Intermediate shadow maps for interactive many-light rendering

We present an efficient method for computing shadows for many light sources (e.g., 1024). Our work is based on the observation that conventional shadow mapping becomes redundant as the number of lights increases. First, we sample the scene with a constant number of depth images (e.g., 10), which we call intermediate shadow maps. Then the shadow map for each light is approximated by rendering triangles reconstructed from the intermediate shadow maps. The cost of rendering these triangles is much smaller than rendering the original geometry of a complex scene. The algorithm supports fully dynamic scenes. Our results show that our method can produce soft shadows comparable to those obtained by conventional shadow mapping for each light source or by ray tracing, but at a higher frame rate.