How to remove that seam line in normal map?

Hi, I’ve create a hand with a diffuse and a normal map texture, the diffuse texture is seamless, and I created the normal map texture with awesomebump.

The problem is that a line appears along the seam, I tried to use the smear tool to remove it but it only work at some places.
There must be something to do but what ?
Maybe it’s because the painting tools don’t go after the seam limit on the texture file, is there a setting to allow that ?


There’s a seam_bleed property for extending the paint after the seam limit… but I doubt it would solve the issue, as painting/smearing normal maps is simply the wrong operation.
I don’t use AwesomeBump, but it might be the case that it fails to calculate the derivatives in the seams…
To fix it, one would need to check the normal map, if the normals are continuous in the tangent space (not a simple task, i must say).

A normal map is just a texture with rgb values. Same colors means same normals, then smear tool should work.
I think my normal map is not “normalized” so that differences are nearly invisible with eyes and that the blender strength corrects it, but makes the very little difference on the seam visible.

I corrected the problem by using the clone tool (but it’s still unperfect) (I also added bleed but not sure it changed something).

That’s not entirely true!

Same colors means same normal in the tangent space. But when we transform the tangent space into world space, the same colors end up pointing to completly different directions (specially in seams).

I spent already too much time today in this topic to repeat myself, but please read this other thread about a similar problem.

You’re true but I already understood this, I simplified in my reply but the normal in an uncut mesh that has been smoothed should be the same for a same vertex and then I shouldn’t have that issue.
Then i must mean my normal are incorrect, I will check.

I corrected my problem with… clone tool, in fact I was true about the normal have invisible differences, then I connected the normal map to the color in the shader editor to only see it, and inserted a brighness/contrast box and increased the contrast, I saw all issues with my normal map. I corrected all those bas lines and everything is fine now.
Anyway, thanks for your time.