紧凑的累进网格数据格式及其网络传输

以基于三角形折叠的三角网格简化算法为基础，给出一种支持三维模型数据累进传榆的数据存储格式，并讨论了该格式在网络环境下的数据压缩问题。该方法首先记录网格简化过程中网格局部的连通性（Connectivity）修改信息，并通过对原始网格中的顶点和面片进行重新排序．生成了由基网格和累进记录序列组成的累进网格数据格式；通过对累进数据格式中的连通性信息进行哈夫曼编码，以及顶点数据的区段离散化，实现了网格拓扑信息的无损压缩和可以预测精度的几何信息压缩。结果显示，利用紧缩的累进数据格式，可自由地实现任意三角网格模型连续分辨的变进或变出，并且相关编，解码过程简单、快速，模型数据的压缩比较高。该数据格式及其数据压缩方法可用于三维模型的压缩存储和网络传输。

Compact Data Format for Progressive Meshes and Its Data Transmission over Internet

A novel data format for storage and transmission of progressive mesh (PM) was proposed based on the mesh simplification method, which recursively collapsed triangles in dense mesh. The method first simplifies mesh surface and records related changes of local connectivity of the mesh, and then reorders the sequences of vertices and facets of the mesh to generate compact progressive data format, which consists of a base mesh with two lists of vertex coordinates and progressive facet records respectively. By employing Huffmann coding scheme and discretization method in three certain intervals, progressive records of PM and coordinates of the vertices in the mesh can be compressed dramatically. Experiences show that the algorithm can obtain higher compression ratios than previous methods, and by using the method, 3D mesh models not only can be refined from the simplest base mesh to its complex version, but also can be simplified from the complex version to the simplest one at any stage during rendering process, rapidly and smoothly.