3D modeling for multimedia applications

Image coding standards usually focus on storing and transmitting signals efficiently, in a frame based approach. The coming MPEG-4 standard [1] adds a new challenge, namely bringing new services to image communication users. It moves towards representing a scene as a composition of audiovisual objects rather than "just" a collection of pixels. MPEG-4 objects can be captured naturally by one (or more) camera(s), or be synthesized by a computer. They can be 2D or 3D. Their composition is called Synthetic / Natural Hybrid Coding (SNHC). The MPEG-4 SNHC standard is being extended to support human face and body representation. Face and body animation parameters (FAPs and BAPs) have been defined. 1.2 MPEG-4 core experiment on hand animation INT / SIM is involved with EPFL / LIG in validating the BAPs exchange format [2]. Hand animation sequences in the MPEG-4 format have been produced independently by each partner, and replayed successfully by the other (figure 1) [3, 4]. 2. 3D object registration INT / SIM contributes to a France Telecom / CNET project on scene representation from image sequences. Other partners are INRIA / SYNTIM and INRIA / TEMIS. This project aims at restituting a 3D representation of a dynamic scene from an uncalibrated video image sequence. The scene is assumed to be composed of objects for which a generic deformable model is available, surrounded by an unknown environment. The unknown fixed areas can be reconstructed using projective techniques. Known objects are detected and identified by an indexation based method applied on the moving areas [5].