Substance Painter- Normal Map baking Problem

Drekavac

Hi,
          I've recently finished modeling gun and started texturing. Unfortunately I have baking issues. I made my model in Blender and It seems to me that there is some problem either with topology of my low-poly model or shading smooth problem (or both). When I'm just using shade smooth option and export model to substance painter, baked normal map looks like it just baked details but with parts of just shade smoothed low-poly model (like in the picture).
This is how model looks in Blender when I use just shade smooth option all over the model.

On the other hand when I use auto smooth option (get's rid of bad looking shading from flat surfaces) I don't have this problem but I have artifacts on sharp edges.
I have no idea how to deal with it because I never had this kind of problem with baking befor. I know that it's probably problem with topology but I think it's worth it to try and ask for advice. Some of the Uv's are moved one unit out of the texture space because I mirrored them in order to get better texture resolution on model. 

This is topology of low-poly model



I know post may seem chaotic, I will provide any necessary info if needed

poopipe

That's basically fine. 

You could probably refine this to look better but it will never be perfect due to limitations in the way normal mapping works. 
As long as you have padding turned on and you have made an effort to ensure that UV seams are horizontal/vertical wherever practical there's not a lot more you can do.
Basically if you are near enough to the object to see the seam artefact, you are near enough to need a bevel in the geometry. 

huffer

That's not fine at all. First of all, make sure your low poly has either hard edges properly setup (at 90 degree angles) or uses weighted normals. This way you'll avoid gradients in normal maps. A good normal bake should look as flat as possible with 128,128,255 color, NOT with gradients. Those gradients will look bad in-game after compressing textures. Employer won't probably accept that.

Secondly, don't forget that if you do use hard edges, you need to split your UVs there, or else you will get edge artifacts like those. Also leave enough padding.

poopipe

To clarify I was referring to the version with hard edges (the last 3) which is where the OP has ended up through their own investigation.

The edge artefacts are impossible to avoid if you have a UV seam at a 90 degree  edge

As fas as i can work out the artefact is connected to the way textures are sampled/filtered and occurs when texels get bigger than pixels (*not a render programmer)

Drekavac

Thank you a lot for the advice I've managed to repair my normals. It's firts time I had so much problem with it but I'm very glad I did. I've never used split edges and weighted normals modifier in Blender (which I can see now was a big mistake, well....) In order to get better normals result I had to split cerraint parts of model into more islands to get desirable look and I guess that was one of the points to get better normals, right? 

I;ve checked model and I can't notice any artifacts on edges. There is a little bit of gradient on normals in some parts but I guess that's ok?

That's how model with normal map looks right now.