Adaptive Depth Bias for Shadow Maps Hang Dou 4, Yajie Yan 4, Ethan Kerzner 2, Zeng Dai 1, Chris Wyman 3 University of Iowa 1, SCI Institute 2, NVIDIA 3 Washington University in St. Louis 4

Introduction False self-shadowing or shadow acne : no bias appropriate bias :

Introduction Cause of false self-shadowing

Introduction Our work: remove false shadowing with less false unshadowing Constant BiasOur Method

Introduction Related Work Constant Slope ScaleDual Depth

Observation

Adaptive Bias 1.Lift the fragment just above the false shadow caster inside the corresponding shadow map texel. 1.Find the false shadow caster or compute adaptive offset. 2.Move the fragment just above the false shadow caster with an adaptive epsilon value. 2. AdaptiveBias = AdaptiveOffset + AdaptiveEpsilon

Compute the adaptive offset Traditional Shadow Map

Apply to paraboloid shadow map Paraboloid Shadow Map

Apply to voxelized shadow volume Voxelized Shadow Volume

Compute the Adaptive Epsilon Depth Compression in OpenGL

Compute the Adaptive Epsilon

Results Traditional Shadow Map Constant Slope Scale Our Dual Depth

Results Paraboloid Shadow Map Constant Slope Scale

Results Paraboloid Shadow Map OurDual Depth

Results Voxelized Shadow Volume ConstantOur

Timing

Limitation When shadow map resolution gets too low. When light source gets too far away.

Conclusion We compute an adaptive depth bias to eliminate the shadow acne. We implement our method for traditional shadow map, paraboloid shadow map and voxelized shadow volume. ConstantAdaptive

Questions?