Corona Renderer Forum

Corona Renderer for 3ds Max => [Max] I need help! => Topic started by: inatosema on 2014-12-28, 05:37:29

Title: Corona Displacement
Post by: inatosema on 2014-12-28, 05:37:29
Has anyone used corona displacement over corners?

Vray has an option to "maintain continuity" around edges preventing the mapping to "tear" around corners... I dont see an option for Corona... as a result the map "tears" around the edge... is there a way to fix this?
Title: Re: Corona Displacement
Post by: maru on 2014-12-28, 13:41:19
Add "smooth" modifier (not meshsmooth or turbosmooth - just "smooth") and maximally smooth the mesh, then render. Or you can manually tweak smoothing groups.

This will probably need some fixing in the future. It sometimes looks bad, for example on boxes with hard edges.
Title: Re: Corona Displacement
Post by: inatosema on 2014-12-28, 16:44:44
Pardon my ignorance.  What do you mean "maximally" smooth the mesh?
Title: Re: Corona Displacement
Post by: romullus on 2014-12-28, 18:56:48
Here's a little example:

Title: Re: Corona Displacement
Post by: Alexp on 2015-03-25, 16:01:39
for boxes are ok, but for complex models?
Title: Re: Corona Displacement
Post by: romullus on 2015-03-25, 16:16:42
For complex models it's the same principle. You can add support edges by hand or automatically subdivide surface by adding modifiers like tesselate, subdivide, meshsmooth. Although complex models usually has more dense geometry from the start.
Title: Re: Corona Displacement
Post by: Alexp on 2015-03-25, 16:48:07
For complex models it's the same principle. You can add support edges by hand or automatically subdivide surface by adding modifiers like tesselate, subdivide, meshsmooth. Although complex models usually has more dense geometry from the start.

I can not understand how it works, at all ...
Title: Re: Corona Displacement
Post by: maru on 2015-03-25, 17:08:39
What strength of displacement did you set?
Are all the vertices of this model welded? Did you try with smoothing the model?
Title: Re: Corona Displacement
Post by: Alexp on 2015-03-25, 17:15:49
Its welded and smoothed, and here you can see the disp_map I use
Title: Re: Corona Displacement
Post by: romullus on 2015-03-25, 17:31:55
You're touching wrong buttons. Set displacement to screen size mode (value 2), max subdiv per poly set to 100. Now go to material and look for displacement group in basic options. Set max level to desired value and you're ready to go.
Title: Re: Corona Displacement
Post by: Alexp on 2015-03-26, 02:09:05
You're touching wrong buttons. Set displacement to screen size mode (value 2), max subdiv per poly set to 100. Now go to material and look for displacement group in basic options. Set max level to desired value and you're ready to go.

My results. I dont know.
Title: Re: Corona Displacement
Post by: romullus on 2015-03-26, 09:28:28
You have to assign one smoothing group for all polygons.
Title: Re: Corona Displacement
Post by: maru on 2015-03-26, 10:22:43
Easiest way would be to add "smooth" modifier like in first image here:
https://coronarenderer.freshdesk.com/support/solutions/articles/5000529362

You can also check the links at the bottom of the page for other displacement problems.
Title: Re: Corona Displacement
Post by: Fritzlachatte on 2015-03-27, 10:41:12
I was wondering why nobody already considered the alternative use of the standard (non vray-) displacement modifier.
While playing around, I found a lot of benefits. While using it, there is a proper preview of mesh-deformation.
I tessellated / smoothed both meshes, but when I use the corona displ.shader option, I donĀ“t like how it handles the details
and transitions between e.g. grout > bricks.
Another point is the fact, that I can collapse the object with the former displacement to a new "bricky" mesh, which might safe render time.


I hope nobody will abuse me for this proposal, just an idea.
Title: Re: Corona Displacement
Post by: maru on 2015-03-27, 10:46:27
I was wondering why nobody already considered the alternative use of the standard (non vray-) displacement modifier.
Sure, whatever works for you is fine! But this workflow is not always usable. And no one said Corona's displacement doesn't need improvements.
Title: Re: Corona Displacement
Post by: Fritzlachatte on 2015-03-27, 11:34:15
Quote
But this workflow is not always usable

And I thought I found something similar to the holy grail :-) But because of my attending interest do you know examples of operations the modifier will fail.

Because of the variegated adjustments of fine-tuning like blurring, decay and the option of extra noise/ 2nd displ. texture etc. it makes a good job. 
Title: Re: Corona Displacement
Post by: maru on 2015-03-27, 11:40:28
But because of my attending interest do you know examples of operations the modifier will fail.
First thing is that displacement modifier needs an uniformly tesselated mesh. Corona's displacement is "adaptive" - it can produce ultra-small details if they are needed and no subdivisions in other parts of the mesh if they are not needed. To re-create what Corona is doing when you are dealing with a detailed displacement, you would have to subdivide the whole mesh untill you run out of ram and your max crashes or manually make the mesh more dense where it is required (which is insane).
At least that's how I see it. Hope I didn't write anything ultra stupid. :)
Title: Re: Corona Displacement
Post by: romullus on 2015-03-27, 11:52:04
While displace modifier can be very usefull in certain situations, it has significant drawbacks over micro polygonal displacement. First of all, your files will be much heavier, mesh becomes much harder to modify and displace isn't view dependant, which is very resource wasteful.

Of course it has its own benefits. Mainly it can be treated as modeling helper.
Title: Re: Corona Displacement
Post by: Fritzlachatte on 2015-03-27, 12:09:11
that is a really interesting aspect, for the bricks rocks etc. it felt quite fast, but the fact of view independents might become a problem.
I had the misgiving hunch by a lack of "ultra" fine details like wooden planks in closeups and whatever needed ultra high details.
Quite often I had the feeling corona displ. "kills" fine details or blurs to much at corners but as usual (sadly) everything has pros & cons.
But I thank you for these informations, sounds logical and far away from "ultra stupid";-)