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Generalization of DEM for terrain analysis using a compound method / Q. Zhou in ISPRS Journal of photogrammetry and remote sensing, vol 66 n° 1 (January - February 2011)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 66 n° 1 (January - February 2011) . - pp 38 - 45 Titre : Generalization of DEM for terrain analysis using a compound method Type de document : Article/Communication Auteurs : Q. Zhou, Auteur ; Y. Chen, Auteur Année de publication : 2011 Article en page(s) : pp 38 - 45 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique [Termes IGN] erreur moyenne quadratique [Termes IGN] généralisation automatique de données [Termes IGN] généralisation de MNT [Termes IGN] modèle numérique de surface [Termes IGN] Triangulated Irregular Network Résumé : (Auteur) This paper reports an investigation into the generalization of a grid-based digital elevation model (DEM) for the purpose of terrain analysis. The focus is on the method of restructuring the grid-based surface elevation data to form a triangulated irregular network (TIN) that is optimized to keep the important terrain features and slope morphology with the minimum number of sample points. The critical points of the terrain surface are extracted from the DEM based on their significance, measured not only by their local relief, but also by their importance in identifying inherent geomorphological and drainage features in the DEM. A compound method is proposed by integrating the traditional point-additive and feature-point methods to construct a drainage-constrained TIN. The outcome is then compared with those derived from other selected methods including filtering, point-additive or feature-point algorithms. The results show that the compound approach is capable of taking advantage of both point-additive and feature-point algorithms to maximally keep the terrain features and to maintain RMSE at an acceptable level, while reducing the elevation data points by over 99%. The analytical result also shows that the proposed method outperforms the compared methods with better control in retaining drainage features at the same level of RMSE. Numéro de notice : A2011-015 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2010.08.005 En ligne : https://doi.org/10.1016/j.isprsjprs.2010.08.005 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30797 [article]

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Relevance of airborne lidar and multispectral image data for urban scene classification using random forests / Li Guo in ISPRS Journal of photogrammetry and remote sensing, vol 66 n° 1 (January - February 2011)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 66 n° 1 (January - February 2011) . - pp 56 - 66 Titre : Relevance of airborne lidar and multispectral image data for urban scene classification using random forests Type de document : Article/Communication Auteurs : Li Guo, Auteur ; Nesrine Chehata , Auteur ; Clément Mallet , Auteur ; Samia Boukir, Auteur Année de publication : 2011 Article en page(s) : pp 56 - 66 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] analyse discriminante [Termes IGN] classification dirigée [Termes IGN] classification par forêts d'arbres décisionnels [Termes IGN] données lidar [Termes IGN] écho multiple [Termes IGN] forme d'onde pleine [Termes IGN] image multibande [Termes IGN] semis de points [Termes IGN] zone urbaine dense Résumé : (Auteur) Airborne lidar systems have become a source for the acquisition of elevation data. They provide georeferenced, irregularly distributed 3D point clouds of high altimetric accuracy. Moreover, these systems can provide for a single laser pulse, multiple returns or echoes, which correspond to different illuminated objects. In addition to multi-echo laser scanners, full-waveform systems are able to record 1D signals representing a train of echoes caused by reflections at different targets. These systems provide more information about the structure and the physical characteristics of the targets. Many approaches have been developed, for urban mapping, based on aerial lidar solely or combined with multispectral image data. However, they have not assessed the importance of input features. In this paper, we focus on a multi-source framework using aerial lidar (multi-echo and full waveform) and aerial multispectral image data. We aim to study the feature relevance for dense urban scenes. The Random Forests algorithm is chosen as a classifier: it runs efficiently on large datasets, and provides measures of feature importance for each class. The margin theory is used as a confidence measure of the classifier, and to confirm the relevance of input features for urban classification. The quantitative results confirm the importance of the joint use of optical multispectral and lidar data. Moreover, the relevance of full-waveform lidar features is demonstrated for building and vegetation area discrimination. Numéro de notice : A2011-016 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2010.08.007 Date de publication en ligne : 22/09/2010 En ligne : https://doi.org/10.1016/j.isprsjprs.2010.08.007 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30798 [article]

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Orthorectification of VHR optical satellite data exploiting the geometric accuracy of TerraSAR-X data / Peter Reinartz in ISPRS Journal of photogrammetry and remote sensing, vol 66 n° 1 (January - February 2011)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 66 n° 1 (January - February 2011) . - pp 124 - 132 Titre : Orthorectification of VHR optical satellite data exploiting the geometric accuracy of TerraSAR-X data Type de document : Article/Communication Auteurs : Peter Reinartz, Auteur ; R. Muller, Auteur ; P. Schwind, Auteur ; et al., Auteur Année de publication : 2011 Article en page(s) : pp 124 - 132 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image mixte [Termes IGN] appariement d'images [Termes IGN] erreur moyenne quadratique [Termes IGN] image ALOS-PRISM [Termes IGN] image Ikonos [Termes IGN] image optique [Termes IGN] image radar [Termes IGN] image TerraSAR-X [Termes IGN] méthode robuste [Termes IGN] modèle par fonctions rationnelles [Termes IGN] orientation du capteur [Termes IGN] orthorectification [Termes IGN] point d'appui [Termes IGN] précision géométrique (imagerie) [Termes IGN] zone urbaine Résumé : (Auteur) Orthorectification of satellite data is one of the most important pre-processing steps for application oriented evaluations and for image data input into Geographic Information Systems. Although high- and very high-resolution optical data can be rectified without ground control points (GCPs) using an underlying digital elevation model (DEM) to positional root mean square errors (RMSEs) between 3 m and several hundred meters (depending on the satellite), there is still need for ground control with higher precision to reach lower RMSE values for the orthoimages. The very high geometric accuracy of geocoded data of the TerraSAR-X satellite has been shown in several investigations. This is due to the fact that the SAR antenna measures distances which are mainly dependent on the terrain height and the position of the satellite. The latter can be measured with high precision, whereas the satellite attitude need not be known exactly. If the used DEM is of high accuracy, the resulting geocoded SAR data are very precise in their geolocation. This precision can be exploited to improve the orientation knowledge and thereby the geometric accuracy of the rectified optical satellite data. The challenge is to match two kinds of image data, which exhibit very different geometric and radiometric properties. Simple correlation techniques do not work and the goal is to develop a robust method which works even for urban areas, including radar shadows, layover and foreshortening effects. First the optical data have to be rectified with the available interior and exterior orientation data or using rational polynomial coefficients (RPCs). From this approximation, the technique used is the measurement of small identical areas in the optical and radar images by automatic image matching, using a newly developed adapted mutual information procedure followed by an estimation of correction terms for the exterior orientation or the RPC coefficients. The matching areas are selected randomly from a regular grid covering the whole imagery. By adjustment calculations, parameters from falsely matched areas can be eliminated and optimal improvement parameters are found. The original optical data are orthorectified again using the delivered metadata together with these corrections and the available DEM. As proof of method the orthorectified data from IKONOS and ALOS-PRISM sensors are compared with conventional ground control information from high-precision orthoimage maps of the German Cartographic Survey. The results show that this method is robust, even for urban areas. Although the resulting RMSE values are in the order of 2–6 m, the advantage is that this result can be reached even for optical sensors which do not exhibit low RMSE values without using manual GCP measurements. Numéro de notice : A2011-017 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2010.10.003 En ligne : https://doi.org/10.1016/j.isprsjprs.2010.10.003 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30799 [article]

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081-2011011	SL	Revue	Centre de documentation	Revues en salle	Disponible