基于非均匀B样条小波的NURBS曲面光顺  

NURBS Surface Fairing Based on Non-uniform B-spline Multi-resolution Wavelet Decomposition

作　　者：李奇敏[1] 柯映林[2] 何玉林[1] 

机构地区：[1]重庆大学,重庆400044 [2]浙江大学,杭州310027

出　　处：《中国机械工程》2007年第5期577-582,共6页China Mechanical Engineering

基　　金：重庆大学高层次人才科研启动基金资助项目(0903005104967)

摘　　要：将非均匀B样条小波分解方法用于曲面光顺。通过整体光顺度量确定曲面整体光顺的方向,进而通过曲面整体小波分解实现曲面的整体光顺;通过曲面在节点对处的局部光顺度量,确定要光顺的节点及方向,然后用最小区域算法实现曲面的局部光顺;给出了一种由用户交互指定光顺区域的区域光顺方法;用细节部分的再次分解控制曲面的光顺误差;通过施加约束解决光顺前后曲面边界位置和切矢不变的问题;对于计算的稳定性及可能出现的奇异情况给出了论述。这些光顺算法在浙江大学开发的反求工程CAD软件RE-SOFT中的实际应用效果表明,基于非均匀B样条小波分解的NURBS曲面光顺算法能够有效地去除曲面上的坏点,改善曲面的品质。Non-uniform B-spline multi-resolution wavelet decomposition was applied to the fairing of NURBS surface. The global fairing direction was determined by global faring measure of two parametrical directions, and then the global fairing of surface was realized through global decom- position of surface. Local fairing of surface was realized by minimal region algorithm, in which the bad knot and fairing direction was determined by local fairing measure of knot pair. A region fairing method was proposed, in which the fairing region was specified by the user interactively. The problem of position and tangent preserving of end point was solved by adding constraints. The robustness of wavelet decomposition and possible singularity were presented. The application result in RE-SOFT, a reverse engineering software developed by Zhejiang University, shows that the fairing algorithm based on non-uniform B-spline wavelets decomposition can efficiently remove the bad points on surface and improve quality of the surface.

关 键 词：小波 非均匀B样条曲面 光顺 光顺度量 

分 类 号：TP391[自动化与计算机技术—计算机应用技术]