difficult to clean-up bokeh

[Fat Tony]

Hello, am having hard time clean up bokeh effect. Trying AA sampling tried shading sampling. threshold is on 0.01. This one is bit bitmap but same result i get from circular default one. Also i tried to go higher on min samples but didnt really help.

Thanks for suggestions

[Svetlozar Draganov]

Aren't there any improvement with with higher AA settings?
How high did you go, can you share some settings along the result they gave?
If there is no difference even with extreme AA settings it could be a bug which will have to investigate.
Would it be possible to send us stripped down version of the scen for investigation.

[Fat Tony]

Yes, there were no improvement. I tried all the options. ADV sampling on divide shading rate 2 all the way to 36 with, threshold from 0.01 to .002. didnt help.
Clamping in linear burn value of 0.6 helped a little but didn't remove them, and anyways that is making image flat. Ray intensity values no change at all. Caustics off, no change

I have solved it by separating reflections into new HDRI dome light. The setup is that i have one HDRI with gamma 1, that affects diffuse and specular (i kept specular cause i didn't want to loose highlights), and second duplicate HDRI that affects reflections only (and cast shadows) with gamma 1.3 and bit higher render mult to reach the same brightness in refl. This setup removed the fireflies almost completely.

It is not ideal situation but fixed my problem. Therefore the issue was strong small highlights were giving this badly done bokeh.

[^Lele^]

Your best bet, instead of arbitrarily gammaing, clamping, and soft compressing, would be to stick to LWF for shaders and lights.
Bokehs are difficult to resolve by definition, and yet with the right energies at play, i have recently found no particular issue with them, albeit of course they'll require high camera sampling.
If, however, the tiny glint contains a lot more energy that would have any right to, and it's small enough to be hard to find in the first place, what you'd get would be precisely that: uncleanable bokehs.
For this scene it may be too late, but try and make a conscious effort to stay truly linear throughout with your next one needing bokehs, and you'll see the difference.

[Fat Tony]

i almost never go out of linear workflow, even tried to clean it up in post by various denoising plugins but nothing really work. This one was difficult one, in night scene and such i rarely have an issue, but in here it was just the case of 1-2 pixels that went extremely bright and this caused the issue. Found workaround, not happy about ditching LWF in this case but result is fine. 1 out of 100 is ok to do like this

[jironomo]

Hey Lele, what do you mean by 'truly linear'? Not using color mapping burn? And using low albedo shaders and real life values for lights?

[^Lele^]

Hey Lele, what do you mean by 'truly linear'? Not using color mapping burn? And using low albedo shaders and real life values for lights?

Yes, exactly.
Any deviation from real-life values ought to be accidental, or reserved to post.
That's my take, anyways.

[Morbid Angel]

hey FatTony, what are your exact dmc settings? I mean min / max value?

[Fat Tony]

hey FatTony, what are your exact dmc settings? I mean min / max value?

Default from 3.6 min-max 1-24 but i went all the way up to 4-24 in orther to try to clean up the DOF more, which it did but didn't help on fireflies

[Morbid Angel]

yeah can you show the shading rate for this render? also can you post a part of this scene? I suspect the fireflies can be from really small light sources, or parts of hdr which are impossible to trace indirectly.

[thanulee]

Hey Dmitry, ye its probably some overbright pixels in the hdr, but how do u address this issue? I ve noticed too many hdrs have similar problems in my renders. thanks

[Morbid Angel]

well you have to think about it: a really small tiny bright dot like a sun put on a huge 360 panorama would result in some bright speckle noise. Its because when tracing rays from camera to object and outwards (or indirectly) will require a very large number of samples to get precise replication of the given pixel. Where as in real world there is no resolution in any reflection or anything like that. So you would have to compensate for this. Paint out the tiny pixels from hdr. Replace them with something that's more traceable like vray lights etc etc.

[^Lele^]

What Dmitry says, plus if you can do with it, make those reflections less sharp, with a bit less IoR, with lower overall reflection intensity, and so on.
Particularly if you use assets from 3rd party libraries, the risk of using non-EP, or badly energy preserving shaders (ie. non-extinguishing) is higher than if you did stuff yourself.

[Fat Tony]

What Dmitry says, plus if you can do with it, make those reflections less sharp, with a bit less IoR, with lower overall reflection intensity, and so on.
Particularly if you use assets from 3rd party libraries, the risk of using non-EP, or badly energy preserving shaders (ie. non-extinguishing) is higher than if you did stuff yourself.

shaders were done from scratch, so no issue there. there were cheats ofc, it is solved the way i mentioned above, just it took some uncomfortable compromises.

[jstrob]

Hi fat Tony I would try this: go in Color mapping, set Sub-pixel mapping on and clamp output to 5 or 8.