UV Seams in Blender to Substance Painter?

Hi all. I’ve been stuck on this problem for a couple of days now. I brought my issue on both the Allegorithmic (substance painter) subreddit, and their official forums, with not a single response! I’m wondering if the issue is actually with Blender, and how I’m transferring/prepping/saving my meshes – so I’m posting this here now.

Whenever I bring a model into Substance Painter, and bake the low poly with my high poly mesh, I get these horrible seam lines where I had cut the UV. They become incredibly apparent whenever I call on the curvature map to do something, i.e.- create a masked fill. I tried near every combination of bake setting but nothing seems to work. Tried trilinear projections, per vexel, etc. … nothing. When I export my meshes from Blender, I make sure no edges are marked sharp. I export both the high and low poly meshes as fbx. I made a completely new mesh just in case it was a problem with my file, but still had the exact same issue along my UV seams.

Including reference image. I appreciate any and all suggestions. Thanks.!

So when it comes to baking, for the low poly mesh, you should be marking all of your UV seams as sharp, and only the seams. Not doing so will result in nasty visible seams in your low poly mesh. Using one single smoothing group (no sharp edges) is an archaic practice and should be avoided.

That said, I really can’t tell if that is what is going on in the image you posted. You would be seeing ugly shading errors in the normal map if it is. That looks more like an issue with the shading/AO not blending in correctly with the next UV shell. But you should still be marking UV seams as sharp regardless.