Comparison of light sampling techniques and their combinations in the Veach's scene
Comparison of different combinations of standard light and BSDF sampling techniques. Power heuristic is almost optimal in this scene. See Section 8.4 in the main paper for discussion.
Compared variants
| Variant | Used shortcut |
|---|
| BSDF | B |
| Light | L |
| BSDF + Light, balance heuristic | B+L bal |
| BSDF + Light, power heuristic | B+L pow |
| BSDF + Light, optimal weights - direct estimator | B+L opt-dir |
| BSDF + Light, optimal weights - progressive etimator with update step U | B+L opt-prog-U |
Equal-time comparison
Number of iterations is set so each variant takes approximately 20 s to render.
| Variant |
Time [s] |
Iterations |
MSE |
Speedup (to B+L pow) |
| B |
19.89 |
31 |
5.52E-002 |
0.01 |
| L |
19.52 |
21 |
6.10E-004 |
0.66 |
| B+L bal |
19.26 |
12 |
4.23E-004 |
0.95 |
| B+L pow |
19.43 |
12 |
4.02E-004 |
1.00 |
| B+L opt-dir |
20.13 |
12 |
3.94E-004 |
1.02 |
| B+L opt-prog-1 |
19.96 |
9 |
5.22E-004 |
0.77 |
| B+L opt-prog-2 |
19.39 |
10 |
4.66E-004 |
0.86 |
| B+L opt-prog-3 |
20.62 |
11 |
4.28E-004 |
0.94 |
| B+L opt-prog-4 |
20.01 |
11 |
4.29E-004 |
0.94 |
| B+L opt-prog-5 |
19.98 |
11 |
4.34E-004 |
0.92 |
| B+L opt-prog-6 |
19.37 |
11 |
4.37E-004 |
0.92 |
| B+L opt-prog-7 |
19.93 |
11 |
4.41E-004 |
0.91 |
| B+L opt-prog-8 |
19.44 |
11 |
4.43E-004 |
0.91 |
| B+L opt-prog-9 |
19.41 |
11 |
4.48E-004 |
0.90 |
| B+L opt-prog-10 |
21.27 |
12 |
4.14E-004 |
0.97 |
Equal-sample comparison
Each variant renders 10 iterations, i.e. draws 10 samples per light per technique per pixel. For the single-technique variants results with the same total number of samples per light per pixel (i.e. 20) are also included.
| Variant |
Time [s] |
Iterations |
MSE |
Overhead (to B+L pow) |
Improvement (to B+L pow) |
| B |
6.41 |
10 |
5.85E-002 |
-60.12% |
0.01 |
| B 20 |
12.79 |
20 |
5.33E-002 |
-20.50% |
0.01 |
| L |
9.28 |
10 |
1.02E-003 |
-42.30% |
0.47 |
| L 20 |
18.53 |
20 |
6.27E-004 |
15.23% |
0.78 |
| B+L bal |
16.01 |
10 |
5.14E-004 |
-0.44% |
0.95 |
| B+L pow |
16.08 |
10 |
4.86E-004 |
0.00% |
1.00 |
| B+L opt-dir |
16.89 |
10 |
4.75E-004 |
5.02% |
1.02 |
| B+L opt-prog-1 |
22.23 |
10 |
4.70E-004 |
38.24% |
1.03 |
| B+L opt-prog-2 |
19.44 |
10 |
4.66E-004 |
20.88% |
1.04 |
| B+L opt-prog-3 |
18.82 |
10 |
4.70E-004 |
17.04% |
1.03 |
| B+L opt-prog-4 |
18.45 |
10 |
4.72E-004 |
14.71% |
1.03 |
| B+L opt-prog-5 |
17.80 |
10 |
4.78E-004 |
10.67% |
1.02 |
| B+L opt-prog-6 |
17.70 |
10 |
4.83E-004 |
10.07% |
1.01 |
| B+L opt-prog-7 |
17.67 |
10 |
4.86E-004 |
9.88% |
1.00 |
| B+L opt-prog-8 |
17.75 |
10 |
4.94E-004 |
10.33% |
0.98 |
| B+L opt-prog-9 |
17.70 |
10 |
5.00E-004 |
10.06% |
0.97 |
| B+L opt-prog-10 |
17.08 |
10 |
5.05E-004 |
6.19% |
0.96 |
