LightCluster - Clustering Lights to Accelerate Shadow Computation

Abstract

In this paper, we propose a method to reduce the amount of shadow maps required for rendering shadows in scenes with many lights. Our idea is to use the spatial relationship of lights to find clusters and replace the lights of a cluster with a single area light. We use a soft shadow algorithm for area lights to approximate the shadows for the clusters. By carefully placing the cluster centers, we can minimize the errors in the shadows. While the clustering only adds a small overhead in the worst case, it can efficiently reduce the number of shadow maps. Thus, in many cases the resulting error in shadows is acceptable compared to the increase in rendering performance.