LuxCoreRender Forums

Dade wrote: ↑Tue Jun 08, 2021 1:58 pm

kintuX wrote: ↑Tue Jun 08, 2021 11:20 am But I realized what the issue was/is. Basically I was checking BiDir with newly added caustics cahe (SDS paths) on "pool tester scene" where discrapency showed. I found it is caused by single scatter Specular material. And of course BiDir engine shows it brighter since it traces both ways.

I'm not sure to understand what you mean with "single scatter Specular material": something like mirror (single scatter) Vs. glass (2x scatter, reflect and transmit) ?

Anyway it sounds like a bug in BiDir with some very specific type of path being rendered 2 times, I have to check.

What I meant is single scattering microfacetted BSDF model which is the main cause of dark glass (& my usual suspect).
Since I haven't noticed any change in GI brightness with Photon depths of 8, 12, 25 & 64, I imagined Water (Glass surface) is blocking GI contribution to & from pool floor which then only contributes a single bounce using Path engine on the backwall & ceiling in shadow (note I may be totally wrong). Why I made Water shadow transparent and got brighter Indirect Light.

Is the scene using rough or clear glass?

B.Y.O.B. wrote: ↑Tue Jun 08, 2021 10:16 pm Is the scene using rough or clear glass?

Clear.
And it's just a surface, w/o Volume.

Then single/multiscattering is irrelevant in this case, since it is only a concept for rough materials.