Chapter 8. Summed-Area Variance Shadow Maps

Andrew Lauritzen University of Waterloo

In this chapter, we discuss shadow-map filtering and soft shadows. We review the variance shadow-mapping algorithm and explain how it can help solve many common shadowmapping problems. We also present a simple but effective technique for significantly reducing the light-bleeding artifacts associated with variance shadow maps (VSMs).

Finally, we introduce a real-time shadowing algorithm based on VSMs and summedarea tables (SATs). We achieve efficient computation of shadow contributions for arbitrary rectangular filter regions, which makes summed-area variance shadow mapping (SAVSM) an ideal algorithm for soft shadows without aliasing.

Introduction

Shadow mapping (

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