GGX = fireflies.

[Vizioen]

I'm having a lot of fireflies lately and they're always related to the GGX BRDF. Doesn't matter if it's an interior or an exterior or VraySun or HDRI lighting. The only way of solving it is switching to blinn/ward. Any solutions or known problems? I never touch clamp or subpixelmapping and i'm not planning to either. I switched off probabilistic lights though there's only one lightsource in the latest testing scenes didn't touch the max ray intensity thingy (still at 20 default).



edit: as some side info; the example above had been rendering for a whopping 17 hours on progressive 1 - 100 with default noise thresholds

[viscorbel]

I'm having the same issue quite often - fireflies on reflective ggx shaders at glancing angles.

Progressive + ggx in those cases seems impossible to render cleanly, as those fireflies don't really go away, they just kind of move around with more passes.
With adaptive + high min shading rate they can be cleaned up in more reasonable time.

[Crush]

Same here, although I didn't have time to investigate properly. I tend to use progressive just to setup my scene and then switch to adaptive for finals anyway, so it's rather an annoyance.

[Vizioen]

Same here, although I didn't have time to investigate properly. I tend to use progressive just to setup my scene and then switch to adaptive for finals anyway, so it's rather an annoyance.

So it might be a combination of GGX with the progressive. Hopefully Vlado can fix this, as I like progressive a lot, saves me time setting up adaptive.

[kagemaru]

For us it hasn't been an issue with progressive per se since we always use adaptive and i got this problem a lot.
Unfortunately our usual timeline doesn't involve much time on optimizing and investigating, and we are quite unorganized so i can't afford to try and reduce these issues every time. In several cases the only option was to increase secondary rays to a crazy amount just to try and clean them up (and sometimes not completely) while everything else was fine.
I kind of banned the use of ggx here and it's a pity.

We talked about this here

[LudvikKoutny]

I have the same problem even with progressive sampler. I use GGX for all my materials as I can't stand the cheap fake look of Blinn BRDF. Disabling of reflective caustics has no effect on the fireflies what so ever. They mostly occur on surfaces that are mapped with glossiness map which varies glossiness value around the top of the range (between 0.8 to 1.0). Would be really good to improve GGX sampling a bit so it can become primary BRDF and Blinn can drown in the history of unsuccessful inferior BRDFs.