Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] I need help! => Topic started by: DarcTheo on 2016-06-24, 10:01:05

Title: faceting in a sand material
Post by: DarcTheo on 2016-06-24, 10:01:05

Having trouble with a sandy object/material. It keeps rendering really faceted in raised areas. I've something similar on here before where if the object was a low poly you would get strange shading results so i tried smashing up a turbosmooth to 4 on the object but it didnt help. I also tried tesselating it and then turbo smoothing it and that also did not help.
I've attached some images of whats happening. If i turn the sun off its not as bad...but its visible on the shadow edges for sure. The sun is at intensity 1 and the size is 4, i thought size might help soften it.

any idea what i could do to fix this without drastically changing the lighting.

edit - ive also tried using the smoothing groups but the sun seems to just cause this faceting.

Title: Re: faceting in a sand material
Post by: PROH on 2016-06-24, 11:59:33

Hi. I'm pretty sure that this will change if you lower the bump value. I think it's an example of the terminator problem, that hopefully will be fixed in 1.5.

Untill then the only solution is to lower the bump value :(

Title: Re: faceting in a sand material
Post by: Juraj on 2016-06-24, 12:17:35

The issue is, if he lowers the bump, it will become literally unnoticeable.

Bump/normal mapping is not possible to currently use when any sort of more direct light is in scene. Even the weakest bump will cause terminator : /

In diffuse light, the Corona bump is fantastic, prominent, so bump mapping is great... as long as it works. With Sun, in organic shape, it does not.

You can do what I do, keep brutal turbo-smooth on (viewport-, rendertime 3+ ). Massive amount of polies, but does the job.... mostly. Sometimes it just creates smaller terminator.

Title: Re: faceting in a sand material
Post by: DarcTheo on 2016-06-24, 12:42:58

i pushed the polys a bit further, about 20 million on that plane instead of 4 million. (so many!) the artifacts are a lot smaller now but they are there. I couldnt reduce the bump without losing the grainy feel.

I definitely notice how bump doesnt work as well in stronger direct lights but diffused areas show it up much better.

Title: Re: faceting in a sand material
Post by: PROH on 2016-06-24, 12:50:44

Yes I know that lowering bump isn't great, but I also know that further tessellating isn't removing the problem, so it's really a pick of the lesser evil.

I deeply hope that this will get fixed soon :)

Title: Re: faceting in a sand material
Post by: maru on 2016-06-24, 14:50:07

Yes, it's definitely the terminator problem (https://coronarenderer.freshdesk.com/support/solutions/articles/5000516180-known-bugs-and-limitations).