一种trimmed NURBS曲面的裁剪方法

A TRIMMING METHOD FOR TRIMMED NURBS SURFACE

所研究trimmed NURBS曲面的裁剪方法分三步完成裁剪算法。其主要特点是将所有trimmed NURBS曲面与裁剪轮廓面的交线都转为封闭环,从而可以统一的方式处理各类裁剪问题。实验结果表明,该算法可方便地解决目前一些曲面造型系统对已裁剪的内部和外部边界无法再裁剪等问题,亦可应用于一般形式的trimmed参数曲面的裁剪操作。

This paper presents a trimming method consisting of three steps.All operations are car- ryed out in surface's parametric space.The data structure of a surface is based on loop, edge,point entities.The major advantages of the method is that intersection algorithm and trimming operation is independent of the definition of surface and all kinds of trimming opera tion can be deal with in an unified approach.Experimental results show that the method is feasible and obviously simplifies the trimming operation problem.The method may be direct- ly used in a NURBS surface modeling system being developed.