Deformations de surfaces complexes: techniques de haut niveau pour la modelisation et l'animation

SIGLEINIST T 73527 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Layered Deformable Models with Implicit Surfaces

Several challenging problems in the animation of deformable objects can be solved by combining existing models with implicit surfaces. The latter are used as an extra layer which coats any kind of structure that moves and deforms over time. Implicit surfaces detect collisions, model local deformations, and transmit response forces to the inner structures. They also control the variations of the object's volume. We present several applications from the animation of organic shapes to the simulation of soft inelastic substances that can separate into smaller pieces or fuse into larger ones. R esum e Plusieurs problemes difficiles dans le domaine de l'animation d'objets deformables peuvent etre resolus en combinant les modeles existants avec des surfaces implicites. Utilisees pour habiller une structure en mouvement, ces dernieres detectent les collisions, modelisent les deformations locales qui en resultent, et transmettent les forces de reponse a la structure interne. Elles peuvent eg..

Local Deformations for Animation of Implicit Surfaces

Implicit surfaces are well suited to modelling organic forms that consist of an internal skeleton and deformable flesh smoothly blended around it. An implicit surface can represent such an object's geometric "skin" that deforms according to the motion of the skeleton. We propose a new, simple and e#cient method for calculating local deformations to be applied to implicit surfaces during collisions with other objects or between di#erent parts of one object. We discuss applications of this method to deformable object simulation, character animation and interactive sculpture. 1 Introduction Of growing popularity in computer graphics, implicit surfaces [16] are particularly well suited to modelling organic forms [11, 2, 14] since they generate a smooth surface around skeletons of arbitrary geometry and topology. Animation of such forms is well established [1, 6, 8] and is normally performed in a layered model, in which the internal skeleton is used to specify the global behaviour of an ob..

Simulating landslides for natural disaster prevention

The simulation of landslide hazards is a key point in the prevention of natural disasters, since it enables to compute risk maps and helps to design protection works. We present a 3D simulator that handles both rock-falls and mud-flows. The terrain model is built from geological and vegetation maps, superimposed on a DEM. Since the exact elevation of the terrain is unknown at the rock’s scale, the simulator uses a series of stochastic simulations, where low scale geometry is slightly randomized at each impact, to compute an envelop of risk areas. Computations are optimized using an implicit formulation of surfaces and a space-time adaptive algorithm for animating the particle system that represents the mud flow.

Introduction to Modelling and Animation Using Implicit Surfaces

International audienceno abstrac

Introduction to Modelling and Animation Using Implicit Surfaces

International audienceno abstrac

Virtual Sculpture

Short PapersInternational audienceWe propose here a sculpture metaphor for rapid shape prototyping. This metaphor makes the underlying surface description transparent for the user, enabling him to focus only on the shape being modeled. Our approach is based on implicit surfaces defined as iso-surfaces over a discrete field

Resolution Adaptive Volume Sculpting

Special Issue on Volume ModellingInternational audienceWe propose a sculpture metaphor based on a multiresolution volumetric representation. It allows the user to model both precise and coarse features while maintaining interactive updates and display rates. The modelled surface is an iso-surface of a scalar-field, which is sampled on an adaptive hierarchical grid that dynamically subdivides or undivides itself. Field modifications are transparent to the user: The user feels as if he were directly interacting with the surface via a tool that either adds or removes "material". Meanwhile, the tool modifies the scalar field around the surface, its size and shape automatically guiding the underlying grid subdivision. In order to give an interactive feedback whatever the tool's size, tools are applied in an adaptive way, the grid being always updated from coarse to fine levels. This maintains interactive rates even for large tool-sizes. It also enables the user to continuously apply a tool, with an immediate coarse-scale feedback of the multiple actions being provided. A dynamic Level-Of-Detail (LOD) mechanism ensures that the iso-surface is displayed at interactive rates regardless of the zoom value; surface elements, generated and stored at each level of resolution, are displayed depending on their size on the screen. The system may switch to a coarser surface display during user actions, thus always insuring interactive visual feedback. Two applications illustrate the use of this system: Firstly, complex shapes with both coarse and fine features can be sculpted from scratch. Secondly, we show that the system can be used to edit models that have been converted from a mesh representation

Sculpture virtuelle

National audienceNous présentons ici une métaphore de sculpture destinée au prototypage rapide de formes 3D. La surface sculptée correspond à l'iso-valeur d'un champ potentiel scalaire échantillonné spatiallement. L'utilisateur peut déposer de la matière où il le désire dans l'espace puis itérativement affiner sa forme grâce à un outil servant à déposer, retirer, peindre ou lisser de la matière, comme déjà proposé dans les approches précédentes. Nous étendons la forme des outils disponibles à des formes libres générées par l'utilisateur. Nous proposons aussi une méthode permettant d'utiliser l'outil pour déformer localement et/ou faire des empreintes sur une forme existante. Nous présentons enfin deux implémentations permettant de stocker ce champ potentiel discret. Leurs performances et limitations sont discutées dans l'article