UV import issues (projecting stretched lines between vertices)

[eknightGER]

I hope I do not duplicate this topic, if someone else had same issue/solve, please redirect me.

Problem description: I am exporting from Blender to FBX or OBJ with a texture Atlas that shares UVs from different objects. Importing the OBJ the UV creates the shown stretched lines which seem to be connections between the vertex representing two borders of two islands where I set a seam. Is there anything I can do to make this go away? (It messes AO bake up as well). THe UV islands are properly imported (same as in Blender) and all position / coordinates are the same - only those stretches appear. This is not the case for all and seams to be persistent for atlases. I will try to merge the objects and see if the same issues remain importing with a single UV.

But maybe there is a fix for this and I simply do not know it? Thank you for your help.

[eknightGER]

The issue persists with even a single merged object both in FBX and OBJ export. But I found that it seems to be the bevel modifier in Blender creating UVs that are funny while the modifier is applied. A solution could be to texture without the modifier and reapply the texture in Blender. I will check that and report back whether successful or not.

[eknightGER]

RESOLVED:

I can now confirm that the issue stems from the fact that if you export objects from Blender that have a bevel modifiert applied naturally change / distort parts of the UVs if the modifier is applied while exporting to FBX or OBJ because you change the mesh geometry applying the bevel without changing the UV map accordingly. This leads to shown artifacts in SP; this is not an SP issue, nor a blender issue, but workflow based. There are a couple of ways to address it:

• you can export without the Bevel modifier applied (remove before exporting) to allow unchanged simple UVs be processed correctly in SP (pro: easy; quick, no UV reshaping required; Blender based non-destructive modeling remains intact; con: no rounded edges in SP considered while texturing) - here need to check how the textures look beveled as backed hard from SP
• you can apply the bevel modifier and redo the UVs based on the final geometry (pro: solid workflow with edges in SP, high quality output; con: destructive workflow in Blender, requires redo of UVs)
• you can try build the UVs for the model for all bevelled edges as seams - this partially works, but has pitfalls (pro: non-destructive and no artifacts; con: does not always work, needs multiple iterations between Blender and SP to get right)
• you can create two models in blender and bake the normals of the bevel applied high poly to the non-bevelled low-poly (pro: should remain fairly non-destructive, easier meshes, con: needs baking and handling of a lot more meshes)
• you can try check for artifacts and either ignore them in case of low impact or try to move the UV islands to have artifacts not cross other UV islands. (pro: avoids all the other work; con: hard in atlas modes, requires iterations)
  

If anyone has any other solutions, please let me know.

[Sbstndc]

In my case y have this problem(pics).

[ColinCW]

In my case y have this problem(pics).
...

I am also having this issue. Ended up reverting to 2.1 for now and all is well.