ZBrushCentral

Displacement Baking Inaccuracy/Error

ZBrush Artworks
#1

I’m currently trying to displace a base face mesh in Maya 2017 and render it in Arnold. I have a friend who has been using zbrush for years and, while he can’t remember how to solve the problem I’m having, he’s 99% sure that it’s a baking problem from zbrush, and not a rendering issue.

While the issue is illustrated in the image, I’ll summarize it here as well:
Basically, when baking out 32 bit exr displacement maps, it appears that zbrush runs into problems baking smooth transitions in certain areas that push in. Take, for example, the inner-top portion of the ear in the images (the top red arrow). In the zbrush sculpt, that area is a nice, concave shape with no harsh flats: a smooth transition. In the baked map, however, it starts off transitioning well, but then it seems to hit a value of 0.0, can’t push in anymore, and creates this sharp edge and flat plane where it should be concave. My image shows the problem happening in the ear, but I also have this issue around the corners of character’s eyes and around nostrils.

I have tried MANY things to fix this so far, and all have failed. I’ve tried:
Using/not using adaptive
Lowering/increasing map borders
Using/not using dsubpix values
Deleting lower subdivs so that the new lowest subdiv more closely matches the highest subdiv (obviously this helps a little bit, but the problem is still there)

So far, the only thing I’ve found that has helped at all is turning off autobump in the displacement node in Maya, which softens the hard edge slightly.

problem.jpg

Attachments

problem.jpg

#2

See if the following link helps. Settings at bottom of the article. Sorry, I don’t use Maya and Arnold, so I can’t help you directly.

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

#3

Thank you so much zber, I have actually seen that page before, but since you posted it I went through the whole thing again and found the cause of the problem.

The issue was NOT due to baking inaccuracy; it was due to some … misinformation/lack of information I learned from one of my courses in school (I’m still a student). Basically, I was taught that displacement and other single channel maps could only have values between 0.0 and 1.0. I didn’t know until I read all the way through the link you gave that 32 bit exrs could hold values well above and below that.
Because I thought they could only hold values between 0.0 and 1.0, I assumed that a “remapFloat” node that had an output min of 0.0 and 1.0 that I had between my displacement map and my displacement node was technically doing nothing, when it was actually taking any negative values zbrush had written to the exr and bumping them up to 0.0, resulting in the flat areas where it should be pushing in.

Thanks again zber

#4

I’m glad you found a solution! :+1: