Ambient Occlusion for Particles

1
Ambient Occlusion for Particles

• Encode global information in textures for use
  during rendering

2
Computes level of obscurances
3
Results

• Movie 1 (show off some data sets)
• Movie 2 (use with direct lighting and shadows)

4
Precomputation Time and Memory
Bullet
Fireball
Foam
543,088 33 min. 132 MB
955,000 66 min. 233 MB
952,755 261 min. 232 MB
7,157,720 12 hours 1,747 MB

• Using 20 R14K processors on an SGI Origin 3800
  (muse.sci.utah.edu). Textures were 16x16 with 49
  samples per texel.

5
Impact on Performance

• 10 slower than direct lighting alone.
• However, using only the ambient occlusion values
  can yield as good as or better performance than
  direct lighting alone.

6
Images
Direct Lighting only
Direct lighting with ambient occlusion textures
Ambient occlusion textures only
Cylinder 22
Bullet 6
Fireball 11
7
Impact on Performance

• 10 slower than direct lighting alone.
• However, using only the ambient occlusion values
  can yield as good as or better performance than
  direct lighting alone.

8
Ingredients for Edges

• Image buffer
• Depth buffer
• Edge detection kernel
• Threshold for zero crossings

Laplacian kernel
9
Movies

• Movie 1 (Varying the threshold and changing the
  view point and field of view)
• Movie 2 (Time varying data)

10
Performance
A
B
C
D
E
11
Silhouette and Ambient Occlusion Examples