to the in situ measurements of wind speed was found for CMOD-IFR2, despite a bias on the order of - 0.3 m s- 1. CMOD4 retrievals also underestimated the wind speed, whereas the bias on CMOD5 retrievals was negligible. Then, wind resource assessments were made from the SAR-based wind observations to show how errors in wind speed from the different SAR wind retrievals were reflected in the wind statistics. The mean wind speed, obtained for all of the 91 SAR scenes, was linked closely to the bias of SAR wind retrievals. Agreement to 1 15% of the in situ measurements was found for all the wind retrieval methods tested. The accuracy of power density estimates for the entire data set was evaluated by the standard deviation of SAR wind retrievals relative to the in situ measurements. SAR wind fields retrieved with CMOD-IFR2, using in situ wind direction inputs, exactly yielded the power density predicted from in situ measurements alone. The SAR-based wind resource assessment also corresponded well to predictions from longer time series of in situ measurements. This indicates that a reliable wind resource assessment may be achieved from a series of randomly selected SAR images. The findings presented here could be useful in future wind resource assessment based on SAR images. Copyright Elsevier Numéro de notice : A2006-503 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2006.06.005 En ligne : https://doi.org/10.1016/j.rse.2006.06.005 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28227 [article]