Real-time indirect illumination by virtual planar area lights

Abstract This paper presents a method called Virtual Planar Area Lights (VPALs) to generate single-bounce diffuse-to-diffuse indirect illumination for dynamic scenes and light sources. Different from the VPLs (Virtual Point Lights) based methods, which extract point lights from RSM (Reflective Shadow Map), our method fits RSM by many planar regions which will be directly used as virtual light sources to generate the indirect illumination. In order to reduce the illumination errors introduced by plane fitting, we propose several strategies, including an illumination-guided plane fitting algorithm, a normal correction factor and a virtual light sources reuse strategy. Our experimental results indicate that our method can achieve a good balance between the rendering performance and quality. Compared with traditional light culling and clustering methods, the rendering consumption of our algorithm is reduced by at least 67 % with the similar RMSE (Root Mean Squared Error).