Displacement Map Seams (zbrush, scan)

Jonathan85

Hello im having problems with displacement maps generated in zbrush and rendered in 3ds max 2012 vray 2 using the vray displacement modifier. The displacement map has seams :-(, i tried what i could but they still persist.

- Using just the displacement map (not normal or diffuse), and in vray displ. modifier
- 8192*8192 px, exr 32 bit
- Zbrush 4R6, see pic for gen. specs
-The map opened in photoshop and flipped vertically (since it did not matc hthe orientation), and again resaved as exr 32 bit, could this cause the seams?
-I also tried the UV map border with smaller value like 4 or 6, the same result (or even worse i dont remember).
- I have correct gamma setting while importing the map, that issue is not the problem

What am i doing wrong? I was doing the uvw map layout in 3ds max and imported it back to zbrush. If i use the default uvws which are generated in zbrush the seams are almost not visible (still there but it look good enough), but i would like my own uwv map...



http://postimg.org/image/516ebuhqb/

Norstu

Photoshop does something to EXRs. I don't think that it fully supports 32bit floating point EXRs. Just flip them during Bake or in Max set Bitmap U or V value to -1.0.

Akin Bilgic created an awesome tutorial on Accurate Displacement map workflow = http://www.cggallery.com/tutorials/displacement/

However i've gotten near perfect results with little effort using 3D Coat for displacement map baking.

Here are my steps:
3D Coat
1.Go to Retopo Room
2.Load Reference Mesh (high poly)
3.Import Low Poly via Retopo Menu (do not snap to high poly)
4.Bake Window Settings:
-Use Retopo Mesh to Bake
-Smooth Mesh
-UVs = Smooth but keep edges
-Enter values for In Scan & Out Scan Depth (Use Bake Scan Settings to work this out before)
-Create Padding
-Displacement Type = Grey Based, Not Normalized

3ds Max
Apply VrayDisplacement Modifier, set Amount to 1 & Shift to -0.5
Thats it!! .
**You can try applying a Turbosmooth modifier below Vray Displacement for better results.
**Displacement Maps are very sensitive to scale. So make sure that you don't change scale of model.

Jonathan85

Hmm i dont use topogun, does anybody else have some tip? None of what you wrote helped me... :-(

currently i have "solved" the issue with different uvw layout (automatically created) in max, which doesnt seem to have the problems with seams, altough i would like to now why the previous had problems... any tips anybody?

Norstu

If you turn off the Turbosmooth modifier, does the problem still occur?

Jonathan85

Yes Norstu, i tried of course even that, the problem still occurs.
I have tried even edge padding (or how is it called in Zbrush) at maximum (i believe its 16) and then something like 4, the problem still occurs.
It is not that usual problem, am i right?

I will try to retopo the hipoly mesh again with different topology so far i have been trying the test with the original retoped topology and "just" changing the uvw layout.

does anybody else have some other tip?

I also tried using just 16 bit displacement maps (tiffs instead of 32 bit exr), the problem is the same. :-(....

Norstu

Upload ZBrush file somewhere (dropbox, google drive) so that we can take a look at it.

Jonathan85

Zbrush file with the original hi poly mesh and low poly mesh?

or will be just the obj low poly mesh by sufficient? (im not sure im allowed to upload the hipoly model, that why im asking)

Jonathan85

Ok so i have tried even this workflow, but it didnt help:

http://polygonspixelsandpaint.tumblr.com/post/19733351349

What choices remain for me :-(?

Jonathan85

Hm... ok i tried a smaller texture to generate from zbrush (4096*4096px instead of the 8192*8192px) and the seams are still there but are a lot less visible now, somewhere they vanish overall, so nice, that will probably do it.

Other than that, is there any way how to use even the 8192px maps? Altough i dont think a lot of people for which i will be making this will need such a high resolution its always nice to be able to use the high resolution.

So it seems its ok, but still does anyone have some other tip?

Jonathan85

Ok so the only way i have found out and works at least a little bit is this:

1) follow this tutorial (make all uvw island rectangular like): http://polygonspixelsandpaint.tumblr.com/post/19733351349
2) and use smaller (4096px displk. map).

but im not sure how other maps (like difuse or normal) will look like with this stretching of textures, i will have to have a look

User2015

This may help:

You can get rid of displacement map seams by this way:

• Import your mesh with displacement texture to Mudbox.
• In Mudbox convert your mesh to PTex (be sure PTex have a little bit lower resolution than your texture).
• Import another copy of your mesh.
• Then do "Transfer Paint Layers" from PTex mesh to UV mesh (be sure "Smooth Target Models" - off).
• Export texture from UV mesh into a file.
• That's all, now displacement seams almost disappear.

You can use this lesson: http://area.autodesk.com/blogs/rodrigo/ptex-to-uv

Beavertron

Basically stay the hell away from zbrush displacement maps and even normal maps. everything is back to front, upside down, have to flip G for max, something else for maya. It's a pixologic mess, and no excuse for it. Displacement map seams are a game breaker. Absolute cr*p and don't waste your time trying to debug displacement map seams. Create your maps in something like mud box. quality perfect maps no stupid white seams or flipped channels. Pathetic waste of time. Been there and switched software because of it. This is a lazy bug that hasn't been fixed or addressed with imported models with UV layouts created in another app for a base mesh. If I could I would probably strangle one of the developers for the amount of time waste and frustration with this poor section of the software. To me, what's the point of all those wonderful brushes and effects, if I can't get the dam object out into another software scene to render. I'm not a simply trying to use keyshot here. mud box is beautiful when it comes to displacement and normal map creation. shame it doesn't match the brush and base mesh creation aspect of zbrush. 

Try this, create what you need in zbrush via, zap here's, dynamesh etc, clay build ups. Leave off the finer details, Retolpologise or zremesher, export out to mud box or another to create your finer high end details, then create your maps from there.