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