Inverted normal map on parts of the model

Cthogua

When I bring my low poly model into Substance Designer and apply the normal map I baked out of Max the portions of the model that were created using symmetry are displaying "inverted." I know that with some renderers it doesn't like it when there's flipped UVs and it usually displays the flipped parts as if the nm were "inverted." Is this a problem in SD as well? It seems like the first model I used SD for had stacked UVs and I didn't see this issue. I also recently learned that Max doesn't display normal maps the way it's baker renders them so you can't really trust the Max viewport display when it comes to fixing seams and other issues. I checked the normals on the actual mesh in Max too and they all looked fine, no inversions there.

Thoughts? Ideas? Acrimonious accusations?

Here's two screens from Substance where you can see the inverted normal map sections and a screen from Max where you can see it displaying mostly correctly aside from the seam on the corner which doesn't show up in Substance.

Jerc

What version of 3dsMax are you using and what format did you export to?

Cthogua

It's Max 2012, and I exported the mesh as a .FBX.

Cthogua

I just tried it as an OBJ and there were no flipped normal issues. I guess that means it's probably 2012's FBX exporter then?

Jerc

FBX stores mirrored tangents badly with older versions of 3dsMax. OBJ doesn't store tangents, so SD rebuilds them correctly

Cthogua

Ah, ok. I was wondering about the tangents/binormals since OBJ doesn't store them. Good to know SD rebuilds them. Thanks again!

Ieva

@Jerc thanks a lot. I had similar problem. Didn't occur to me to try export .obj instead of .fbx