Normal maps issues

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  07 July 2013
Normal maps issues

I'm having two issues and I have no idea how to fix this and I've been trying to figure it out by myself for a long time now.

First problem is when baking normals with xNormal from a high poly mudbox sculpted model to low poly game model. Those inset lines are perfectly straight on high poly model, yet they bake with wierd irregular edges. I thought it was low poly model fault, but then I just baked it on a plane and the result is the same (screenshot). What could be causing this? I'm goin crazy, I really thought it was low poly fault but now I'm stuck forever...

Second problem I've been ignoring for some time, but I need to stop avoiding it. I keep getting wierd shading on low poly models I make in maya. Even though this is a perfectly flat object, there are triangles visible on it. Smoothing does nothing. Conforming, unlocking normals, turning to face and smoothing again, averaging, setting angle also does nothing. If it's for game it must be all triangles, so what is the problem? Everytime I do triangles that are uneven it breaks smoothing, is this normal behavior? Should I try to do even triangles? That would increase their number, I think I saw lots of irregular triangles on other people work and it was fine. It's insanely annoying.

Please help.
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  07 July 2013
First issue could be related to pixel in your texture area is too small to create nicely anti-aliased lines or your high poly detail is not chunky enough.

The 2nd problem could be related to your baking app not being synched to maya's normal map shader. It's a common problem between game engines and the software used to bake the maps.
  07 July 2013
You were correct with the first issue. Even though it looked sharp in mudbox preview window it wasn't sharp enough for xNormal to generate good map. I had to redo this part on higher subd. Thanks!

I don't know about the second problem. I make low poly model in maya, and the problem you can see on the screenshot appears right when I smooth normals in maya, before even going to other app for baking. It is the basic low poly mesh with no normal map job, only smooth generated by maya and it makes those artifacts. Then when I bake maps, it stays there only less visible, but still unnacceptable. Should baking fix those problems (it is not fixing them for me right now), or should I do something to make it work in maya before baking?

Thanks for help, I hope I'll soon be able to solve the second problem too.
  07 July 2013
Oh ok, i didn't read 2nd problem carefully, my bad. So you're having problems with geometry even before attempting to bake maps?

It looks to me like you could turn some edges and get rid of long thin triangles (by that i mean triangulate so that your edges travel the shortest distance possible). You should not have huge problems with that type of geometry tho, since the normal map is generated based on your model's normals. It could be a setting in xnormal, there's the option to bake exported, average and harden normals.

More things to try:
-Triangulate the whole model before baking, this will prevent the mesh exporter to randomly turn edges and become an altered version of your model in Maya which ends up with mismatched normals.

-Look for unwelded verts or open edges (you probably did but just throwing that in there)

-Never modify your low poly mesh after the normal map has been generated, if you do, you'll have to bake again.

Last edited by Psyk0 : 07 July 2013 at 11:27 PM.
  07 July 2013
I did triangulate before baking. I always clean up model before doing anything with it so I guess it should fix all the problems with unwelded verts etc.

The only setting in xNormal that gives me good result is to average normals (still with this second error)

Seems like this wierd shading is indeed caused by to long triangles. I have to increase tri count a lot to make it look good. Still not perfect. It's wierd, the surface is perfectly flat, yet it makes those errors... I thought people used long triangles all the time to reduce tri count, guess I was imagining things. If this is normal behavior I will naturally accept it. I plan to try modeling on something else like blender, maybe I have problems with my maya.

All the errors became invisible when I applied all the maps with textures and speculars together, but I know that they are there and it annoys me I could just ignore it since it is gone, but it was a training model, so I was suppose to do it as close to perfect as I can to learn some things. It is the only big issue left :/
  07 July 2013
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