An Improved Real-Time Soft Shadow Drawing Algorithm Based on Virtual Planar Area Light Source

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.