ZBrushCentral

How to fix Normal Map artifacts?

ZBrush Usage Questions
#1

I get annoying artifacts displaying with my normal maps. Just wondering what the most effective way to fix them is?

You’ll notice them around the adam’s apple and under the ears on the back of the head. There is also a slight bit of distortion around the lips/nose of the model.

I used XSI to lay out the UV Map and Zmapper to generate the Normal. I’m guessing my UV layout is potentially part of the problem but I can’t seem to work it out on my own no matter how I tweak it.

Any help is greatly appreciated -Derek

Attachments

artifacts.jpg

#2

Well I seem to be having some luck using the “render Region” option of zmapper and tweaking the settings on various regions of the generated map individually. If that is all there is to it, no responce needed, any other tips and tricks still much appreciated -Derek

#3

Even better I’ve found using the smudge tool in Gimp/Photoshop to clean up any hard edges does the trick effectively. I know I’m answering my own question here but sometimes thats the only way, I’ll update again if I find any more tricks in case someone in the future does a search and finds this…

#4

I had this problem at one time. My problem was that the scale of the mesh inside ZBrush was all screwed up. It was too small, so I scaled it up so it looked correct, but when I did this my normal maps got artifacting just like that. So I just scaled it down a little bit and they went away.

So maybe your problem is based around the scale of your mesh?

#5

Derek,

Youve got two things going on here. First, your models left and right half UVs are overlaid, so ZMapper is generating the normal map twice. At the central seam this causes confusion and a sort of inside-out negative effect, noticeable on the throat.

The other point is that your base mesh and hi-poly mesh are too far from each other in some places for ZMapper to reach. The flat, round marks on the back of the head are probably caused by this. You need to increase the raycasting Max Scan Distance in ZMapper`s Misc. tab.

On another note, Photoshops Liquify plugin is handy for straightening up edges that ZMapper bent out of true. Unlike the Smudge tool it doesnt blur the image.

Cheers,

R

#6

“First, your model`s left and right half UVs are overlaid,”

Is there a better way to do this, the character is supposed to be optomized for realime, I figured overlapping UV’s would do the trick but yes, it does become a pain…

#7

Overlapping is standard procedure for games. Grin and bear it!

However, if your character is going to display damage marks, you`ll want to give all polys unique UV spaces. Talk to your programmers about it.

Cheers,

R