Dade wrote: ↑Sat Aug 15, 2020 10:23 am
Yes, more "directional" are the materials (i.e. glossy, specular, etc.) a more bias introduces the cache. PGI fallback more often to normal path tracing in order to reduce the bias.
Matte is the less "directional" of all materials and PGI doesn't introduce bias at all so it can use cache entries as often as it can (aside corner, again, to avoid artifacts).
So...for everything than matte there isn't any shortcut to a fast free-noisy solution like we have with matte mats?
It's a pity because it's very rare to have a scene with just matte materials, and the worst case is when you have most of the image covered by matte materials and some key elements with glossy ones. In this way you have to wait a lot of time (and samples) to clean just the glossy mats
I've done a comparison on a test scene I'm doing...and the difference is big...and consider that the image on the left (walls matte mats and furniture with glossy mats) needs at least 3-4 time the image on the right (just matte mats) and it's still noisy on the glossy parts.
Dade wrote: ↑Sat Aug 15, 2020 10:23 am
Yes, if you raise the PGI glossiness threshold over the material roughness (or you rise the material roughness over the threshold).
This is quite a not smart solution because you could have several glossy materials with different roughness values and also because if you control the roughness with textures, it's difficult to find the right final roughness value. At the end you'll spend a lot of time on test renderings to find the right balance...with complex scene where you have several glossy mats...well..it's not doable.
I hope you'll introduce some ways to improve render speed on this kind of materials.