In this test we will compare Geo Light sampling technology in 3Delight OSL, Arnold and RenderMan. We will use a test with a geometric area light that is composed of a relatively large number of faces. The test should allow us to find out how the algorithm in general noise level and local adaptivity. We will use 2 different cameras to test these two aspects.
The Scene
The test scene allows for procedural generation of floating area lights using the "Tubes Per Step" PaintEffects attribute.
The scene is designed to procedurally generate a number of area lights floating on top of a "city".
- Only diffuse reflectors. The original test scene had a diffuse+specular surface but that generated a considerable amount of additional noise in Arnold. Since we want to concentrate on light sampling here, we decided to go for a simpler setup.
- We will disable any adaptive sampling so to make sure we have very close ray-counts.
- We will use only direct lighting to estiamte the geometric area light contribution. In the statistics files for each renderer, one can see that we have only one path lenght.
- All Renders are done in Maya 2016.
Methodoloy
The idea here is to test the quality of the different light samplers.
Arnold
| Samples | 2 (1.23) | 4 (4.91) | 8 (19.64) | 16 (78.56) | 32 (314.29) | 64 (1257.18) |
|---|---|---|---|---|---|---|
| Time | 1s | 2s | 6s | 21s | 1:21 | 8:12 |
| Shadow Rays | 0.678 M | 3.26 M | 10.8 M | 43.4 M | 173.6 M | 694.5 M |
| RMSE | 0.15699 | 0.100115 | 0.0501787 | 0.0242515 | 0.0117413 | 0.00693426 |
3Delight
| Samples | 2 | 4 | 8 | 16 | 32 | 64 | 128 | 256 |
|---|---|---|---|---|---|---|---|---|
| Time | 5.72s | 8s | 12.82 s | 22.18 s | 40.92 s | 86.91 | 165.69 s | 302.98 |
| Shadow Rays | 2.45 M | 3.13 M | 4.51 M | 7.27 M | 12.78 M | 23.8 M | 45.88 M | 90.1 M |
| RMSE | 0.0933142 | 0.0658266 | 0.0441248 | 0.0290439 | 0.0185575 | 0.0117566 | 0.00752546 | 0.00449892 |
Preliminary Conclusions (for self, re-wording needed)
- 3Delight generates light samples that are significantly better than both Arnold and Prman.
- 3Delight is slower to to generate these samples. Meaning that for draft renders Arnold/PrMan will seem faster. For final renders 3Delight becomes increasingly faster.
- Using so much less samples also makes 3Delight faster when shading is more expensive
- RenderMan seems to have difficulties in sampling.
- Arnold has a solid albeit O(N^2) algorithm (vs O(N) in 3Delight) and compensates to a certain degree with very fast light sampler.
- When combining BRDFs, 3Delight is even less noisy.