Efficient Methods for Ambient Lighting

1
Efficient Methods for Ambient Lighting

• Tamás Umenhoffer
• Balázs Tóth
• László Szirmay-Kalos

2
Overview

• Ambient illumination
• Illumination model
• Implementation
• Results

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Previous work

• Obscurances method Zhukov et al.
• Ambient occlusion Hayden
• Spectral obscurances Mendez et al.
• Screen space ao Mittring

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New Illumination Modell
Factorization
Participating media approximation
Substituting the fuzzy measure
Local approximation
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Comparison
albedo
Ambient transfer W
Classic AO
New approximation
GI reference
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Containment test

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

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

• Importance sampling
• Sample generation (offline)

N
r1
T
B
1.
2.
3.

• Sampling (online, post processing)

Depth map
N
x
9
Noise reduction
Sampled neighborhood

• Interleaved sampling
• Per pixel rotation of the samples
• Per pixel set of samples
• Periodical structure
• Additional filtering required
• Blurry contours

Periodic pattern
8 samples
8 samples alternating
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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
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Results
Reference
Crytek (260 FPS)
Containment test (300 FPS)
R3
R9
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Results
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Video
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Thank you for attention!