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A multi-resolution approach for filtering LiDAR altimetry data / José L. Silvan-Cardenas in ISPRS Journal of photogrammetry and remote sensing, vol 61 n° 1 (October 2006)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 61 n° 1 (October 2006) . - pp 11 - 22 Titre : A multi-resolution approach for filtering LiDAR altimetry data Type de document : Article/Communication Auteurs : José L. Silvan-Cardenas, Auteur ; L. Wang, Auteur Année de publication : 2006 Article en page(s) : pp 11 - 22 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] convolution (signal) [Termes IGN] données altimétriques [Termes IGN] données lidar [Termes IGN] filtrage du signal [Termes IGN] gradient de pente [Termes IGN] lissage de données [Termes IGN] modèle numérique de surface [Termes IGN] modèle numérique de terrain Résumé : (Auteur) Discrimination of above-ground objects from terrain has proven to be surprisingly difficult to automate in computers, especially for large areas of varied terrain characteristics. Several methods have been developed for filtering the LiDAR data, of which three approaches are more prevalent: linear prediction, slope based and morphological filtering. A common ground to all these approaches is that the range of scales at which feature variations exist tends to be smaller than the range of scales at which terrain variations exist. In this paper, a model-based approach is described in which multiscale gradient of the surface variation is computed and used to adaptively erode the gridded LiDAR data within a multi-resolution, analysis–synthesis framework, namely the multiscale Hermite transform (MHT). The method was tested over nineteen datasets, including urban and forest areas. An average coefficient of agreement was computed over all datasets and compared with that obtained from other methods. Results showed that the proposed method was within the top three among nine methods tested. Copyright ISPRS Numéro de notice : A2006-438 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2006.06.002 En ligne : https://doi.org/10.1016/j.isprsjprs.2006.06.002 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28162 [article]

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Semantically correct 2.5D GIS data: the integration of a DTM and topographic vector data / A. Koch in ISPRS Journal of photogrammetry and remote sensing, vol 61 n° 1 (October 2006)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 61 n° 1 (October 2006) . - pp 23 - 32 Titre : Semantically correct 2.5D GIS data: the integration of a DTM and topographic vector data Type de document : Article/Communication Auteurs : A. Koch, Auteur ; Christian Heipke, Auteur Année de publication : 2006 Article en page(s) : pp 23 - 32 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bases de données localisées [Termes IGN] données localisées 2D [Termes IGN] intégration de données [Termes IGN] modèle numérique de terrain [Termes IGN] précision sémantique [Termes IGN] qualité sémantique [Termes IGN] Triangulated Irregular Network [Termes IGN] triangulation de Delaunay Résumé : (Auteur) The most commonly used topographic vector data, the reference data of national geographic information systems (GIS) are currently two-dimensional. The topography is modelled by different objects which are represented by single points, lines and areas with additional attributes containing information, for instance on the function and size of the object. In contrast, a digital terrain model (DTM) in most cases is a 2.5D representation of the earth's surface. The integration of the two data sets leads to an augmentation of the dimension of the topographic objects. However, due to inconsistencies between the data the integration process may lead to semantically incorrect results. This paper presents a new approach for the integration of a DTM and 2D GIS vector data including the re-establishment of the semantic correctness of the integrated data set. The algorithm consists of two steps. In the first step the DTM and the topographic objects are integrated without considering the semantics of the objects. This geometric integration is based on a DTM TIN (triangular irregular network) computed using a constrained Delaunay triangulation. In the second step those objects which contain implicit height information are further utilized: object representations are formulated and the semantics of the objects are considered within an optimization process using equality and inequality constraints. The algorithm is based on an inequality constrained least squares adjustment formulated as the linear complementary problem (LCP). The algorithm results in an integrated semantically correct 2.5D GIS data set. Results are presented using simulated and real data. Lakes represented by horizontal planes with increasing terrain outside the lake and roads which are composed of several tilted planes were investigated. The algorithm shows satisfying results: the constraints are fulfilled and the visualization of the integrated data set corresponds to the human view of the topography. Copyright ISPRS Numéro de notice : A2006-439 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/INFORMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2006.07.005 En ligne : https://doi.org/10.1016/j.isprsjprs.2006.07.005 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28163 [article]

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Bridge detection in airborne laser scanner data / George Sithole in ISPRS Journal of photogrammetry and remote sensing, vol 61 n° 1 (October 2006)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 61 n° 1 (October 2006) . - pp 33 - 46 Titre : Bridge detection in airborne laser scanner data Type de document : Article/Communication Auteurs : George Sithole, Auteur ; M. George Vosselman, Auteur Année de publication : 2006 Article en page(s) : pp 33 - 46 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] détection du bâti [Termes IGN] données lidar [Termes IGN] pont [Termes IGN] segmentation d'image [Termes IGN] semis de points Résumé : (Auteur) In a landscape bridges are ambiguous features in that they are extensions of the bare earth but they are also man made. Therefore, in a Digital Terrain Model (DTM) generation, depending on application it is necessary to keep or remove bridges. For this reason they have to be detected explicitly. A geometric bridge detection algorithm is proposed that is based on the idea that features can be detected in a landscape based on cross-sections (profiles) in a landscape. The topological information contained in the cross-sections are used to identify seed bridge points. The seed bridge points are then used to detect individual bridges. The bridge detection algorithm is novel in that the algorithm is blind to the shape of a bridge and is adaptable to different bridge designs. Therefore, bridges need not have parallel edges or uniform width. Furthermore, bridges can curve, split into parts, and contain holes. The bridge detection algorithm has been tested on various data sets and found to work very well in detecting bridges. Copyright ISPRS Numéro de notice : A2006-440 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2006.07.004 En ligne : https://doi.org/10.1016/j.isprsjprs.2006.07.004 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28164 [article]

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Rigorous approach to bore-sight self-calibration in airborne laser scanning [erratum in vol 61 n° 6 February 2007, pages 414-415] / Jan Skaloud in ISPRS Journal of photogrammetry and remote sensing, vol 61 n° 1 (October 2006)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 61 n° 1 (October 2006) . - pp 47 - 59 Titre : Rigorous approach to bore-sight self-calibration in airborne laser scanning [erratum in vol 61 n° 6 February 2007, pages 414-415] Type de document : Article/Communication Auteurs : Jan Skaloud, Auteur ; Derek D. Lichti, Auteur Année de publication : 2006 Article en page(s) : pp 47 - 59 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes IGN] angle de visée [Termes IGN] auto-étalonnage [Termes IGN] données lidar [Termes IGN] géoréférencement direct [Termes IGN] GPS-INS [Termes IGN] ligne de visée [Termes IGN] télémétrie laser aéroporté Résumé : (Auteur) We present a rigorous method for estimating some of the calibration parameters in airborne laser scanning (ALS), namely the three bore-sight angles and the range-finder offset. The technique is based on expressing the system calibration parameters within the direct-georeferencing equation separately for each target point, and conditioning a group of points to lie on a common surface of a known form such as a plane. However, the assumed a priori information about á chosen planar features is only their form not the spatial orientation or position. Thus, the 4·á plane parameters are estimated together with the calibration parameters in a combined adjustment model that makes use of GPS/INS-derived position and orientation as well as LiDAR range and encoder angle as observations. To make the approach practical when working with voluminous ALS and GPS/INS data, the contribution of each laser point to the normal equations is formed sequentially. The discussions focus on practical examples with data from a continuously-rotating scanner that reveal the conditions under which almost complete de-correlation between the estimated parameters occurs. In such a case, all bore-sight angles are determined with accuracy that is several times superior to the system noise level. Given sufficiently strong geometry, the presented method is shown to be not only accurate but also very robust in terms of convergence. When appropriate, the method is applicable for calibration of additional systematic effects such as laser-beam encoder offsets or scale factor with minimal modification to the functional model. Copyright ISPRS Numéro de notice : A2006-441 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2006.07.003 En ligne : https://doi.org/10.1016/j.isprsjprs.2006.07.003 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28165 [article]

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