Chaos Corona Forum

Chaos Corona for Cinema 4D => [C4D] Bug Reporting => [C4D] Resolved Bugs => Topic started by: Silverwing on 2018-11-09, 14:12:17

Title: Bump is not taken into acount for reflective / refractive caustics
Post by: Silverwing on 2018-11-09, 14:12:17
I encountered a bug with caustic generation.
When you add detail to to a caustic generating surface (e.g. glass) like bump or normal maps, unfortunately the surface variations do not show up in the caustic pattern.

This this is in my opinion a severe limitation and could cause scenes to not look as realistic as they could. You can see this quite well with the unevenness of caustics refracting through a glass on a sunny day. Most glass like objekts in CG are rather perfect in their form. So adding little imperfections though bump or normals and getting those reflected in the caustics would bring a lot of realism to some scenes.

Attached are two renders. One with bump, where you would expect the uneven caustics to show up, but they do not.
Then another render using displacement to show how it should look.
Title: Re: Bump is not taken into acount for reflective / refractive caustics
Post by: mp5gosu on 2018-11-09, 14:17:25
This seems like a bug to me. The caustics rays should indeed use the shading normal, not the geometry normal.
Title: Re: Bump is not taken into acount for reflective / refractive caustics
Post by: Silverwing on 2018-11-09, 15:09:52
This seems like a bug to me. The caustics rays should indeed use the shading normal, not the geometry normal.

Thanks mp5gosu for backing me up on this. I was quite surprised to find out about that.
I also tried older versions of Corona and there seems to be the same problem. I also attached the scene. Although it should not be hard to reproduce!
Title: Re: Bump is not taken into acount for reflective / refractive caustics
Post by: Beanzvision on 2018-11-09, 15:44:06
Thanks for the report, It's definitely something we'll look into.