多层阴影图轮廓边背投软影算法  

Multi-Layered Soft Shadow Mapping via Contour Back-Projection

作　　者：沈笠[1] 杨宝光[1] 冯结青[1] 

机构地区：[1]浙江大学CAD&CG国家重点实验室,杭州310058

出　　处：《计算机辅助设计与图形学学报》2013年第9期1265-1274,共10页Journal of Computer-Aided Design & Computer Graphics

基　　金：国家自然科学基金(61173128;61170138);国家"九七三"重点基础研究发展计划项目(2009CB320800);教育部新世纪优秀人才支持计划(NCET-10-0728)

摘　　要：在场景深度和物体分布复杂时,针对轮廓边背投软影算法中的可见性因子计算存在误差,从而导致过阴影和光渗等绘制瑕疵的问题,提出一种基于掩码的多层阴影图遮挡物轮廓边背投软影算法.该算法通过计算光源掩码的深度复杂函数获得更准确的可见性因子,解决了轮廓边背投软影算法中存在的过阴影问题;将光源掩码计算与多层阴影图结合以解决光渗问题,最终生成更高质量的光滑软影.实验结果表明,在保证绘制效率的前提下,文中算法可以产生更为准确、真实的软影效果.Among various soft shadow mapping techniques, the back-projection one can generate high- quality soft shadows effects efficiently. The shadow map is adopted to represent the geometries of the scene discretely. The method evaluates the visibility factor of each pixel by back-projecting occluder contour edges extracted from the shadow map to the area light. However it suffers from shadow over estimation and light leaking artifacts for the scenes with complex depth and geometry distributions. In this paper we propose a mask based occluder contour edge back-projecting soft shadow method. By computing the depth complexity function of every sample-mask on the area light, we can successfully remove the shadow over estimation artifact. By incorporating it into multi-layered shadow mapping, we can then overcome the light leaking artifact. The experimental results show that the proposed method can generate more realistic and accurate soft shadows with high efficiency.

关 键 词：阴影图 软影 背投 深度剥离 

分 类 号：TP391[自动化与计算机技术—计算机应用技术]