Encoding Animated Meshes in Local Coordinates

For various 3D Animation processing, representing mesh geometry in local rather the world coordinate systems is very useful. One can investigate the representation of vertex locations relative to a local coordinate frame (LCF) in the compression of dynamic 3D meshes. Unlike the world coordinates, which scatter in a wide range and show non linear behavior of the vertices, the local coordinates exhibit a large clustering behavior of the vertex over time. This property is very useful for exploiting a large coherence over the vertex trajectory and between neighboring vertices. In this paper, we discuss the use of the LCF in mesh encoding and we introduce a new and simple predictive scheme for single-rate compression for animated meshes. Our geometry encoding strategy is based on a region growing encoding order and only the delta vectors between original and predicted locations are encoded in a local coordinate system, which splits into two tangential and one normal components. Our approach is simple, efficient and well suited for real time applications.