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Caustics on Car Paint doesn't work
Posted: Thu Dec 02, 2021 1:00 pm
by AcidNemesis
So I've added both Light-Tracing and Caustics cache to be sure, and after multiple attempts it still doesn't work. I won't be able to attach the file as it is too big but I'll bring an image of the render and the caustics pass.
https://imgur.com/a/4woZKW0
https://imgur.com/a/90ZvSIP
Edit : "[img]" doesn't work :/
Re: Caustics on Car Paint doesn't work
Posted: Thu Dec 02, 2021 3:32 pm
by Dade
AcidNemesis wrote: ↑Thu Dec 02, 2021 1:00 pm
So I've added both Light-Tracing and Caustics cache to be sure, and after multiple attempts it still doesn't work. I won't be able to attach the file as it is too big but I'll bring an image of the render and the caustics pass.
Car paint is a glossy material and glossy material caustics are rendered only if you set the light tracing/cache glossiness threshold over the one used by the material (otherwise the material is excluded). If you post a scene of a cube over a plain with the carpaint material you are using, I can tell you how to set the threshold in order to render caustics.
It does but you need to use the link to an image (
https://i.imgur.com/cK5GQWo.png and
https://i.imgur.com/Dzng4qT.png), not to a web page:
Re: Caustics on Car Paint doesn't work
Posted: Thu Dec 02, 2021 4:56 pm
by AcidNemesis
Dade wrote: ↑Thu Dec 02, 2021 3:32 pm
Car paint is a glossy material and glossy material caustics are rendered only if you set the light tracing/cache glossiness threshold over the one used by the material (otherwise the material is excluded). If you post a scene of a cube over a plain with the carpaint material you are using, I can tell you how to set the threshold in order to render caustics.
https://drive.google.com/file/d/1SkV9da ... sp=sharing
Doing it the good old way with Google Drive ! I added a simple plane with some noise to get the caustics. Other than that I changed nothing in terms of settings.
Oh thanks for that !
Re: Caustics on Car Paint doesn't work
Posted: Fri Dec 03, 2021 9:44 am
by Dade
I'm not sure if you are really aware of what you are trying to render: your scene is illuminated only by caustic so it includes only SDS paths. And the light path of including carpaint is a (nearly) all specular path: all specular paths from not intersectable light sources, can not be rendered ... at all. However thanks to the "(nearly)", it can be done.
This is the original test scene:
You have to:
1) disable light tracing (because it is not particular useful here and we need to use caustic cache anyway);
2) the caustic PhotonGI cache glossiness threshold to 0.0 (so car paint is not considered a specular material).
and you get:
As you see, caustic on car paint start to be visible. In order to reduce the "blurriness", you may want also to:
1) set caustic cache photon count from 100000 to 500000
2) set caustic cache lookup radius from 0.075 to 0.05
3) set caustic cache min. radius from 0.075 to 0.02
4) set caustic cache radius reduction from 96% to 99%
and you get:
P.S. I disabled sky2 light source in the test scene so the result is more clear.
Re: Caustics on Car Paint doesn't work
Posted: Fri Dec 03, 2021 11:30 am
by AcidNemesis
Thank you so much ! I'll try that as soon as I come back home ! I'll post a render of the final look !
Re: Caustics on Car Paint doesn't work
Posted: Fri Dec 03, 2021 8:55 pm
by AcidNemesis
Okay so after tampering a bit with the values, I got something "satisfying", I can definitely do better but it's a great start, thanks again !