Towards recovery of complex shapes in meshes using digital images for reverse engineering applications

When an object owns complex shapes, or when its outer surfaces are simply inaccessible, some of its parts may not be captured during its reverse engineering. These deficiencies in the point cloud result in a set of holes in the reconstructed mesh. This paper deals with the use of information extracted from digital images to recover missing areas of a physical object. The proposed algorithm fills in these holes by solving an optimization problem that combines two kinds of information: (1) the geometric information available on the surrounding of the holes, (2) the information contained in an image of the real object. The constraints come from the image irradiance equation, a first-order non-linear partial differential equation that links the position of the mesh vertices to the light intensity of the image pixels. The blending conditions are satisfied by using an objective function based on a mechanical model of bar network that simulates the curvature evolution over the mesh. The inherent shortcomings both to the current holefilling algorithms and the resolution of the image irradiance equations are overcom

Towards recovery of complex shapes in meshes using digital images for reverse engineering applications

International audienceWhen an object owns complex shapes, or when its outer surfaces are simply inaccessible, some of its parts may not be captured during its reverse engineering. These deficiencies in the point cloud result in a set of holes in the reconstructed mesh. This paper deals with the use of information extracted from digital images to recover missing areas of a physical object. The proposed algorithm fills in these holes by solving an optimization problem that combines two kinds of information: (1) the geometric information available on the surrounding of the holes, (2) the information contained in an image of the real object. The constraints come from the image irradiance equation, a first-order non-linear partial differential equation that links the position of the mesh vertices to the light intensity of the image pixels. The blending conditions are satisfied by using an objective function based on a mechanical model of bar network that simulates the curvature evolution over the mesh. The inherent shortcomings both to the current holefilling algorithms and the resolution of the image irradiance equations are overcom

Towards an engineering approach for advanced interaction techniques in 3D environments

National audienceIn recent years, Virtual Environments have appeared in new areas such as mass-market, web or mobile situations. In parallel, advanced forms ofinteractions are emerging such as tactile, mixed, tangible or spatial user interfaces, promoting ease of learning and use. To contribute to the democratization of 3D Virtual Environments(3DVE) and their use by persons who are not experts in 3D and occasional users, simultaneously considering Computer Graphics and Human Computer Interaction design considerations is required. In this position paper, we first provide an overview of a new analytical framework for the design of advanced interaction techniques for 3D Virtual Environment. It consists in identifying links that support the interaction and connect user’s tasks to be performed in a 3DVE with the targeted scene graph. We relate our work to existing modeling approaches and discuss about our expectations with regards to the engineering of advanced interaction techniqu

Smartphone Based 3D Navigation Techniques in an Astronomical Observatory Context: Implementation and Evaluation in a Software Platform

International audience3D Virtual Environments (3DVE) come up as a good solution to transmit knowledge in a museum exhibit. In such contexts, providing easy to learn and to use interaction techniques which facilitate the handling inside a 3DVE is crucial to maximize the knowledge transfer. We took the opportunity to design and implement a software platform for explaining the behavior of the Telescope Bernard-Lyot to museum visitors on top of the Pic du Midi. Beyond the popularization of a complex scientific equipment, this platform constitutes an open software environment to easily plug different 3D interaction techniques. Recently, popular use of a smartphones as personal handled computer lets us envision the use of a mobile device as an interaction support with these 3DVE. Accordingly, we design and propose how to use the smartphone as a tangible object to navigate inside a 3DVE. In order to prove the interest in the use of smartphones, we compare our solution with available solutions: keyboard-mouse and 3D mouse. User experiments confirmed our hypothesis and particularly emphasizes that visitors find our solution more attractive and stimulating. Finally, we illustrate the benefits of our software framework by plugging alternative interaction techniques for supporting selection and manipulation task in 3D

Exploitation d'images numériques pour la simplification et la déformation de modèles polyédriques

Polyhedral models which are very often used in mechanical design, constitute a privileged representation among the digital mock-ups of products. On the one hand, the approaches and methods of manipulation and exploitation of these models are usually led by one geometric criterion linked to the objects' shape (normal, curvature ...) but only a few of them pay attention to perceptual information. On the other hand, the existing image processing techniques extract data (contours, geometric features, textures...) related to the objects' shapes description they represent. Thus, the goal of this Ph.D. is to perform a coupling between polyhedral 3D models and 2D digitalized image(s) in order to handle these models with image-based criteria. One simplification and two deformation methods are presented. In the first one, the simplification is based on a vertex removal iterative process led by a tolerance criterion: it is linked to images contours filtering which are projected onto the 3D model to identify areas which are more or less close to those character lines. The polyhedrons deformation methods are applied to the hole-filling case. A triangulation is inserted and deformed by an optimization problem under constraints resolution. The function to minimize simulates the curvature variation between the inserted patch and the initial model. The solution is obtained by an iterative algorithm based on a mechanical model of bars network. The constraints come either from the respect of 3D character lines obtained by stereoscopic triangulation or directly from the intensity of the pixels to constrain the vertices displacement to a certain elevation (inverse Shape From Shading problem). The three developed methods are completely modular.Les modèles polyédriques, très utilisés dans les processus d'ingénierie, constituent une représentation privilégiée au sein des maquettes numériques de produits. Les approches et méthodes de manipulation et d'exploitation de ces modèles, sont le plus souvent pilotées par un critère géométrique lié à la forme des objets (normale, courbure ...) mais très peu prennent en compte des informations de type perceptuelles. Parallèlement, les techniques de traitement d'images existantes extraient des données (contours, primitives géométriques, textures ...) relatives à la description des formes des objets qu'elles représentent. Ainsi, le but de cette thèse est de réaliser un couplage modèle polyédrique 3D / images numériques 2D pour manipuler les modèles 3D avec des critères extraits d'image(s). Une méthode de simplification et deux méthodes de déformation de polyèdres sont présentées. Dans la première méthode, la simplification est basée sur un processus itératif de suppression de sommets piloté par un critère de tolérance de simplification. Cette tolérance est liée au filtrage de contours d'image(s) qui sont projetés sur le modèle 3D afin d'identifier les zones plus ou moins proches de ces lignes de caractère. Les méthodes de déformation de polyèdres sont appliquées au cas du remplissage de trous. Une triangulation est insérée au modèle puis déformée par la résolution d'un problème d'optimisation numérique sous contraintes. La fonctionnelle à minimiser simule la variation de courbure entre le maillage inséré et le modèle initial. La solution est obtenue par un algorithme itératif basé sur un modèle mécanique de réseau de barres. Les contraintes imposent le respect de lignes de caractère 3D obtenues par triangulation stéréoscopique dans la première méthode, ou bien calculées en fonction de l'intensité lumineuse des pixels et qui imposent le déplacement des sommets correspondants suivant une certaine élévation (problème inverse du Shape From Shading). Les trois méthodes implémentées sont complètement modulaires

Reconstruction de formes complexes à partir d'images

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Reconstruction de formes complexes à partir d'images

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Crèation d'un site web pour un label

El trabajo propuesto consiste en la concepción y diseño de un sitio web para la empresa discográfica Vicious Circle, la partici
pación en un proyecto en equipo, de rediseño e integración de contenidos del sitio web MediaMag, y el cursado de una 
asignatura que aporta los conocimientos requeridos para el desarrollo de todo lo anterior. Como fichero MEMORIA queda adjunta la memoria del sitio web para la empresa discográfica. Como fichero ANEXOS queda adjunta la memoria del trabajo en equipo sobre el sitio web MediaMag

Collaboration numérisée et dépliage organisationnel : les f(r)ictions de la contribution créative

International audienceWe present a transversal university pedagogical project distributed over time and among many teachers and students. This project, although framed and formalised, leaves a large part to creativity, innovation and the emergence of a participatory organisation equipped and made possible by the use of different digital technologies. We mobilize the concept of heterotopia and rely on a communicational approach of organizations, to characterize the dynamics, work and infocommunicationnal skills of the collectives at work in the construction of this heterotopia. In particular, we will develop the figure of the organizational passers, essential for the construction, equipment and stabilization of heterotopia.Nous présentons un projet pédagogique universitaire transversal distribué dans le temps et entre de nombreux acteurs enseignants et étudiants. Ce projet quoique cadré et formalisé, laisse une grande part à la créativité, à l’innovation et à l’émergence d’une organisation participative équipée et rendue possible par le recours à différentes technologies numériques. Nous mobilisons le concept d’hétérotopie et prenons appui sur une approche communicationnelle de l’organisation, pour caractériser les dynamiques, le travail et les habiletés infocommunicationnelles des collectifs à l’œuvre dans la construction de cette hétérotopie. Nous développerons plus particulièrement la figure des passeurs organisationnels, essentiels à la construction, l’équipement et la stabilisation de l’hétérotopie

Activités de modélisation géométrique en conception intégrée

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