Seams in mirrored geo

JoshWilkinson

I have a mesh that is mirrored but has an obvious seam. After playing around, I have isolated the problem to an issue with the normal map.



If I understand correctly, normals default to tangent space and when UVs overlap the normals face opposing directions. Rumor has it the issue is resolved if the normals are changed to world space? Is that true, and if so how do I do so?

kodde

I think this has to do with not only the vertex normals but also how the tangent and binormals are aligned. I think you can handle this either by code or by shaders. A general good rule when it comes to working with normal maps is to bake your normals with the same tangent basis and your engine will be using.

I'm not familiar with UDK so someone else will probably have a better answer for you.

cptSwing

provided you're exporting to UDK, maybe http://www.3dmotive.com/exportingqualifiednormals/ will help..?

mdeforge

Are your UV shells stacked by chance? If so, the normals won't be correct.

Adam L. Gray

This is an age-old problem, and has been brought up over and over again. And as far as I know, there's simply no way to fix this completely.

This is about as close as you get: http://udn.epicgames.com/Three/LightMapUnwrapping.html (bottom of page)

but it'll still cause problems with the specular I believe, unless you use dynamic lighting.. more info about that on the very bottom of the page.