Bit allocation for joint source and channel coding of progressively compressed 3-D models

This work presents a joint source and channel coding method for transmission of progressively compressed three-dimensional (3-D) models where the bit budget is allocated optimally. The proposed system uses the Compressed Progressive Mesh (CPM) algorithm to produce a hierarchical bitstream representing different levels of detail (LODs). In addition to optimizing the transmitted bitstream with respect to the channel characteristics, we also choose the optimum combination of quantization and tessellation to maximize the expected decoded model quality. That is, given a 3-D mesh, a total bit budget (B) and a channel packet-loss rate (P/sub LR/), we determine the optimum combination of: 1) the geometry coordinates quantizer step size (l-bit); 2) the number of transmitted batches (L); 3) the total number of channel coding bits (C); and 4) the distribution of these channel coding bits among the transmitted levels (C/sub L/). Experimental results show that, with our unequal error protection approach that uses the proposed bit-allocation algorithm, the decoded model quality degrades more gracefully (compared to either no error protection or equal error protection methods) as the packet-loss rate increases.