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Planimetric simplification and lexicographic optimal chains for 3D urban scene reconstruction / Julien Vuillamy (2021)  

Public Titre : Planimetric simplification and lexicographic optimal chains for 3D urban scene reconstruction Type de document : Thèse/HDR Auteurs : Julien Vuillamy, Auteur ; Pierre Alliez, Directeur de thèse Editeur : Nice : Université Côte d'Azur Année de publication : 2021 Importance : 129 p. Format : 21 x 30 cm Note générale : bibliographie Thèse Présentée en vue de l’obtention du grade de docteur en Informatique d’Université Côte d’Azur Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] complexe simplicial [Termes IGN] géométrie de Riemann [Termes IGN] homologie [Termes IGN] maillage [Termes IGN] modèle 3D de l'espace urbain [Termes IGN] optimisation (mathématiques) [Termes IGN] programmation linéaire [Termes IGN] reconstruction 3D du bâti [Termes IGN] scène urbaine [Termes IGN] semis de points [Termes IGN] simplification de surface [Termes IGN] triangulation de Delaunay Index. décimale : THESE Thèses et HDR Résumé : (auteur) Creating mesh representations for urban scenes is a requirement for numerous modern applications of urban planning ranging from visualization, inspection, to simulation. Adding to the diversity of possible input data -- photography, laser-based acquisitions and existing geographical information system (GIS) data, the variety of urban scenes as well as the large-scale nature of the problem makes for a challenging line of research. Working towards an automatic approach to this problem suggests that a one-fits-all method is hardly realistic. Two independent approaches of reconstruction from point clouds have thus been investigated in this work, with radically different points of view intended to cover a large number of use cases. In the spirit of the GIS community, the first approach makes strong assumptions on the reconstructed scenes and creates a 2.5D piecewise-planar representation of buildings using an intermediate 2D cell decomposition. Constructing these decompositions from noisy or incomplete data often leads to overly complex representations, which lack the simplicity or regularity expected in this context of reconstruction. Loosely inspired by clustering problems such as mean-shift, the focus is put on simplifying such partitions by formulating an optimization process based on a tradeoff between attachment to the original partition and objectives striving to simplify and regularize the arrangement. This method involves working with point-line duality, defining local metrics for line movements and optimizing using Riemannian gradient descent. The second approach is intended to be used in contexts where the strong assumptions on the representation of the first approach do not hold. We strive here to be as general as possible and investigate the problem of point cloud meshing in the context of noisy or incomplete data. By considering a specific minimization, corresponding to lexicographic orderings on simplicial chains, polynomial-time algorithms finding lexicographic optimal chains, homologous to a given chain or bounded by a given chain, are derived from algorithms for the computation of simplicial persistent homology. For pseudomanifold complexes in codimension 1, leveraging duality and an augmented version of the disjoint-set data structure improves the complexity of these problem instances to quasi-linear time algorithms. By combining its uses with a sharp feature detector in the point cloud, we illustrate different use cases in the context of urban reconstruction. Note de contenu : 1- Introduction 2- State of the art and contributions 3- Parsimonious representations from 2D partitions 4- Dense representations from lexicographic optimal chains 5- Conclusion and perspectives Numéro de notice : 28655 Affiliation des auteurs : non IGN Thématique : IMAGERIE/INFORMATIQUE Nature : Thèse française Note de thèse : Thèse de Doctorat : Informatique : Côte d'Azur : 2021 Organisme de stage : INRIA DOI : sans En ligne : https://hal.science/tel-03339931 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99797