Hi,
When importing a model with a normal map in unreal I get these seams in the normal map.
I thought it was caused by the mip maps, but when I turned them off, nothing changed.
When I import the model in unity3d it doesn’t have this problem as shown in the image below.
In both programs, I imported the normals from the fbx and calculated the tangents.
Does anybody have the same problem or does somebody know a solution for this?
Thanks.
Looks to me like normals are getting flipped. Not sure how UE4 and Unity handle Flipped UVs, but you might wanna check in what ever App you used to create the model.
Hi ,
Thanks for your quick reply.
I made the model in maya and there are the normals and the UVs not flipped.
Try to invert Y axis(Green channel)
I did, but it looked even worse.
Looks like maybe a smoothing error with the mesh, check your smoothing settings when the mesh is imported. It needs the same smoothing applied as what the normal maps were baked to.
Did you bake it from a high poly? If so, then your object normals need to be exactly the same exported to the engine as when you baked.
It does look like the object has split normals on some vertices. Make sure that all the edges are smoothed in maya or every polygon is on 1 smoothing group in max or blender. That of course depends also on how you baked the high poly normals.
Yes I baked it from a high poly mesh in maya. The normals of the lowpoly object where all smoothed when I baked the normal map and I also exported this lowpoly object.
In unity I import the normals from the fbx and that is working. In unreal4 I chose “import normals” in the import settings of the static mesh and I checked “Recompute normals” off in the LOD0 settings of the static mesh.
Maybe Unreal still recomputes the normals somehow. Could there be another setting for your normals somewhere?
Check that UE4 doesn’t re-compute smoothing groups on mesh import, as it’s switched on by default.
is that baked light? Lightmap might be too low resolution and the UV islands will be causing some lightmap errors. Posting the UV layout (for both normal and lightmap) might help get to the problem source, if it’s not baked lighting ill go back to my hole 
I switched off the re-compute smoothing while importing. If I look at the object without a shader there are no hardedges.
The static mesh is set to movable so assume it isn’t calculating lightmaps. back to your hole! 
I uploaded the fbx with the textures to mega. If someone could check it out if they have the same problem that would be really great.
I found the problem. It was as zeOrb said, I need to invert the green channel. I inverted the green channel in the shader, but apparently that doesn’t give the right result.
You need to check the flip invert green channel option in the texture settings.
Thanks for your replies.
I have exactly the same problem…rock mesh sculpted in zBrush, lowpoly made with TopoGun, Normalmap baked from the highpoly in Maya. As soon as I import the rock to UE4 I have those ugly seams.
How did you manage to invert the green channel on the normal map? In the UE4 TextureEditor I don’t see this option…please help me out in case if I’m just blind like a mole.
Hi Lestat,
You can flip the Green channel during import of the texture or once the texture is imported you can open the image up and in the details panel to the right you can select “Flip Green Channel.”
If you’re still having issues feel free to ask any questions! 
Tim
Thanks Tim,
I didn’t notice that I could expand the texture menu…I just saw the upper 3 entries.
Thanks, now everything works fine
Thanks guys! This fixed my issue as well.