Papers by Sebastien Horna
The work presented in this paper is about comparison and analysis of four different reconstructio... more The work presented in this paper is about comparison and analysis of four different reconstruction methods applicable to MR images. Two of them are based on the marching cube algorithm and the other two are contour based algorithms. We describe the studied reconstruction methods and compare their results. The comparative study examined, allows to establish similarity, equivalence, or distinctness between the four methods. We show that the various reconstruction methods produce different 3D models and each one has its own advantages and limitations.
Proceedings, Aug 29, 2016
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
72nd EAGE Conference and Exhibition incorporating SPE EUROPEC 2010, 2010
HAL (Le Centre pour la Communication Scientifique Directe), Jun 10, 2006
poitiers.fr Résumé Cet article présente une nouvelle méthode de reconstruction d'un modèle topolo... more poitiers.fr Résumé Cet article présente une nouvelle méthode de reconstruction d'un modèle topologique représentant des bâtimentsà partir de données existantes. A long terme, notre objectif est de produire une description 3Dà partir de plans d'architectes 2D (numériques mais non numérisés). Le modèle topologique déduit peut serviràéditer les modèles 2D/3D, en utilisant des opérations classiques de modélisation (arrondis, extrusions, etc.). Notre méthode se déroule de la manière suivante. Dans un premier temps, les arêtes décrivant la géométrie du plan donné sont traitées pour supprimer les arêtes confondues et gérer les intersections. La seconde partie de l'algorithme consisteà associer une structure topologiqueà la géométrie pour déduire toutes les relations d'incidence et d'adjacence entre les arêtes. Uneétape de finalisation est rendue possible grâceà une série d'opérations offerteà l'utilisateur pour traiter les cas ambigus et corriger les plans. Auxétapes les plus coûteuses, une structure accélératrice est placée dans la scène pour réduire les temps de calcul.
Simulation d'éclairage par tracé de photons pour de grands bâtiments
HAL (Le Centre pour la Communication Scientifique Directe), Jun 10, 2005
The effects of delayed pinching on chrysanthemums
Acceleration structures are mandatory for ray-tracing applications, allowing to cast a large numb... more Acceleration structures are mandatory for ray-tracing applications, allowing to cast a large number of rays per second. In 2008, Lagae and Dutré have proposed to use Constrained Delaunay Tetrahedralization (CDT) as an acceleration structure for ray tracing. Our experiments show that their traversal algorithm is not suitable for GPU applications, mainly due to arithmetic errors. This article proposes a new CDT traversal algorithm. This new algorithm is more efficient than the previous ones: it uses less arithmetic operations; it does not add extra thread divergence since it uses a fixed number of operation; at last, it is robust with 32-bits floats, contrary to the previous traversal algorithms. Hence, it is the first method usable both on CPU and GPU. This article is organized as follows: Section 2 recapitulates previous CDT works. Section 3 presents our new CDT traversal. Section 4 discusses our experiments. Finally, Section 5 concludes this paper. 2 PREVIOUS WORKS ON CDT This section first describes CDT, then it presents its construction from a geometric model, before focusing on former ray traversal methods. 2.1 CDT Description A Delaunay tetrahedralization of a set of points X ∈ E 3 is a set of tetrahedra occupying the whole
2D and 3D virtual architectural models are the common ground of many studies, including environme... more 2D and 3D virtual architectural models are the common ground of many studies, including environmental protection, energy saving, or human well-being. Building or urban environment simulations concern for instance heat transfer, lighting, and acoustics, each of them requiring physical parameters additionally to the geometric representation. Furthermore, geometry does not generally comply straightforwardly with physical parameters and users are forced to manually adapt the models before simulation. This paper proposes an overview of modeling and simulation studies that make use of topological representations, and discusses the advantages of a topological representation for various types of applications. Such a representation can be used not only to maintain the 3D model global coherence, but also to automatically retrieve walls, doors, or room volumes for instance. Based on the existing model of generalized maps, this paper also illustrates some examples of structure traversal that ca...
Advances in Computer Graphics, 2019
Many manufactured objects and worn surfaces exhibit rounded corners and edges. These fine details... more Many manufactured objects and worn surfaces exhibit rounded corners and edges. These fine details are a source of sharp highlights and shading effects, important to our perception between joining surfaces. However, their representation is often neglected because they introduce complex geometric meshing in very small areas. This paper presents a new method for managing thin rounded corners and edges without explicitly modifying the underlying geometry, so as to produce their visual effects in sample-based rendering algorithms (e.g., ray tracing and path tracing). Our method relies on positioning virtual spheres and cylinders, associated with a detection and acceleration structure that makes the process more robust and more efficient than existing bevel shaders. Moreover, using our implicit surfaces rather than polygonal meshes allows our method to generate extreme close views of the surfaces with a much better visual quality for little additional memory. We illustrate the achieved effects and analyze comparisons generated with existing industrial software shaders.
72nd EAGE Conference and Exhibition incorporating SPE EUROPEC 2010, 2010
12th European Conference on the Mathematics of Oil Recovery, Sep 6, 2010
In traditional methods used to populate stratigraphic units, the distortions can be very importan... more In traditional methods used to populate stratigraphic units, the distortions can be very important and affect the setting up of the static and dynamic parameters necessary to the reservoir simulation, hence the simulation results. These distortions result from the mapping between the original curvilinear stratigraphic grid and the intermediate cartesian grid in which the property populating is processed. To minimize the deformation and improve the populating process, we propose a new original isometric unfolding process based on the minimization of the elastic tensor deformation. This method could be applied for every type of deposit: horizontal, parallel to top, parallel to bottom, proportional. Starting from a structural model defined into a coordinate line grid, the user chooses a reference iso-chronological level represented by a triangulated surface. This level can be the top, the bottom or any other characteristic surface of a litho stratigraphic unit. The contacts between this surface and fault surfaces are explicitly extracted as coincident edges. These coincident edges are used to constraint an unfolding process which minimizes the elastic deformation tensor on the whole surface and then, respecting the above constraints, join the fault lips opened by geological tectonic events. New aspects covered : We propose a new original isometric unfolding process based on the minimization of the elastic tensor deformation. We apply this algorithm to unfold iso-chronological surfaces and to unfold volumes in several depositional modes: Top and bottom conformable, proportional and parallel to any surface.
Computer-Aided Design and Applications, 2019
Digital 3D models are widely used in many application elds. While the models are required by seve... more Digital 3D models are widely used in many application elds. While the models are required by several applications, such as architecture, geoscience or simulation, they often lack vital information for the nal business application. Models are therefore often rebuilt to meet the requirements of a specic application. Unfortunately, this reconstruction is a tedious task and consumes time and resources. This paper presents a general algorithm for reconstructing 3D objects with 3D topological information and without geometrical inconsistencies. Firstly, a cellular subdivision is performed by relying on geometrical input data and then topological relationships between cells are explicitly dened. A 3D generalized map (3-G-map) data structure handles reconstruction information. Secondly, faces are split along their intersections in order to satisfy a space partition constraint and built a set of volume without overlapping. One of our notable contribution consists in solving the problem of 3D intersection by using topological information to improve speed performance and to handle geometrical imprecision.
Reconstruction géométrique et topologique de complexes architecturaux 3D à partir de plans numériques 2D
Http Www Theses Fr, 2008
L’interieur des bâtiments est souvent modelise en 3D pour diverses applications de modelisation o... more L’interieur des bâtiments est souvent modelise en 3D pour diverses applications de modelisation ou de simulation. Par exemple, plusieurs methodes permettent d’etudier l’eclairage, les transferts de chaleur, la propagation d’ondes. Ces applications necessitent dans la plupart des cas une representation volumique de l’environnement avec des relations d’adjacence et d’incidence entre les elements. Malheureusement, les donnees correspondant au bâtiment sont en general seulement disponibles en 2D et les besoins des applications 3D varient d’une utilisation a l’autre. Pour resoudre ce probleme, nous proposons une description formelle d’un ensemble de contraintes de coherence dediees a la modelisation d’interieur de bâtiments. Dans cette these nous montrons comment cette representation est utilisee pour : (i) reconstruire un modele 3D a partir de plans d’architecte numeriques 2D ; (ii) detecter automatiquement les incoherences geometriques, topologiques et semantiques ; (iii) developper des operations automatiques et semi-automatiques pour corriger les plans 2D. Toutes les contraintes de coherence sont definies en 2D et 3D et reposent sur le modele topologique des cartes generalisees. Ces operations sont utilisees pour editer les scenes 2D et 3D afin d’affiner ou de modifier les modeles. Enfin, nous expliquons comment ce modele est utilise pour une application de visualisation par lance de rayons.
Computer-Aided Design, 2009
Virtual architectural (indoor) scenes are often modeled in 3D for various types of simulation sys... more Virtual architectural (indoor) scenes are often modeled in 3D for various types of simulation systems. For instance, some authors propose methods dedicated to lighting, heat transfer, acoustic or radiowave propagation simulations. These methods rely in most cases on a volumetric representation of the environment, with adjacency and incidence relationships. Unfortunately, many buildings data are only given by 2D plans and the 3D needs varies from one application to another. To face these problems, we propose a formal representation of consistency constraints dedicated to building interiors and associated with a topological model. We show that such a representation can be used for: (i) reconstructing 3D models from 2D architectural plans (ii) detecting automatically geometrical, topological and semantical inconsistencies (iii) designing automatic and semi-automatic operations to correct and enrich a 2D plan. All our constraints are homogeneously defined in 2D and 3D, implemented with generalized maps and used in modeling operations. We explain how this model can be successfully used for lighting and radiowave propagation simulations.
Recontruction topologique de complexe architecturaux à partir de données numériques
Cet article présente une méthode de reconstruction géométrique et topologique 3D de bâtiments à p... more Cet article présente une méthode de reconstruction géométrique et topologique 3D de bâtiments à partir de plans vectoriels 2D. Dans un premier temps, un filtrage est appliqué aux arêtes du plan. L'objectif est de réaliser un nettoyage pour supprimer les arêtes confondues et gérer les intersections. Ensuite nous ajoutons une structure topologique pour déduire les relations d'incidence et d'adjacence entre les arêtes et former des faces sur le plan 2D. Nous proposons plusieurs opérations d'édition semi automatiques pour résoudre les problèmes résiduels. Des données sémantiques permettent d'enrichir le modèle pour spécifier les ouvertures, les murs, les pièces, les escaliers, la façade, etc. L'extrusion du modèle pour générer un environnement 3D est réalisée en fonction des informations sémantiques. Enfin, les différents étages sont superposés, en utilisant les volumes correspondants aux sols et aux plafonds, afin d'obtenir un bâtiment complet.
Journal of Imaging, Apr 7, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
This paper presents a new method for reconstructing geometry and topology of 3D buildings from 2D... more This paper presents a new method for reconstructing geometry and topology of 3D buildings from 2D architectural plans. A complete topological model expresses incidence and adjacency relations between all the elements. It is necessary for both recovering accurately 2D information and constructing a coherent 3D building. Based on an existing topological kernel, several high-level operations have been developped in 2D for creating walls, portals, stairs, etc. Semantic information is associated with all volumes for specifying openings, walls, rooms, stairs, facade, etc. The resulting 2D model is extruded for generating a 3D environment, taking the semantic information into account since doors are not processed as walls for instance. Floors are superimposed using volumes corresponding to upper and lower ceilings linked according to stairways. The resulting models are suitable for various application such as walkthrough, lighting/wave propoagation/thermal simulation.
Reconstruction and topological cleaning of brain MR Images
2021 Sixth International Conference on Advances in Biomedical Engineering (ICABME)
Comparative Study of 3D Reconstruction Methods for Medical Imaging
CAD'21 Proceedings
The work presented in this paper is about comparison and analysis of four different reconstructio... more The work presented in this paper is about comparison and analysis of four different reconstruction methods applicable to MR images. Two of them are based on the marching cube algorithm and the other two are contour based algorithms. We describe the studied reconstruction methods and compare their results. The comparative study examined, allows to establish similarity, equivalence, or distinctness between the four methods. We show that the various reconstruction methods produce different 3D models and each one has its own advantages and limitations.
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Papers by Sebastien Horna