normal map seam issue

Urdwex

Hey I have a problem with baking my normal maps, I have a problem at the UV seams. I exported from Blender with smoothing from UV's and baked it in Marmoset. The normal problem is also visible in Marmoset. 

It's a very small error. If I look at the model in the final size, I'm not able to notice the problem. Though I would like to know what's the problem to learn and solve my mistakes.
Does anyone know what causes the problem? 

Here is the problem:


Here you can see that in the normal view distance the error isn't visible: 


And here in Blender the Vertex Normal are splitted from the UV's, also the padding should be enough. 

Noors

You've made no mistake. It's a limitation of actual bakers that causes this issue on uv splits.

In a normal map, each pixel encodes for a direction.
To prevent artefacts due to texture filtering/mip mapping, the baker extends a bit the border pixels of uv shells (known as texture padding).

But it actually just duplicates the same color/direction, while those "extended pixels" shouldn't encode the exact same direction.
What you see there is the next pixel line with a slightly off direction, bleeding because of texture filtering.
But even with a more accurate padding method, due to texture resolution/compression, this would never be 100% perfect if you zoom on it like crazy.

The only way you could actually make this less visible, would be by increasing the texture resolution. There still would be the exact same issue, but at a finer level. And it would certainly be a waste of resources as most of the time, this artefact is insignificant.

Urdwex

Ah, thank you for your help. 

Good to know that's a technical limitation.