一种基于Phong模型的体绘制明暗度快速算法

Accelerated Volume Rendering Using a Fast Shading Algorithm

高效、精确地完成三维医学图像数据 (如 CT、MRI等 )的体积显示 ,有助于医生对感兴趣的病灶部分或器官形成直观的认识 ,从而做出诊断或手术计划 .针对体绘制的一个重要环节——明暗度的处理 ,提出了一种基于球面三角化的快速算法 ,其速度较传统的明暗度处理方法快近 2倍 ,同时大大节省了中间数据的存储量 ,有利于在微机上实现 .误差分析和实验结果表明 ,所提出的快速算法绘制质量与传统方法没有明显差异 。

This paper discussed an important step in volume rendering——shading, using a fast algorithm based on a unit sphere segmentation. The main idea in this algorithm is that, first, do triangulation on a unit sphere in order to have enough points which are chosen from each triangle to represent all directions in 3D space. Second, substitute all directional vectors on a triangle by the points chosen on it. Third, establish a lookup table to do shading calculation by Phong model. The new shading method is nearly twice as fast as the traditional one; while the precision is almost the same as the traditional one. The result shows it is a feasible method.