Approximate Ambient Occlusion For Trees

Natural scenes contain large amounts of geometry, such as hun-dreds of thousands or even millions of tree leaves and grass blades. Subtle lighting effects present in such environments usually include a significant amount of occlusion effects and lighting variation. These effects are important for realistic renderings of such natural environments; however, plausible lighting and full global illumina-tion computation come at prohibitive costs especially for interactive viewing. As a solution to this problem, we present a simple ap-proximation to integrated visibility over a hemisphere (ambient oc-clusion) that allows interactive rendering of complex and dynamic scenes. Based on a set of simple assumptions, we show that our method allows the rendering of plausible variation in lighting at modest additional computation and little or no precomputation, for complex and dynamic scenes.