| Summary: | 博士 === 中原大學 === 電子工程研究所 === 93 === Abstract
Single-rate connectivity compression approaches for 3D models can be divided into edge-based and vertex-based algorithms. Edgebreaker is an edge-based approach, whereas the valence-driven approach is vertex-based. Both approaches use split operation to separate the 3D model into two components, that raise some bottlenecks for spending increased overheads to record the displacement, or an extra operator is needed for identifying the branch. The Edgebreaker is either multiple pass traversals or operate in reverse order. Multiple pass traversals take a long time to execute. Operation in reverse order should work only off line since its decompression order follows the reverse order of the compression. The valence-driven method requires an extra pass to calculate the valence of vertices when the triangular mesh does not have vertex degree information. To eradicate these restrictions, this study presents three edge-based single-resolution compression algorithms for managing triangular mesh connectivity. The proposed algorithms encode and decode 3D models straightforwardly with sequential single traversal.
The proposed Algorithm I provides using the J operator to skip to the next edge of the active boundary; the method need not split overhead. By using Q operator, two triangles are encoded to improve compression ratio. The proposed Algorithm II investigates spatial locality to minimize costs in split operations. Meanwhile, some simplification rules are proposed by considering geometric characteristics which ignore the last triangle when a split occurs. The proposed Algorithm III combines Algorithm I and Algorithm II, the method improves not only the compression ratio but also the execution time.
An adaptive arithmetic coder is applied to the proposed algorithms, to increase the compression ratio. The experimental results indicate that an excellent compression ratio can be obtained, and the average compression ratio associated with the proposed algorithms are better than that associated with the valence-driven and Edgebreaker methods. The curve of compression ratios is near the entropy curve of the proposed algorithms. The proposed algorithms fixed the number of operators and their value distribution by only considering the context between operators in optimizing the compression ratio.
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