Progressive coding of 3-D graphic models
Based on state-of-the-art graphic-simplification techniques and progressive image-coding schemes, we propose a new hierarchical three-dimensional graphic-compression scheme in this research. This scheme progressively compresses an arbitrary polygonal mesh into a single bitstream. Along the encoding process, every output bit contributes to the reduction of coding distortion, and the contribution of bits decreases according to their order of position in the bitstream. At the receiver end, the decoder can stop at any point while giving a reconstruction of the original model with the best rate-distortion tradeoff. A series of models of continuous varying resolution can thus be constructed from the single bitstream. This property, which is referred to as the embedding property since the coding of a coarser model is embedded in the coding of a finer model, can be widely used in robust error control, progressive transmission and display, level-of-detail control, etc. It is demonstrated by experiments that an acceptable quality level can be achieved at a compression ratio of 20 to 1 for several test graphic models.