Realistic Soft Shadows by Penumbra-Wedges Blending

Abstract

Recent real-time shadow generation techniques try to provide shadows with realistic penumbrae. However, most techniques are whether non-physically based or too simplified to produce convicing results. The penumbra-wedges algorithm is a physical approach based on the assumption that penumbrae are non-overlapping. In this paper, we propose an algorithm that takes the advantages of the penumbra-wedges method but solves the "non-overlapping" limitation. We first compute the light occlusion regions per fragment. Then we use this information to detect the areas where penumbrae are overlapping and we perform a realistic penumbra blending.