Dividing Cubes算法生成的物体表面的法向量方向的光顺操作  

Smoothing Operation of Normal Directions on Object Surface Produced by Dividing Cubes

作　　者：吴良武[1] 欧宗瑛[1] 秦绪佳[1] 侯建华[1,2] 

机构地区：[1]大连理工大学机械工程学院CAD&CG研究所 [2]大连现代高技术发展有限公司大连116021

出　　处：《计算机辅助设计与图形学学报》2001年第12期1137-1141,共5页Journal of Computer-Aided Design & Computer Graphics

基　　金：国家"八六三"高技术研究发展计划项目 ( 86 3-30 6 -ZD13-0 3-6 )资助

摘　　要：在用 Dividing Cubes算法提取的边界体素所构造的物体表面上 ,可能会存在法向量方向突变 ,使得物体表面光照图显示粗糙 .文中提出了一种改进的邻域加权平均法 ,对物体表面的法向量方向进行光顺处理 ,光顺操作只在相关边界体素间进行 ,并且对有多个等值面交汇的边界体素将不进行光顺操作 ,以避免模糊位于多个区域处的边界和保持物体表面光照图的细节 .为避免在屏幕上产生孔洞 ,用光线投射法显示物体表面 .文中所采用的光顺操作可以消除物体表面的法向量方向突变 ,使物体表面光照图光滑细腻 .最后 ,给出一个医学图像的测试实例 .There might exist abrupt changes of the normal directions on a voxel object surface generated by Dividing Cubes, which would cause the shading image of the object look coarse and rough. A modified neighborhood weighted average approach was proposed in this paper for smoothing the normal directions on the voxel object surface. To avoid blurring the boundaries among several regions and preserve the details of the shading image of the object surface, the smoothing operation was only applied to those boundary voxels which were relevant, while the boundary voxels which had several isosurfaces were not smoothed. The algorithm of Ray Casting was used to display the object surface to avoid producing missing holes on the screen. The modified approach can eliminate those abrupt changes of the normal directions on the voxel object surface and improve the display quality. A verified example of a medical volume data is presented.

关 键 词：光顺操作 DividingCubes算法 领域加权平均 孔洞 计算机图形学 医学图像 

分 类 号：TP391.41[自动化与计算机技术—计算机应用技术] R319[自动化与计算机技术—计算机科学与技术]