Publications

Abstract: This paper presents a framework for modeling, animating and morphing textured implicit models. Our hierarchical skeletal implicit surface model incorporates key-frame animation and procedural solid texturing in a unified and coherent way. Our system enables the designer to create complex special effects by synchronizing shape, animation and texture transformations.

Keywords: implicit surface modeling, animation, shape metamorphosis, texture metamorphosis, interpolation

Abstract: ???

Keywords: ???

Abstract: This paper presents algorithms for computing the distance between a point and a cylinder, a cone, a cylinder-sphere and a cone-sphere. Some optimizations are provided when queries are performed along a line which may be useful for ray tracing applications.

Keywords: distance computation.

Abstract: In this paper, we introduce a hybrid modeling framework for creating complex objects. Our system relies on an extended CSG tree that assembles skeletal implicit surfaces and polygonal meshes in a coherent fashion: we call this structure the HybridTree. Editing operations are performed by exploiting the complementary abilities of both implicit and parametric surface representations. Implicit surfaces are powerful for combining shapes with Boolean and blending operations, while polygonal meshes are well-suited for local deformations such as FFD and fast visualization. The evaluation of the HybridTree is performed on the fly either through field function queries when the implicit form is required, or through a mesh creation process which is specific and optimized for every kind of node. Both types of queries are achieved in a complete transparent way for the user.

Keywords: shape modeling, implicit surfaces, polygonal meshes, blending, free-form deformations.

Abstract: Recent research has demonstrated the effectiveness of complex skeletal primitives such as subdivision curves and surfaces in implicit surface modeling. This paper presents a hierarchichal modeling system with an automatic levels of detail management for a simpler modeling with an accelerated rendering. We manage levels of detail with smooth transitions and tree optimizations speeding up visualization by an order of magnitude, which allows an interactive editing of the shapes.

Keywords: modeling, implicit surfaces, complex skeletal primitives, levels of detail, accelerated rendering.

Abstract: In this paper, we introduce a hybrid modeling framework for creating complex objects. Our system relies on an extended CSG tree that assembles skeletal implicit surfaces and polygonal meshes in a coherent fashion: we call this structure the HybridTree. Editing operations are performed by exploiting the complementary abilities of both implicit and parametric surface representations. Implicit surfaces are powerful for combining shapes with Boolean and blending operations, while polygonal meshes are well-suited for local deformations such as FFD and fast visualization. The evaluation of the HybridTree is performed on the fly either through field function queries when the implicit form is required, or through a mesh creation process which is specific and optimized for every kind of node. Both types of queries are achieved in a complete transparent way for the user.

Keywords: shape modeling, implicit surfaces, polygonal meshes, blending, free-form deformations.

Abstract: This paper presents algorithms for computing the minimal distance between a point and a cylinder, a cone, a line swept sphere and a cone-sphere. Some optimizations are provided when queries are performed along a line which may be useful for voxelization applications. Source code is available online.

Keywords: distance computation.

Abstract: This paper presents algorithms for computing the distance between a point and a cylinder, a cone, a cylinder-sphere and a cone-sphere. Some optimizations are provided when queries are performed along a line which may be useful for ray tracing applications.

Keywords: ???

Abstract: Although many animation, deformation and metamorphosis techniques have been proposed, the simultaneous combination of those three transformations has never been addressed for three dimensional objects so far. This paper presents a framework for controlling metamorphosis between two animated implicit models built from skeletal elements. It relies on the animated BlobTree model that encompasses the animation and metamorphosis in an unified and coherent fashion. Our method is general and supports a wide range of animation systems such as key-frames or physically based systems.

Keywords: implicit surfaces, animation, metamorphosis.

Abstract: In general, skeletal implicit surfaces are created from simple skeletons such as point or line segments. Recent research demonstrated the power of subdivision curves and surfaces in implicit solid modeling. This paper aims at extending the scope of implicit modeling by introducing more complex skeletal primitives based on complex curves, surfaces and volumes, and by combining those primitives with local blending operators.
We demonstrate that complex primitives, which are very appealing for modeling a vast variety of shapes, may be processed efficiently and are compatible with interactive editing. We present several methods to handle those complex primitives. We adapt well-known tree optimization and balancing algorithms to speed-up computations. We also present some pre-processing methods that may be applied to a wide range of primitives and that may be invoked prior to ray-tracing or polygonization. Eventually, we describe the implementation of level of details primitives and nodes in our scene graph.
Eventually, we present several examples that demonstrate that our implicit modeling system can be used for modeling and animating complex shapes efficiently.

Keywords: implicit surfaces, complex skeletal primitives, levels of detail, local blending, accelerated rendering.

Abstract: Dans cet article, nous proposons une méthode générale permettant de métamorphoser des personnages modélisés à l'aide de surfaces implicites à squelettes en cours d'animaton et/ou déformation. Les objets sont représentés par un modèle intermédiaire générique dont les paramètres évoluent indépendamment au cours du temps. L'animorphose, mixage d'animation, de déformation et de métamorphose, est associée à un modèle intermédiaire générique contrôlable interactivement ou de manière semi-automatique. Un contrôle de haut niveau est possible grâce à l'animorphose de Bézier qui généralise l'animorphose entre plusieurs formes de contrôle.

Keywords: implicit surfaces, animation, metamorphosis.

Abstract: Bien que de nombreuses études sur l'animation et la métamorphose existent dans la littérature, le mélange d'animation et de métamorphose n'a jamais été abordé à notre connaissance. Nous nous proposons ici de définir l'animorphose, c'est-à-dire le mixage d'animation et de métamorphose, pour certaines catégories de surfaces implicites. Notre objectif est d'intégrer le concept d'animorphose au BlobTree. Ce modèle définit une surface implicite à l'aide d'un arbre de construction hiérarchique.
Dans ce cadre, notre contribution est triple. Nous avons développé de nouvelles primitives à squelettes complexes (volumes, courbes splines) afin d'en accroître les possibilités de modélisation. Nous présentons un système d'animation cinématique pouvant être étendu à un système à validation dynamique. Il repose sur l'interpolation entre les instants clefs des paramètres caractérisant les composantes du BlobTree. Enfin l'animorphose est définie par un modèle intermédiaire générique et l'interpolation des paramètres de définition des composantes appariées dans le graphe de correspondance défini par l'utilisateur.
Le contrôle de l'animation, comme les corrections de trajectoire, élément primordial nécessaire à l'obtention d'effets spéciaux convaincants, est réalisé simplement par le déplacement, l'insertion ou la suppression de points de contrôle dans l'interpolation. Un contrôle de haut niveau est présenté grâce à l'animorphose de Bézier qui généralise l'animorphose entre plusieurs formes de contrôle.

Keywords: implicit surfaces, animation, metamorphosis.