Motion analysis methods in Computer Vision usually deal with tracking rigid, articulated or deformable objects in a scene, but little or no work has been done on the analysis of 3-D deformable surface, such as cloth, the surface of a liquid, or the surface of a plastic solid subject to various deformations. With the recent availability of high-resolution and high-dynamic cameras, it is now possible to perceive very subtle changes in the images, and bring up information about the 3-D deformations of these surfaces, especially when several viewpoints of the surface are available.

There are a few methods specialized in the reconstruction of continuous surfaces from several viewpoints, which take into account constraints on the regularity of the observed surface, such as PDE-based stereo methods. However, 3-D reconstruction data of a surface at each time instant does not contain information about the 3-D motion of each individual point on the surface. What we get is a 2-D manifold in a 3-D space (i.e. a surface reconstruction), whereas we also may want a 3-D vector field (the motion field) defined on that manifold.

A testbed application for these new methods we are developping is the ACI Masse de données GEOLSTEREO, which started in September 2004. Within this project, we will develop methods based on stereoscopy to extract the 3D motion field of the surface of a wax model under different constraints or displacements. The results on these small-scale model is then used to predict the evolution of geological processes. The surface is globally continuous, but discontinuities may appear because of landslides or breaches. These discontinuities must also be detected and precisely measured. The method we are considering to solve this problem uses a continuous 3-D mesh which is deformed through time, and where edges can be broken if discontinuities appear.