Mirrored normalmap seams cant get rid of

Excelerator · January 19, 2017, 7:04pm

I’ve done this before successfully but had used an older version of Blender.

I am exporting to FBX for the Unity game engine, but I’m always getting these seams between my halves. I did bake the entire model while it was still connected to it’s other half, so that shouldn’t be the cause.

It seems that the problem lies within how the tangents are aligned, but I don’t see any way to visualize these tangents in blender. The reason I know this is that I am getting different results in Unity when I change the tangents.

If they are imported from the model, the seams appear, but the model’s sides appear correct when rotated 180 degrees.

If they are set to not import, the seams go away, but the model’s sides appear different when rotated 180 degrees.

It seems like something got flipped in the tangents, but I have no way to tell.

This is an extremely common technique for normal mapping and it shouldn’t be this hard. But it seemed like this used to work back in the old version of blender when using a blender render. You can see that red car in the picture has it done right. The bullet train is what I’m working on now. I would appreciate any help on what to do. Thanks.

Screenshots are from Unity game engine:

Secrop · January 20, 2017, 3:21am

Can you post the model with the normal texture?

Excelerator · January 20, 2017, 10:12am

bulletTrain6.blend (5.33 MB)

Excelerator · January 20, 2017, 1:00pm

See? Look at this. This is supposed to be possible. I Exported this fbx model the same way, but from an older Blender. I cant think of anything else other than this is a bug in the new Blender.

I asked my friend about it… we tried lots of things with checkboxing U and V in the mirror modifier. Nothing works. It would be something else if there was truly a way to visualize tangents and bitangents, but this is crazy to expect someone would be able to make efficient models for videogames if there’s nothing I can do about it.

Excelerator · January 21, 2017, 2:32pm

Hey. I figured it out. If you look at that normalmap I posted, you might notice it is suspiciously bright. That’s because it is. When it doesn’t hit it’s neutral color on flatter areas, that’s when you get the problem. So, I tried another bake, only with the halves separated, and it baked it back to it’s regular look. So, after all the designing is done I’m going to try splitting the texture in half and re-map both halves. I think this is ultimately a problem when overlapping with cycles bakes. They just can’t overlap or it becomes too bright and wrecks your shading.