局部包络片控制误差简化三角网格模型

Triangulated Surface Model Simplification Using Part Offset-Patches As Errors Tolerance

利用内外包络控制三角网格模型简化误差是一种可行的方法.但构造整个模型的内外包络需要花费较多的时间,且每次简化操作时也会进行大量重复的三角形相交检测,使算法效率下降.针对这些问题,本文提出了局部包络片控制误差的思想,即每次简化操作仅利用相关部分的包络来控制误差.算法采用三角形收缩操作简化模型,当原始模型上的一个三角形被选中,并尝试进行收缩操作时,先构造其对应的局部包络片;在该三角形收缩后,原来与之相邻的三角形将发生形变,若这些形变后的三角形位于局部包络片之间,则认为此次三角形收缩操作可以接受,否则予以取消.实验结果表明,局部包络片保持了良好的误差控制效果,且由于构造简单,很少发生自交现象,减少了三角形相交检测次数,提高了计算效率.

Errors tolerance is a very important problem in simplifying triangulated surface model. An effective method to find tolerance errors is to use the whole inner and outer envelopes of a triangulated surface model. However, there will be many complicated operations to compute intersections between triangulations when constructing the whole inner and outer envelope of a triangulated surface model, which will lower the algorithm efficiency. We introduce a novel algorithm for simplifying triangulated surfaces model using the part offset-patches as errors tolerance, which are constructed by offsetting a part of triangles on the surface and can also be regarded as a small part of the whole inner and outer envelopes. Because the part offset-patches are much smaller than the whole inner and outer envelopes of a triangulated surface model, our algorithm is both simple and easy to implement. We also have developed a software system to test our algorithm. Experiment results show that expense of our algorithm is much less than that in the algorithm using the whole inner and outer envelope of a triangulated surface model and it keeps higher similarity between simplified model and original one.