Zerotree Coding of Subdivision Wavelet Coefficients in Dynamic Time-Varying Meshes

We propose a complete system to enable progressive coding with quality scalability of the mesh geometry, in MPEG's state-of-the-art Video-based Dynamic Mesh Coding (V-DMC) framework. In particular, we propose an alternative method for encoding the subdivision wavelet coefficients in V-DMC, using a zerotree coding approach that works directly in the native 3D mesh space. This allows us to identify parent-child relationships amongst the wavelet coefficients across different subdivision levels, which can be used to achieve an efficient and versatile coding mechanism. We demonstrate that, given a starting base mesh, a target subdivision surface and a desired maximum number of zerotree passes, our system produces an elegant and visually attractive lossy-to-lossless mesh geometry reconstruction with no further user intervention. Moreover, lossless coefficient encoding with our approach requires nearly the same bitrate as the default displacement coding methods in V-DMC. Yet, our approach provides several quality resolution levels embedded in the same bitstream, while the current V-DMC solutions encode a single quality level only. To the best of our knowledge, this is the first time that a zerotree-based method has been proposed and demonstrated to work for the compression of dynamic time-varying meshes, and the first time that an embedded quality-scalable approach has been used in the V-DMC framework.