Pierre Kraemer

CGoGN: N-dimensional Meshes with Combinatorial Maps

Summary. 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 their roots in combinatorial maps, a mathematical model for the representation of the topology of the subdivision of objects, which is consistently defined in any dimension. We present a practical implementation of combinatorial maps that competes with modern state-of-the-art data structures in terms of efficiency, memory footprint and usability. Among other benefits, developers can use a single consistent library to manipulate objects of various dimensions.

A unified structure for crowd simulation

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 crowds in complex urban environments. We propose a topological multiresolution model supporting different levels of details, allowing efficient proximity querying and compatible with real‐time rendering and hierarchical path planning. A fine exploitation of the multiscale aspect of the underlying model allows to achieve the same efficiency as the fastest existing methods. The generality of the approach allows the simulation to be executed on any two manifold, and the unified approach eases the handling of dynamic environments. Copyright

X-maps: An Efficient Model for Non-manifold Modeling

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 a uniform representation of those entities that leads to the development of large sets of intricate topological operators. As regards to manifold meshes -- and specifically triangular ones -- compact and efficient models are known for twenty years. Ordered topological models like combinatorial maps or half edges based data structures are widely studied and used. We propose a new representation scheme -- the extended maps or

Simplification of meshes with digitized radiance

X\!

CPH: A Compact Representation for Hierarchical Meshes Generated by Primal Refinement

-maps -- that enhances those models to deal with non-manifold objects and mixed dimensionalities. We exhibit properties that allows an adaptive implementation of the cells and thus ensures that

Multiresolution half-edges

X\!

Visual Quality Assessment of 3D Models: On the Influence of Light-Material Interaction

-maps scale well in case of large surface areas or manifold pieces. We show that the storage requirements for

Deformable polygonal agents in crowd simulation

X\!

A general and efficient representation for multiresolution meshes: application to quad/triangle subdivision

-maps is strongly reduced compared to the radial edge and similar structures and also present optimizations in case of triangular or tetrahedral non-manifold meshes.

Un modèle générique pour la manipulation de maillages multirésolution

View-dependent surface color of virtual objects can be represented by outgoing radiance of the surface. In this paper we tackle the processing of outgoing radiance stored as a vertex attribute of triangle meshes. Data resulting from an acquisition process can be very large and computationally intensive to render. We show that when reducing the global memory footprint of such acquired objects, smartly reducing the spatial resolution is an effective strategy for overall appearance preservation. Whereas state-of-the-art simplification processes only consider scalar or vectorial attributes, we conversely consider radiance functions defined on the surface for which we derive a metric. For this purpose, several tools are introduced like coherent radiance function interpolation, gradient computation, and distance measurements. Both synthetic and acquired examples illustrate the benefit and the relevance of this radiance-aware simplification process.