Different rendering of normal map between blender and substance painter?

chopsuey · Nov 2021

edit: Problem solved

Hi, I did all my textures on painter, I bake the normal map on my low from a high with bevels.
On painter everything looks good so I'm doing my textures and exporting everything.
But on blender the result is awful

I then decide to test a triangulation and the result is much better but not perfect
then I test to remake the bake of my normal map from blender and there the result is almost perfect (as good as what I saw in painter)
Then I try to import this new map in painter to see what it gives and it's as bad as the painter map in blender (after triangulation)

you can see here the minor differences between the 2 maps:

My conclusion is that the two programs do not bake in the same way and their way of baked is well rendered by their own engine but is not necessarily good elsewhere?

poopipe · Nov 2021

To get a normal map to look the same in two different renderers you need to make sure you're using the same tangent basis and that there is no difference between the mesh you bake to and the mesh you apply the normal map to. If you're going through an intermediate format like FBX you must endure that you're passing tangent and binormal information across correctly

Painter has the (possibly default) option to use mikktspace tangent basis which is pretty standard (unreal and unity use the same). I think Blender also supports it so with the correct export/import settings you should be able to get them to match very closely

chopsuey · Nov 2021

Thank you for your answer I don't know if I understood everything I don't really understand what tangent space is but while searching i found an option on substance painter "compute tangent space per fragment" and now my exports are identical in blender.
But I didn't touch anything in the fbx export.
I tried also to import it in sketchfab to see and it's ok so thank you it solved my problem

Gorion103 · Nov 2021

Maybe You exported Normalmap in wrong format (DirectX vs OpenGL) for blender and You have to invert Y channel to render it correctly.

chopsuey · Nov 2021

Gorion103 Thanks for your answer but no that was not the problem, I export well in OpenGL, the problem is solved it was the tangent.
There is another easier way to do this, use the rgb curves and reverse the green curve

Image: https://us.v-cdn.net/5021068/uploads/editor/8q/hbf8sjw6s8dl.png

gnoop · Nov 2021

We don't use Unreal or Unity but last time I tried it in both of them, mikt or not mikt, recalculating tangents and binormals or importing them, they still can't render those normal map gradients perfectly ,especially on reflective surfaces . So IMO it 's better to get rid of shading gradients before you bake anything. By proper smooth groups , vertex normals editing etc.

Or does Unreal deal with normal map gradients perfectly already? That would be a great achievement for sure?

poopipe · Nov 2021

the per-fragment calculation helps but none of them are 100% perfect - precision is a legitimate issue when dealing with game assets in terms of both textures and mesh information.

if you throw enough data at the problem it'll go away but you can't do that cos videogames

AdrianoRegino · Oct 2022

https://polycount.com/discussion/comment/2762303#Comment_2762303

Nice you solved this, I´m having the same issue. Do you mind telling how did you fixed the tangents?

chopsuey · Oct 2022

https://polycount.com/discussion/comment/2773431#Comment_2773431

Hi, In substance painter in edit>project configuration I checked an option called "compute tangent space per fragment"

I also recommend to triangulate your 3D objects before exporting (and keep the same triangulation for all the 3D engines you want to use this texture)

In blender I use the triangulate modifier, very practical.

Different rendering of normal map between blender and substance painter?

edit: Problem solved

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