高质量快速百分比邻近滤波软影算法  

High Quality and Efficient Percentage Closer Soft Shadows

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》2014年第3期329-338,共10页Journal of Computer-Aided Design & Computer Graphics

基　　金：国家自然科学基金(61173128;61170138;60933007);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：在基于实时绘制的各种应用中,百分比邻近滤波软影算法可以高效地绘制视觉真实的软影效果.针对该算法中存在的3个主要问题,提出一种具有高质量阴影滤波的高效百分比邻近滤波软影算法.首先通过多尺度阴影图数据结构精简搜索区域,提升了遮挡物深度估计的正确性;然后使用基于GPU的线性四叉树遍历算法快速计算遮挡物平均深度,节省了大量的纹理采样开销,大大提高算法效率;最后采用光滑阴影滤波算法,解决了百分比邻近滤波算法中的走样瑕疵.将文中算法集成入多阴影图算法框架可以取得接近物理真实的软影效果.实验结果表明,该算法在效率和阴影质量方面均取得了显著的进步.Percentage closer soft shadow （PCSS） is a prevalent algorithm in real-time applications due to its simplicity and efficiency.But soft shadows generated via PCSS often suffer from artifacts due to incorrect occluder estimation,meanwhile its performance drops down dramatically when the size of light source becomes large.Furthermore,the shadows also suffer from severe aliasing artifacts.In this paper we propose an efficient percentage closer soft shadow algorithm with smooth filtering.Multi-scale shadow maps are adopted to estimate search area accurately and calculate average blocker depth efficiently using a linear GPU quad-tree traversal algorithm.Finally,smooth soft shadows are generated via a high quality filtering algorithm.By integrating the proposed algorithm into a multiview shadow mapping framework,high quality shadows can be generated which approaches to the ground truth.The experimental results show that the proposed algorithm can generate smoother soft shadows with higher frame rates compared to the previous techniques.

关 键 词：阴影图 软影 反走样 百分比邻近滤波软影 

分 类 号：TP391[自动化与计算机技术—计算机应用技术]