Chaos Corona Forum

Chaos Corona for Cinema 4D => [C4D] General Discussion => Topic started by: ASIMO on 2022-05-23, 17:55:00

Title: AO DIRT PROBLEM / SURFACES + EDGES
Post by: ASIMO on 2022-05-23, 17:55:00

Dear Community

I have a question regarding the AO shader, mostly used for dirty edges. I use it for concrete objects in architecture.

From time to time a face a problem I can not solve as the Max. Distance also includes the objects surfaces, not only the edges.

See screenshot with the object gets colored red in thin parts or where surfaces get close.

For me it seems impossible to make a thin object (concrete plate) without getting dark or colored on the surface when Max. Distance is bigger.

Is there a work-around or a different function ?

Thank you so much for your help.

Asimo

Title: Re: AO DIRT PROBLEM / SURFACES + EDGES
Post by: TomG on 2022-05-23, 17:58:27

Have you tried the new Corona Curvature instead, which is closer in functionality to the V-Ray dirt map?

Title: Re: AO DIRT PROBLEM / SURFACES + EDGES
Post by: ASIMO on 2022-05-23, 17:59:31

Hello

Thank you for your reply. No not yet. I will have a look :)

Title: Re: AO DIRT PROBLEM / SURFACES + EDGES
Post by: ASIMO on 2022-05-25, 14:25:24

Hello

So I tried the Corona Curvature. Basically this is a nice feature, but still have similar problems, since the red colored edges shins through the outer geometry. See attachment with settings.

Also I do not understand the logic of the AO. Why is there an effect visible although two elements are not intersecting at all ? See the two cubes.

This seems to me the main problem as it should only influence surfaces when they are really touching, no ?

Best – Asimo

Title: Re: AO DIRT PROBLEM / SURFACES + EDGES
Post by: TomG on 2022-05-25, 14:27:16

AO is simply "is the surface occluded?" in other words, is something casting a shadow onto it (this is the main original use of AO after all, to fake contact shadows). PS - by casting a shadow, this is not related to shadows from actual light sources in the scene of course, just "close enough it would be casting a shadow from rays from all directions from say an env. light or from light bouncing evenly around the scene"

Title: Re: AO DIRT PROBLEM / SURFACES + EDGES
Post by: ASIMO on 2022-05-25, 14:33:49

Thank you for your reply. This means the to use it for dirty corners and so on is not really the correct way then ?

Or to put it in other words :

To make a concrete with worn edges it would be correct to go with the curvature tool ? Or what would you recommend to have best control on this ?

How would you control the direction offset ? It seems this is only possible with AO ?

Thanks again :)

Title: Re: AO DIRT PROBLEM / SURFACES + EDGES
Post by: TomG on 2022-05-25, 14:43:58

Yes curvature is the preferred solution for this (as you won't get that "object nearby seems to be casting a shadow" effect - it will only depend on how the geometry is changing at that point, not on other objects or other parts of the same object "casting shadows").

I think combinations of Color Spread, Ray Directionality, and Max Distance should let you achieve similar results to the direction offset (been a while since I used AO as dirt though I confess, so I may be wrong in what that let you do.....)

Title: Re: AO DIRT PROBLEM / SURFACES + EDGES
Post by: ASIMO on 2022-05-25, 14:45:11

Thank you so much for your support.

I will give it a try to figure it out :)

Title: Re: AO DIRT PROBLEM / SURFACES + EDGES
Post by: Beanzvision on 2022-05-25, 14:57:10

If you're up for some light reading, we also have this: https://support.chaos.com/hc/en-us/articles/4528463913105-Corona-AO-Shader-C4D :)

Title: Re: AO DIRT PROBLEM / SURFACES + EDGES
Post by: ASIMO on 2022-05-25, 14:58:28

Very nice ! Thank you :)

Title: Re: AO DIRT PROBLEM / SURFACES + EDGES
Post by: Beanzvision on 2022-05-25, 15:00:26

Actually, I meant to share this one instead ;)
https://support.chaos.com/hc/en-us/articles/4954258906385-Corona-Curvature-Shader-C4D

Title: Re: AO DIRT PROBLEM / SURFACES + EDGES
Post by: ASIMO on 2022-05-25, 15:02:59

Even better ! Nice feature with that Outward / Inward option !