一种三维实体模型表面法线计算方法研究  

Research of Calculating Method for Surface Normal Line of 3D-Entity Model

作　　者：程磊[1] 刘海艳[1] 

机构地区：[1]沈阳理工大学信息科学与工程学院,辽宁沈阳110168

出　　处：《沈阳理工大学学报》2009年第4期24-27,共4页Journal of Shenyang Ligong University

摘　　要：介绍了实体模型的几何造型原理,研究了生成模型表面顶点法线的两种常规方法.针对常规方法对具有棱角的模型表面表现不准确的问题,提出了棱边分裂法,计算得到所有两个相邻三角形夹角大于阈值的共享棱边,为相关的每个顶点增加新的法线向量.具体可由棱边之间或与边界之间所夹的三角形通过常规方法计算得到,使棱边两侧的表面能正确地进行光照计算,真实反映了模型的几何特征,提高了绘制的真实感.In this paper, the principle of geometric modeling of the entity model is introduced. Two usual methods for obtaining the vertex normal line on the model surface are studied. The usual methods have a disadvantage on expressing the model surface with some sharp corners. So the edge splitting method is brought out, by calculating to gain the sharing edge with the angles bigger than a threshold of two adjacent triangles. New normal lines for each vertex on the edge are added, and it could be worked out by the triangles between sharp edges and boundary lines with usual methods. It makes the lighting calculation for surfaces at each side of the edge correctly. The geometrical features of the model can be shown in truth; and the third dimension of the rendering can be also improved.

关 键 词：实体模型 法线 棱边分裂法 

分 类 号：TP391[自动化与计算机技术—计算机应用技术]