基于轮廓边拟合的软影映射算法

摘要

Rendering high quality shadows with large penumbra in real-time is a challenging problem. In this paper, we propose a new edge extracting method with a new data structure to attack this problem and provide an efficient and practical technique for soft shadow generation. First, a multi-pass method to fit edge lines in a fixed size block containing edge pixels is presented, and then a hierarchical texture map saving these lines entitled hierarchical edge map (HEM) is employed. Finally the visibility is computed by back-projecting these lines in HEM onto the 2D light source domain to generate realistic soft shadow. The rendering performance is greatly improved, while keeping the soft shadow quality.%针对实时软影映射算法在绘制大面积光源时绘制效率不高的问题,提出一种基于轮廓边拟合的快速软影映射算法.该算法在场景阴影映射图中的固定尺寸的块内拟合轮廓边直线,并用一种层次化的数据结构来保存拟合的轮廓边直线；再利用反投影轮廓边直线的方法快速地计算着色点的可见性,生成真实的软影效果.实验结果表明,与现有的算法相比,文中算法在不显著降低软影质量的基础上有效地提高了绘制效率.