Ambient Occlusion for Particles
• Encode global information in textures for use during rendering
Computes level of obscurances
Results
• Movie 1 (show off some data sets)
• Movie 2 (use with direct lighting and shadows)
Precomputation Time and Memory
• Using 20 R14K processors on an SGI Origin 3800 (muse.sci.utah.edu). Textures were 16x16 with 49 samples per texel.
955,000
66 min.
233 MB
952,755
261 min.
232 MB
543,088
33 min.
132 MB
7,157,720
12 hours
1,747 MB
Fireball Bullet Foam
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.
Direct lighting
DL with Textures
Textures w/o DL
Fireball 6 16.43 f/s 14.97 f/s 16.75 f/s
Fireball 11 10.55 f/s 9.59 f/s 10.16 f/s
Cylinder 6 13.32 f/s 12.15 f/s 13.37 f/s
Cylinder 22
11.71 f/s 10.94 f/s 11.75 f/s
Bullet 2 28.17 f/s 25.59 f/s 28.79 f/s
Bullet 12 28.76 f/s 25.71 f/s 28.41 f/s
ImagesDirect Lighting
onlyDirect lighting with ambient occlusion
textures
Ambient occlusion textures only
Cylinder 22 Bullet 6 Fireball 11
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.
Direct lighting
DL with Textures
Textures w/o DL
Fireball 6 16.43 f/s 14.97 f/s 16.75 f/s
Fireball 11 10.55 f/s 9.59 f/s 10.16 f/s
Cylinder 6 13.32 f/s 12.15 f/s 13.37 f/s
Cylinder 22
11.71 f/s 10.94 f/s 11.75 f/s
Bullet 2 28.17 f/s 25.59 f/s 28.79 f/s
Bullet 12 28.76 f/s 25.71 f/s 28.41 f/s
Ingredients for Edges
• Image buffer • Depth buffer• Edge detection kernel• Threshold for zero
crossings
-1 -1 -1
-1 8 -1
-1 -1 -1Laplacian kernel
Movies
• Movie 1 (Varying the threshold and changing the view point and field of view)
• Movie 2 (Time varying data)
Performance
Without With Slowdown
A 18.00 f/s 17.52 f/s 2.63%
B 2.250 f/s 2.222 f/s 1.25%
C 2.259 f/s 2.225 f/s 1.51%
D 1.185 f/s 1.172 f/s 1.05%
E 2.720 f/s 2.665 f/s 2.02%
A
B C
D E
Silhouette and Ambient Occlusion Examples