Author Topic: Maya UVs not interpreted identically in SD?  (Read 1680 times)

(image attached)

Hello.

I have a normal map that looks fine in maya but does not display properly in Substance Designer. It appears to be a slightly different interpretation of the UV mapping.

Is there a UV smooth that is automatically applied inside of SD? Any insights into how I can get my SD preview to match my maya preview?

Thanks for your input!

(image attached)

Hello.

I have a normal map that looks fine in maya but does not display properly in Substance Designer. It appears to be a slightly different interpretation of the UV mapping.

Is there a UV smooth that is automatically applied inside of SD? Any insights into how I can get my SD preview to match my maya preview?

Thanks for your input!

That looks like an issue with the normal map interpretation. Each 3D program will use a different tangent basis to compute and view normal maps. It looks like the difference in curvature between the low res and high meshes are creating the wavy lines. However, since this was baked in Maya and viewed in Maya, it is using the same tangent basis and thus appearing correct in Maya and different in SD.

If you bake the map in SD, it will appear correct in SD. This is a common issue as there is not a real standard tangent basis that all applications adhere to.

I'd be happy to take a look at the scene file if you can upload here.

Also, take a look at this thread that discusses wavy line issues with normal maps

http://www.polycount.com/forum/showthread.php?t=81550

Cheers,

Wes
Head of Substance Demo Art Team
the3dninja@adobe.com
Twitter: The3DNinja

If you want your normal maps computed in Maya to render without such distortions in Designer, you need to :
* make sure that the tangent frames (TBN) are saved when you export your mesh (which implies that you use a .fbx file to export the mesh, as .obj files can't contain tangents)
* in Designer, un-tick the checkbox "Always recompute tangent frames". This is the default setting but you may have changed it by accident. It is in  Tools->Preferences...->Editors->Mesh

As Wes said, the problem comes from the fact that all programs need the tangent frames to "decode" the normal-maps, and there is no standard way to compute them.  Maya uses one, Max another, Unity yet another, etc.
At the moment, Designer can either use the tangents provided in the mesh (if any) or recompute them (if none, or if the aforementioned checkbox is ticked). When recomputing the tangents, we use the same algorithm as in Unity. We plan to add options for using other algorithms in the future.

That's the info I was looking for!
Thanks!

another useful option for custom tailored normal maps is handplane3d, take a look here: http://www.handplane3d.com/

there is also some nice information on normal mapping in general on the handplane website