一种改进的虚拟平面区域光源实时软阴影绘制算法
An Improved Real-Time Soft Shadow Drawing Algorithm Based on Virtual Planar Area Light Source
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摘要: 实时无走样/无漏光软阴影绘制有利于提高场景渲染的真实性. 为解决虚拟平面区域光源全局光照模型在阴影渲染部分的走样现象和平面区域光源(PALs)数量递增导致实时渲染帧率下降的问题, 首先引入高斯方差阴影贴图(GVSM)生成无走样软阴影; 然后提出改进的GVSM算法, 通过指数变换增强物体的深度比值, 生成无漏光软阴影; 最后结合重要性采样策略, 动态采样具有主要光照贡献的PALs, 提升实时渲染帧率. 在Sponza和Gallery等场景的实验表明, 使用相同数量的PALs进行渲染, 所提算法在实现柔和无走样/无漏光阴影绘制的同时, 达到10%~30%的渲染帧率提升.Abstract: Real-time soft shadow drawing with no artifacts/leakage can help to improve the reality of scene rendering. In order to eliminate aliasing of shadow rendering in the global illumination model of virtual planar area light sources (PALs) and solve the problem of frame rate decreasing of real-time rendering due to the in-creasing number of PALs, the Gaussian variance shadow mapping (GVSM) is introduced to generate soft shadow without aliasing, an improved GVSM algorithm is proposed to enhance the depth ratio of objects through exponential transformation to generate soft shadow without light leakage. An importance sampling strategy is incorporated to dynamically sample PALs that have the major lighting contributions to improve the real-time rendering frame rate. Experiments in Sponza and Gallery scenes show that the proposed algo-rithm not only realizes soft shadow drawing without aliasing and light leakage, but also achieves a 10%-30% frame rate improvement in rendering with the same number of PALs.