Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] I need help! => Topic started by: romullus on 2017-10-26, 12:00:34

Title: Discrepancy betwen Corona and native displacement
Post by: romullus on 2017-10-26, 12:00:34
I noticed that there is quite big discrepancy between Corona displacement and native displace modifier. If i take two identical flat planes, assign Corona material with displacement to one of them, and subdivide and add displace modifier to another, then on render they both gives almost identical result. But now, if i add noise modifier to both planes or do arbitrary geometry changes, so the planes won't be flat anymore, then on render they both gives significantly different results. Am i right, that Corona calculates displacement from mesh normals differently than native displacement does? And more importantly, is there a way to make those results to match?

In attached renders, green plane is with Corona displacement and red one is with native displacement.
Title: Re: Discrepancy betwen Corona and native displacement
Post by: romullus on 2017-10-31, 22:42:35
BUMP! I think this is pretty serious issue, unless there's other simple way to scatter objects over displaced surface, than to make a copy of that surface with native displace modifier on top. For now, i'm baking Corona displacement in to mesh and use it as scatter surface, but that is a big pain in da ass.
Title: Re: Discrepancy betwen Corona and native displacement
Post by: maru on 2017-11-01, 11:06:54
Can you explain your setup? The noise modifier (or other deformation) is below the 3ds max displacement modifier? So the geometry is deformed first, and then 3ds max displacement is added?

Have you tried with the corona displacement modifier?

Also, are you using "use existing mapping" option in the 3ds max displacement modifier?
Title: Re: Discrepancy betwen Corona and native displacement
Post by: maru on 2017-11-01, 11:21:40
Here is what I am getting.
Title: Re: Discrepancy betwen Corona and native displacement
Post by: romullus on 2017-11-01, 14:30:30
Can you explain your setup? The noise modifier (or other deformation) is below the 3ds max displacement modifier? So the geometry is deformed first, and then 3ds max displacement is added?

Have you tried with the corona displacement modifier?

Also, are you using "use existing mapping" option in the 3ds max displacement modifier?

Yes to all of that. I'm attaching scene, so you could test it for yourself.
Title: Re: Discrepancy betwen Corona and native displacement
Post by: romullus on 2017-11-01, 14:49:29
Ups, i found where problem is. It's my mistake in scene setup. Thanks for test scene maru, by analyzing it, i was able to understand where my mistake was! :]
Title: Re: Discrepancy betwen Corona and native displacement
Post by: PROH on 2017-11-01, 14:58:40
Glad you got it solved, but you did mention two other things t hat definitely could use some attention:

- Baking Corona displacement to mesh. This should be an easy 1 click operation, instead of the present PITA

- C-Scatter following displacement. This would be great to have :)

Regards
Title: Re: Discrepancy betwen Corona and native displacement
Post by: romullus on 2017-11-01, 15:07:14
First one is not interesting for me, but i would definitely vote for the second one :]
Title: Re: Discrepancy betwen Corona and native displacement
Post by: maru on 2017-11-01, 16:58:46
- Baking Corona displacement to mesh. This should be an easy 1 click operation, instead of the present PITA
This means that you are aware of the current solution with exporting scene?
Title: Re: Discrepancy betwen Corona and native displacement
Post by: PROH on 2017-11-01, 18:36:04
Yes. And I think this could all easily be done under the hood with just one click. So why not?
Title: Re: Discrepancy betwen Corona and native displacement
Post by: Juraj on 2017-11-01, 19:13:41
First one is not interesting for me, but i would definitely vote for the second one :]

Interestingly the only scatter that does this (ForestPack) can't do it directly either (render-time), but it has sort of 'precompute' button that will simulate the disp.
Title: Re: Discrepancy betwen Corona and native displacement
Post by: romullus on 2017-11-01, 20:22:53
Ah, that would be acceptable solution. Someone should register that as feature request :]