Mudbox vector displacement in vrayDisplacementMod holes at UV seams

[jstrob]

Hi,

I really have to make this work. When I try to use vector displacement from mudbox in vray in 3dsmax I am getting holes in the mesh at UV seams. I just installed vray 2.20.01 to see if the new "smooth UVs" and "Smooth UVs at borders" options could get rid of this but it doesn't change anything.

You can see the problem in the following pictures:


If I zoom we can see the small hole almost everywhere on the UV seems...


I circled in blue the area of my map where the hole is happening.




In mudbox, I use smooth target models and creases & hard edges.

[Morbid Angel]

never worked with vector displacement maps and never had any success with them, but as a wild guess did you trying playing around with bitmap filtering, some times it filters too much along the uv seam. Just a guess though.

[vlado]

I'm afraid there will always be issues at the UV seams; the textures almost never match completely on both sides. That's one of the issues that PTex textures are supposed to solve. We don't support vector displacement for them just yet, but they should work better for regular displacement, especially if you set the filter width in VRayPTex to 0.0.

Best regards,
Vlado

[jstrob]

I will try with regular displacement and Ptex... or I will create geometry to patch the uv seams... Do you have any tutorial or tips for using ptex with regular displacement between mudbox and vray?

About vector displacement, there should be a way to add some kind of modifier above the displacement modifier that would allow us to smooth the uv seems by painting the region of the uv seems maybe.

[ndeboar]

Hey,

We are having the same issue here, getting great displacment results with vector displacment, but horrible uv seams. It would be great if someone could show how to export ptex displacments from mudbox to vray, havn't had any luck with my tests.

Nick

[vlado]

I wrote a short tutorial here: http://www.spot3d.com/vray/help/200R...udbox_ptex.htm

As you can see it's nothing complicated.

Best regards,
Vlado

[jstrob]

Thanks vlado for the tut.

But I just tried the mudbox/vray ptex workflow and I am getting a lot of artifacts.


Any idea?

[vlado]

Not sure about that one, can you get me your mudbox file to vlado@chaosgroup.com?

Best regards,
Vlado

[jstrob]

Hi, I think I just put a too large search distance in mudbox when extracting the displacement... I will have to test it later. I switch back to regular uv and regular displacement but I was getting the same problem and I corrected it by adjusting my search disctance. I will have to see if all goes well when I do this with ptex too, but my guess is yes.

[jstrob]

I finally did my test and I was right about the search distance being too high (it was around 100 and I lowered it to 15). But with the ray casting method you suggest to extract the map in mudbox, I was still getting a few bad artifacts in the most extreme displacement areas and in corners. But I tried with the subdivision method in mudbox and I got a very nice result!
original in mudbox:
3dsmax/vray:ray casting in mudbox:
3dsmax/vray:subdivision in mudbox:

[vlado]

Very good to know - thanks for the pointer!

Best regards,
Vlado

[wxyz]

Can you explain the subdivision nethod in Mudbox?

[jstrob]

You just choose the subdivision method when extracting the displacement that's all.