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one side of mesh inverted (mirrored normal map)

ZBrush Usage Questions
#1

Hey all, I am pretty new to ZBrush, and I’m having an issue where one side of my mesh seems to be inverted when I apply my normal maps. I created my low poly mesh in 3D Max, and I used both ZMapper and XNormal to export my normal map, and both apps had the same result.

I am using a mesh with mirrored UV’s. I’ve heard this can be problematic if it’s not set up right, but I’m not really sure the right way to set it up.

When I discovered the problem, I tried deleting the bad half of my mesh and adding a symmetry modifier, and also just mirroring and reattaching the other side. Those didn’t work. I also tried importing the remade mesh back into ZBrush as my low poly, but the mesh exploded when I tried going back up the subdivision levels.

I’ve heard that ZBrush uses vertex numbers for the low poly, so I guess that’s probably why the mesh exploded when I brought in a rebuilt low poly mesh.

I’ve found snippets of information in forums about this problem, but not enough info to be useful.

Have any of you out there dealt with this issue?

Thanks!!

#2

Could you post up some images of the problem, the UV layout, and anything else that you think might be helpful?

I am pretty sure I know what you did wrong, but that is a very long write up, and if I’m wrong, I really don’t want to go through all that :smiley:

#3

Well, apparently I’m an idiot. I set up my mirrored UV’s on top of each other, before I knew I wasn’t supposed to do that. I didn’t realize that I never offset them. As a test I exported the low poly back out of ZBrush and offset the UV’s in Max, then I imported them back into ZBrush as my low poly and now the normals are fine. So goast666, sorry for wasting your time.

I really still wouldn’t mine hearing what you though my problem was though, if you can write the shortened version. I’ve seen a lot of posts talking about half the mesh normals being flipped and nobody seems to know what to do about it.

I know it worked for me this time, but is just making sure the UV’s are offset the answer?

#4

either it’s an offset, or I grab the mirrored version and shrink it and make it very small and throw it in some empty space…the only reason I do that is so I don’t have to break my mesh everytime I want to do a normal check in Zmapper.

And the long version was going to be explaining what UV space is, and how to offset it, etc. So you saved me the headache of writing it again.