The Research of Real-Time Shadow Rendering Algorithm of Virtual Scenes

Shadow scenes by shadow mapping has long suffered from the problem of under-sampling artifacts due to too little shadow map resolution leading to so-called perspective and projection aliasing. On this issue, we present a new practical real-time shadow mapping algorithm. Firstly we sample the scene from the eye-point on the GPU to get the needed shadow map resolution in different parts of the scene. Then we process the resulting data on the CPU and construct a hierarchical grid structure. Finally we traverse it in quad-tree fashion, shadowing the scene with shadow map pages where needed. The results show that shadow mapping algorithm based on quad-tree is capable of shadowing large scenes by virtually increasing the resolution of the whole shadow map beyond the GPU hardware limit.