Distorted shadow mapping

Abstract

In this paper, a novel algorithm named Distorted Shadow Maps (DSMs) is proposed to generate high-quality hard shadows in real-time. The method focuses on addressing the shadow aliasing caused by different sample distribution between light and camera space. Inspired by the fact that such aliasing occurs in the depth-discontinuous regions of shadow map, in DSMs, a sample redistribution mechanism is designed to enlarge the geometric shadow silhouette regions by shrinking the regions that are completely in light or in shadows. Consequently, more texels in the shadow map are covered by the geometric silhouettes, indicating that silhouettes get more samples. The experimental results show that the jagged edges of hard shadows are reduced by the DSMs algorithm.