Efficient Methods for Ambient Lighting Tamás Umenhoffer Balázs Tóth László Szirmay-Kalos

Overview Ambient illumination Illumination model Implementation Results

Previous work Obscurances method [Zhukov et al.] Ambient occlusion [Hayden] Spectral obscurances [Mendez et al.] Screen space ao [Mittring]

New Illumination Modell Factorization Participating media approximation Substituting the fuzzy measure Local approximation

Comparison albedo Classic AO New approximationGI reference Ambient transfer W

Containment test Implicit surface f(p)=0 Height field z = h(x, y) Displacement map Z-buffer x z

Containment test x Inner parts Outer parts I(p) membership function A B R C

Solution Importance sampling –Sample generation (offline) r= –Sampling (online, post processing) T B N N x Depth map

Noise reduction Interleaved sampling –Per pixel rotation of the samples Per pixel set of samples Periodical structure –Additional filtering required –Blurry contours 8 samples 8 samples alternating Periodic pattern Sampled neighborhood

False silhouette removal Depth difference in the Z buffer –Ambient transfer function fails –Fake shadow on the background object Images without and with silhouette edge elimination

Results R=3 R=9 Crytek (260 FPS) Reference Containment test (300 FPS)

Results

Video

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