Before assuming I haven't read and searched for others with the same problem, I have, also with no success. I've been having this issue for days and this is after I've read many FAQs going over normal baking and what not. I'm fairly new to baking normals, as I've only been doing it for a few months. To show this issue, I made a simple box, cut it in half, welded so it matches UVs, then baked in xNormal... so yea I cant figure out why I get this slight seam. Thanks for the constructive advice ahead of time.
Replies
Cut mesh in half
UV'd that half
Mirrored the mesh and welded
The offset the new half 1 UV space over.
Baked in a cage, (tried cage bake in both xNormal and 3DS MAX)
if not, don't worry about it unless it looks bad in your final presentation app.
Did you weld the new piece to the old? If you did and then broke it apart again your normals won't match and it will give you a seam. Apply an edit normals modifier to it in max and see how the normals look and how they change as you weld and unweld things. If they change after you've baked its going to cause problems.
You could try creating a new piece next to it without welding it, then create a welded version and align the normals of the split version to the normals of the welded version.
Basically your normals aren't matching at the seam and they need to match perfectly for it to work.
You're using max, how are you doing the mirroring? Manually? Mirror modifier? Symmetry modifier? If its not symmetry, try that.
Also pop on an "edit normal" modifier to see what max's normal and tangent data looks like to see if the error in vertex coordinate calculation is in max or in the export process.