Actually, I was looking for an optimal openCL render for the completed wooden room.
First, I used random sampler also in combination with denoiser or post processing without getting a useful result. Then I switched through all available samplers in luxcorerender addon looking for an appropriate solution. The images are impressions on the way to a clean version of the image.
GPU Tile path rendered the scene quite fast but the image was noisy
- Wooden Room 250 Samples GPU Tile Path clamped 10000
or if clamped with lower value
- Wooden Room 250 Samples GPU Tile Path clamped 100
the ashtray made from glass got dark and table's colors faded.
Random and Sobol showed similar results.
GPU Metropolis looked different from the first few samples and even more promising with 250 Samples then I increased the number of samples.
- Wooden Room 1000 Samples GPU Metropolis not clamped
- Wooden Room 1000 Samples GPU Metropolis clamped 2859
Already a quite clean image but clamping also lead to a dark glass.
Intermediate conclusion: Looks like openCL won't lead to a final version for this room scene.
Let's give Sobol on CPU BiDir a chance.
- Wooden Room 72 Samples, CPU BiDir, sobol not clamped
The ceiling looks more realistic if compared to path render but I stopped here wiht 72 samples because of my experiences with Sobol on path.
Again Metropolis proved its strenghts for this kind of scene. The only issue left has been the ashtray on the table.
Thanks to Metropolis' parameter maximum consecutive rejects I finally got what I was looking for.
- Wooden Room 821 Samples, CPU BiDir, metropolis max cons. rej. 16384, not clamped
I've noticed earlier there is an issue with ashtray object. It looks so easy to be modelled but it is a nasty one to get it nicely smoothed.
This and because table was over exposed (render starts with fitting exposure but gets over exposed with incresing number of samples) I started a second render. On my machine it took almost 11 hours to get the required 1000 samples, less are a halfway house.
- Wooden Room 10h48m 1000 Samples CPU BiDir Metropolis
(The ashtray needs a further update. I know smoking is bad, but I like the test.)
Conclusion: Metropolis is the choice for difficult illumination in a room.
EDIT: Impressions during rendrering.
OpenCL tile path, clamped
https://youtu.be/-gwMqE-Eoyc
OpenCL, path, metropolis, clamped
https://youtu.be/OzDfO2sk7Kk
OpenCL, path, metropolis
https://youtu.be/9vOYWnespRQ
CPU, BiDir, random
https://youtu.be/TphfSHVZI3A
CPU, BiDir, metropolis
https://youtu.be/eaF9Ld5Z9r8