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Surface reconstruction based on forest terrestrial LiDAR data / Jules Morel (2017)  

Public Titre : Surface reconstruction based on forest terrestrial LiDAR data Type de document : Thèse/HDR Auteurs : Jules Morel, Auteur ; Marc Daniel, Directeur de thèse ; Cédric Vega , Directeur de thèse ; Alexandra Bac, Directeur de thèse Editeur : Aix-en-Provence : Université d'Aix-Marseille Année de publication : 2017 Importance : 178 p. Format : 21 x 30 cm Note générale : bibliographie A dissertation presented to the Department of Mathématique et Informatique in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the subject of Computer Science Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] distribution de Poisson [Termes IGN] données lidar [Termes IGN] données TLS (télémétrie) [Termes IGN] fonction de base radiale [Termes IGN] interpolation [Termes IGN] modélisation de la forêt [Termes IGN] placette d'échantillonnage [Termes IGN] reconstruction d'objet [Termes IGN] semis de points [Termes IGN] structure d'un peuplement forestier [Termes IGN] structure de la végétation Index. décimale : THESE Thèses et HDR Résumé : (auteur) In recent years, the capacity of LiDAR technology to capture detailed information about forests structure has attracted increasing attention in the field of forest science. In particular, the terrestrial LiDAR arises as a promising tool to retrieve geometrical characteristics of trees at a millimeter level. This thesis studies the surface reconstruction problem from scattered and unorganized point clouds, captured in forested environment by a terrestrial LiDAR. We propose a sequence of algorithms dedicated to the reconstruction of forests plot attributes model: the ground and the woody structure of trees (i.e. the trunk and the main branches). In practice, our approaches model the surface with implicit function build with radial basis functions to manage the homogeneity and handle the noise of the sample data points. Our first focus is on the reconstruction of the ground surface whose level of detail is based on local complexity, through alternation between scale refinement, filtering and reconstruction. The result arises from the polygonization of the implicit function expressed as the merging of local approximations by compactly supported radial basis function used as partition of unity. Once the ground is modeled, the topology effects can be ignored in the following computation steps that focus on the modeling of trees. Traditionally, the processing of the woody part is achieved by a discrete reconstruction in the form of a stack of independent building blocks. From such a model, our approach developed for the ground is adapted to approximate the woody part of the tree by a more flexible continuous surface. Expressed as an implicit function, the tree model can be refined by an additional computational step in order to describe precisely the geometry. With this in mind, we propose a method dedicated to the fine reconstruction of occluded objects: from 3D samples presenting occlusions, we use the previously described continuous model to guide a Poisson surface reconstruction. Thus, we guarantee the production of a watertight surface that approximates sharply the point cloud in the visible areas and extrapolates consistently the tree shape in the occlusions. Note de contenu : 1- Introduction 2- Terrestrial LiDAR scanning in forests 3- Survey on surface reconstruction 4- Reconstruction of open surface 5- Geometric model of trees 6- Reconstruction of partially occluded objects 7- Conclusion and perspectives Numéro de notice : 25855 Affiliation des auteurs : LIF+Ext (2012-2019) Thématique : IMAGERIE Nature : Thèse française Note de thèse : PhD Thesis: Computer Science : Marseille : 2017 Organisme de stage : Institut Français de Pondichéri (Inde) nature-HAL : Thèse DOI : sans En ligne : http://www.theses.fr/2017AIXM0039 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95472

Conflict removal between B-spline curves for isobathymetric line generalization using a snake model / E. Guilbert in Cartography and Geographic Information Science, vol 33 n° 1 (January 2006)  

Public [article]  inCartography and Geographic Information Science > vol 33 n° 1 (January 2006) . - pp 37 - 52 Titre : Conflict removal between B-spline curves for isobathymetric line generalization using a snake model Type de document : Article/Communication Auteurs : E. Guilbert, Auteur ; Eric Saux, Auteur ; Marc Daniel, Auteur Année de publication : 2006 Article en page(s) : pp 37 - 52 Langues : Anglais (eng) Descripteur : [Termes IGN] algorithme snake [Termes IGN] B-Spline [Termes IGN] base de données bathymétriques [Termes IGN] bathymétrie [Termes IGN] cohérence des données [Termes IGN] conflit d'espace [Termes IGN] généralisation cartographique automatisée [Termes IGN] isobathe [Termes IGN] polyligne [Vedettes matières IGN] Généralisation Résumé : (Auteur) This paper describes a method for suppressing distance conflicts between isobathymetric lines modeled with B-spline curves for cartographic generalization. The initial B-spline curves are obtained by compressing a set of polygonal lines representing the raw data. The conflict removal is realized by respecting strong cartographic constraints, such as the navigation safety and the legibility of the map, and weak constraints, such as the preservation of the submarine relief. A polygonal line representing the minimal displacement that corrects a conflict is first computed. Then, the curve is deformed using a snake model. The constraints are expressed via different energy terms, and the curve is deformed until a valid solution is reached. In order to apply the method without user intervention, the shape parameters of the snake are set automatically. The advantage of the method is that it ensures the respect of strong constraints in every case while taking into account the weaker ones. The method can also be applied to the correction of visual self-intersections. The use of a snake model combined with B-spline curves permits a better control of the deformation than polygonal lines better preserving of the shape of the curves. Examples of real case studies issued from bathymetric databases are provided, and the benefits and drawbacks of the method are discussed. Copyright CaGISociety Numéro de notice : A2006-204 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/INFORMATIQUE Nature : Article DOI : 10.1559/152304006777323145 En ligne : https://doi.org/10.1559/152304006777323145 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27931 [article]

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