Strange overbrighted pixels (not fireflies)

[frodopytlicek]

Hello,
does anyone have any idea what can couse this overbrighted pixels? According to what I know they are not fireflies. They appears across whole image randomly on each frame.

This doesn't help:
- subpixel mapping ON
- reflection/refraction/glossy effects OFF
- filter gi OFF
- global illumination OFF
- full light evaluation ON
- max ray intensity any value
- adaptivity clamp any value

Only thing that makes them dissappear is progressive rendering, but I cannot use it in production.

[Philip Shounev]

Hello,

Since the above mentioned settings did not help, except for switching to progressive sampler, would it be possible to share your scene to philip.shounev@chaos.com for troubleshooting ?

[frodopytlicek]

It's super heavy and under NDA, I'm not sure how to send it:/ I found out its also connected to min shading rate but I have to set it to 24 at least to make them dissaperar and this makes rendering super long

[frodopytlicek]

So I dig deep and found out it was caused by strange data comming from texture pluged in fog folor of refractive material. Clamping the texture with output node solve the problem. It was this texture from cgtextures https://www.textures.com/download/cr...pbr0146/133204 which surprised me because their textures are great quality. But maybe you will be able to reproduce it.

[Philip Shounev]

Does this happen if you use another texture or is it just for this particular one ? I still can't reproduce it in a newly created scene so additional details would be of use. F.e. what's the lighting in the scene, what is the translucency type for the refractive material, reflection / refraction values, thickness of the refractive object ?

[frodopytlicek]

I did some tests and it did not occur with other textures (at least not on the same place or frame). Material looks like this and its icy ball cca 170m in diameter with a lot of spikes and icicles, so quite heavy refractive object.

[Joelaff]

I think I have also seen some flickering that was from an unclamped Fog map. Is there any reason not to clamp this internally?

(And spit out a warning in the log... Fog map clamped to 0-1.0 if it exceeds this)

[frodopytlicek]

At least some log warnig would be usefull.

[Vipera]

When I render explosions via VRayVolumeGrid created in PhoenixFD most of the time I see random overbrighted pixels on object surfaces near explosion. But if I disable GI generation for VRayVolumeGrid then they disappear. Maybe this not your case but could give you a clue.

[georgi.zhekov]

When I render explosions via VRayVolumeGrid created in PhoenixFD most of the time I see random overbrighted pixels on object surfaces near explosion. But if I disable GI generation for VRayVolumeGrid then they disappear. Maybe this not your case but could give you a clue.

Can you send us the scene for this one so that we can check it? You can attach it here if possible or send it over through support.chaos.com (submit a request at top right) with a link to this thread.

Thanks!

[Vipera]

Can you send us the scene for this one so that we can check it? You can attach it here if possible or send it over through support.chaos.com (submit a request at top right) with a link to this thread.

Thanks!

I was not able to attach file in this thread because of page error. I have submitted it via support ticket (Request #292694).