Model-based motion compensated compression for synthetic animations

Advances in rendering hardware and software over the last decade have led to a steady increase in the popularity of computer-generated animations. This is especially apparent in the entertainment industry as synthetic animations are being used in films, CD-ROMs and video games. The scientific community also makes heavy use of synthetic animations in visualizing data sets. A problem with synthetic animations is that, like video sequences, they contain a large amount of data. In order to store long sequences or send them across a network, the data must be compressed. One approach to performing motion-compensated compression on synthetic animations is to treat them as video sequences and use standard image-based compression algorithms such as MPEG. Alternatively, we can take advantage of information used in rendering the animation to guide the motion estimation algorithm and hence perform better compression. Such information includes the 3D world space movements of the objects in the scene and the projection transformations from world space into screen space. We examine how to use this motion information to perform fast, accurate block-based motion-estimation and design a closed loop compression system like MPEG