Joint Source and Channel Coding of Meshgrid-represented Objects

MESHGRID is a scalable 3D object representation method which is part of MPEG-4 AFX. This paper proposes a new approach for optimized protection of MESHGRID-represented objects against transmission errors occurring over error-prone channels. An unequal error protection approach is followed, to cope with the different error-sensitivity levels characterizing the various resolution and quality layers produced by MESHGRID. The protection level to be employed for each layer is determined by solving a joint source and channel coding problem. The Linfinite distortion metric is used, and its superiority over the classical L-2 norm is proven. In this context, a novel fast algorithm for solving the optimization problem is conceived. The proposed joint source and channel coding approach offers resilience against transmission errors, enables a real-time implementation, and preserves all the scalability features and animation capabilities that characterize MESHGRID. Index Terms — 3D graphics, MESHGRID, error resilient coding, JSCC, unequal error protection, L-infinite coding.