David Cazier

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Many data structures are available for the representation and manipulation of meshes. In the context of algorithms that need to traverse local neighborhoods, topological structures are of particular interest. Many such existing structures are specialized for the representation of objects of a given dimension like surface or volume meshes. Many of them find(More)
We address in this paper the problem of the data structures used for the representation and the manipulation of multiresolution subdivision surfaces. The classically used data structures are based on quadtrees, straightforwardly derived from the nested hierarchy of faces generated by the subdivision schemes. Nevertheless, these structures have some(More)
Many representation schemes have been proposed to deal with non-manifold and mixed dimensionalities objects. A majority of those models are based on incidence graphs and although they provide efficient ways to query topological adjacencies, they suffer two major drawbacks: redundancy in the storage of topological entities and relationships, and the lack of(More)
Locating the internal structures of an organ is a critical aspect of many surgical procedures. Minimally invasive surgery, associated with augmented reality techniques, offers the potential to visualize inner structures, allowing for improved analysis, depth perception or for supporting planning and decision systems. Most of the current methods dealing with(More)
Virtual cutting of deformable objects is at the core of many applications in interactive simulation and especially in computational medicine. The ability to simulate surgical cuts, dissection, soft tissue tearing or micro-fractures is essential for augmenting the capabilities of existing or future simulation systems. To support such features, we combine a(More)
Realistic simulation of crowds is an important issue for the production of virtual worlds for games, entertainment or architectural and urban planning. Difficult issues need to be addressed such as collision avoidance and the handling of dynamic environments. In this paper, we present a unified structure for the simulation of complex urban environments. We(More)
The geometric refinements of 2D and 3D subdivisions are basic operations in geometric programming. They consist in partitioning their cells, until no intersection exists between them and in achieving their topological restructuring. We present new methods to formalize their design. We present an algebraic specification of the operators needed to handle the(More)
Collision detection in geometrically complex scenes is crucial in physical simulations and real time applications. Works based on spatial hierarchical structures have been proposed for years. If correct performances are obtained for static scenes, these approaches show some limitations when the complexity of the scene increases and particularly in case of(More)
Current methods dealing with non-rigid augmented reality only provide an augmented view when the topology of the tracked object is not modified, which is an important limitation. In this paper we solve this shortcoming by introducing a method for physics-based non-rigid augmented reality. Singularities caused by topological changes are detected by analyzing(More)