Revectorization-based shadow mapping

Abstract

Real-time rendering of high-quality, anti-aliased shadows is a challenging problem in shadow mapping. Filtering the shadow map reduces aliasing, but artifacts are still visible for low-resolution shadow maps or small kernel sizes. Moreover, the existing techniques suffer from light leaking artifacts. Shadow silhouette recovery reduces perspective aliasing at the cost of large memory footprint and high computational overhead for the shadow mapping. In this paper, we reduce aliasing with the revectorization-based shadow mapping. To effectively reduce the perspective aliasing, we revectorize shadow boundaries based on their discontinuity directions. Then, we take advantage of the discontinuity space to filter the shadow silhouettes, further suppressing the remaining artifacts. To control the filter kernel size, we incorporate percentage-closer filtering into the algorithm. This enables us to reduce jagged shadow boundaries, to simulate penumbra and to provide high-quality screen-space anti-aliasing. Compared to previous techniques, we show that shadow revectorization produces less artifacts, consumes less memory and offers real-time performance. The results show that our solution can be used in games and other applications in which real-time, high-quality shadows are desirable.