Realistic Soft Shadows by Penumbra-Wedges Blending

Vincent Forest, Loïc Barthe and Mathias Paulin

Eurographics Graphics Hardware 2006, Vienna, Austria.

[bibtex] [pdf] [video1] [video2] [video3] [video4]

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 taking the advantage of the penumbra-wedges and solving the "non-overlapping" limitation. We first store the light occlusion position. Then we use this information to detect the areas where penumbrae are overlapping and we perform a realistic penumbra blending.

Half-life² scene 01 Half-life² scene 02

Our algorithm applied on a scene composed of 6662 polygons. This scene is based on the models and materials of Half-life². Objects and textures copyright Valve Corporation: used with permission.

Penumbra-wedges algorithm Penumbrae blending by a probabilistic approach Our algorithm 1024-sample shadows

Simple penumbrae blending comparison - From left to right: standard penumbra-wedges algorithm [SIG03], penumbrae blending by the probabilistic approach [GH03], Our algorithm and a reference image using 1024-sample shadows.

Penumbra-wedges algorithm Our algorithm 1024-sample shadows

Complex penumbrae blending comparison - From left to right: standard penumbra-wedges algorithm [SIG03], Our algorithm and a reference image using 1024-sample shadows.

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