Crumpled Normals problem

sharsein

So I'm sculpting dragon nunchuks, and I'm getting really frustrated with baking normals. I got the low poly to look ok in Maya (top left) but when I bring it into Substance Painter and apply a metallic substance, it looks like it's made out of crumpled tinfoil, especially around the eyes. I want it to look more like the highpoly (bottom right).

Is this a problem with my UV layout (bottom left) or topology? What would be a good way to approach retopping/baking normals for a sculpture (organic form, hard surface treatment) to avoid the crumple problem?

aharmlesspie

Invert the green channel of the normal map.

huffer

It's tangent space difference, Substance painter uses mikk (like in UE4 or xnormal), Maya has it's own. So the safest bet is rebaking in xnormal (don't forget to export your low without tangents and binormals, and in xnormal enable compute binormals in the pixel shader under tangent basis options).

Bartalon

You can also set your project settings inside Substance Painter between OpenGL and DirectX. This will interpret your normal maps correctly without having to manually invert any channels in Photoshop.

sharsein

Thanks all! Inverting the green channel worked. I will eventually want this to go in UE4, so keeping DirectX makes sense.

huffer wrote: »

It's tangent space difference, Substance painter uses mikk (like in UE4 or xnormal), Maya has it's own. So the safest bet is rebaking in xnormal (don't forget to export your low without tangents and binormals, and in xnormal enable compute binormals in the pixel shader under tangent basis options).

I'm a little confused what you mean by tangent basis options stuff. From googling, I guess the obj format automatically exports without tangents and binormals? What does computing the binormals in xNormal do? I used xNormal 3.18.1 which doesn't have the tangent basis options (installing more recent version now though).

huffer

3.18.1 should have the option, is under the power plug icon - tangent basis calculator - mikk -tspace - configure. If you bake for UE4 or Marmoset, that option should be on, and your bake is synced for UE4 (and it will not look good in Maya). If you export an obj (yes, it doesn't export tangents and binormals) and you bake in xnormal, it will use mikk tangent space, if you export an fbx with tangent and binormals on, it will use whatever tangent space came with the mesh (like Maya). So you will have some shading issues if you baked in a different tangent space than your target engine, mostly around soft round shapes (if you use lots of hard edges there'll probably be less artifacts).

sharsein

Ok this makes sense. Thanks!

huffer wrote: »

3.18.1 should have the option, is under the power plug icon - tangent basis calculator - mikk -tspace - configure. If you bake for UE4 or Marmoset, that option should be on, and your bake is synced for UE4 (and it will not look good in Maya). If you export an obj (yes, it doesn't export tangents and binormals) and you bake in xnormal, it will use mikk tangent space, if you export an fbx with tangent and binormals on, it will use whatever tangent space came with the mesh (like Maya). So you will have some shading issues if you baked in a different tangent space than your target engine, mostly around soft round shapes (if you use lots of hard edges there'll probably be less artifacts).