Displacement broken edges

[LudvikKoutny]

Hi,

this has been probably asked at least dozen times before, yet I could not find some reasonable answer anywhere. I have a simple mesh and I am trying to displace it, and whatever I do, I just can not get rid of holes in my displacement. I tried smoothing my entire mesh into one smoothing group, tried edge continuity, tried different displacement modes, but nothing simply works. The edges of UV isles are not aligned, but it's physically impossible to unwrap something like tree mesh without seams, there will always be some.



Does that mean V-Ray simply can not handle displacement on meshes with UV seams?

I am a bit desperate here, because this job needs to be done asap and I went into it expecting that I can count on V-Rays production proven displacement. Definitely did not expect to struggle with something so simple, so any help is much appreciated.

Thanks in advance.

[Companioncube]

people are doing this all the time so it's not vray. maybe you could give more information about the displacement map and what program it was created in. maybe upload the file, screenshot your displacement settings. are you using a vrayHDRI map to load the texture? does the texture have edge bleeding on the seems. a screenshot of your UVs.

more info

[Pixelab]

I've found this article by Akin Bilgic really useful, but it's for displacement generated from zbrush. It contains a lot of useful information, maybe you'll find something to help you

http://www.cggallery.com/tutorials/displacement/

[Deflaminis]

Try "Keep Continuity" and if you are using 32bit displacement, make sure your offset is -1/2 of your displace amount.

[Morbid Angel]

this is not vray's doing. If there are seams on your displacement map, then there are going to be edges. If you simply plug displacement map into light material and render that without displacement, you will see edges there. Those edges are difference in height.

There is no real solution to this except painting the displacement map seams in 3d paint software like mari or mudbox.

[Deflaminis]

Oh, I thought it was a zbrushed model.

[Morbid Angel]

he didn't mention weather it was. I deal with similar sculpts on multi tiled characters every day, and we get the edges lining up no problem.

[LudvikKoutny]

Alright, here are some answers:

It's 16bit tif displacement.

It's not Zbrush model.

There are UV seams exactly on the places model falls apart, and UVs do not line up on those seams, but that's the entire point. UV borders not lining up is no reason for displacement to break apart. Both 3ds Max's native displacement and Corona displacement can handle this model with no holes whatsoever.

I am not using VrayHDRI because it would make no sense if using VrayHDRI vs using Bitmap had any effect on this. But just to make sure, I did try VrayHDRI and indeed, it has no effect on it.

[LudvikKoutny]

There is no real solution to this except painting the displacement map seams in 3d paint software like mari or mudbox.

There is a real solution to this, and both 3ds Max's native displacement and Corona displacement do that. They simply keep the edges together. Every production-ready displacement solution should.

This is Max's displace, no problem:


This is Corona's rendertime displacement, no problem:


This is V-Ray, with edge continuity enabled (I tried almost any threshold value imaginable):


I still believe I am missing something. I doubt people would praise V-Ray's displacement if it could not fulfill basic requirement of not breaking geometry apart. This was an issue with very early Mental Ray versions, but even they fixed it promptly.

[Macker]

What are your displacement settings?

Are you using displacement in the material, or via the displacement modifier? We're shooting in the dark a little here.

[LudvikKoutny]

What are your displacement settings?

Are you using displacement in the material, or via the displacement modifier? We're shooting in the dark a little here.

Right, forgot those. Here you go. But I doubt you will have any luck, as I tried fiddling with all of them already.


In fact, here is a simple repro scene, if you feel like pulling your hair out today
DisplBreak.zip

[Pixelab]

Did you load your displacement map in gamma 1.0 ? It should be loaded in linear (assuming you work in LWF)

Loading displace and/ or normal maps in 2.2 (or default in max) will give wrong results. Corona gives a warning about that but not VRay.

[LudvikKoutny]

Did you load your displacement map in gamma 1.0 ? It should be loaded in linear (assuming you work in LWF)

Loading displace and/ or normal maps in 2.2 (or default in max) will give wrong results. Corona gives a warning about that but not VRay.

1, Yes, I did.

2, It would have absolutely no effect on if edges are broken or not. It would only affect what distances different tones of grey represent.

3, Corona prints a warning about wrong normal map gamma, not wrong displacement map gamma.

[Companioncube]

in this particular case the only thing you can do is bake the texture then fix the seams in your program of choice.
It looks like corona does some kind of blend on the seams, no idea but something like that.
In your sphere example file, which is a different case from your tree model, you could just use a triplanner which would blend the seams.

It would be nice if for examples like your tree it would not break. Best just to email vlado your tree file and ask what he can so in the future.

[Morbid Angel]

I mean if there is a working solution even in 3ds max native displacement, then there should be no reason why vray can't handle this situation either...