摘要
对非均匀有理B样条(NURBS)的权因子作了分析研究。首先,阐述了NURBS曲面权因子的几何意义,说明了权因子是有关4点的交比,并分析了权因子的极限性质以及零权因子对曲面形状的影响;其次,就曲面上一点在控制顶点方向与任意方向移动这两种情况,给出了曲面形状调整时权因子的计算公式;最后,给出了曲面权因子调整的应用算例。
In this paper,the weighted factor of the Non-Uniform Rational B-Sample(NURBS) is analyzed and researched. Firstly,the geometric sense of the weighted factor of the NURBS curved surface is described,thus,indicating that the weighted factor is the cross-ratios for 4 related points. The limiting character of weighted factor and the effect of the zero weighted factor on the curved surface shape are analyzed. Secondly,the computation formula for the weighted factor in adjusting the curved surface shape is suggested in the two cases of one point on the curved surface moving towards the direction of controlling top point or the random direction. Finally,an application example of changing the weighted curved surface is given.
出处
《西安理工大学学报》
CAS
2004年第2期154-158,共5页
Journal of Xi'an University of Technology
关键词
CAGD
NURBS
曲面
曲面修形
权因子
CAGD
NURBS
curved surface
curved surface modification
weighted factor
