Hello as you can see from the picture below:
It’s impossible to diagnose this without knowing:
If you can turn on display of those things in the mesh editor, and add a screen shot, plus a screen shot of the normal map from the texture importer and the shader, that might help someone figure out what’s going on.
Sorry what is the triangulation and tangent basis? Also if it helps, two of the megascans surfaces are doing this and its only on the top of the texture.
The triangulation is how the mesh is broken down into individual triangles. This is kind-of like “the wireframe,” except some tools show quads in wireframing, and the triangulation further splits those quads (or patches) into triangles.
The tangent basis is the tangent basis. It contains the tangent and bitangent. Together with the normal, these make up the transform basis for light vectors going into the tangent space within which normal maps are typically defined. Typically, this is calculated by taking partial derivatives of the U and V texture coordinates for the normal map texture channel in mesh model space coordinates. You can turn on displaying the tangent basis in most creation tools and in the static mesh inspector in the engine editor. When the tangent basis is wrong (or maybe even not calculated) then normal maps won’t tile well. When the tangent basis is mirrored (typically because you used mirrored texture coordinates,) then it also won’t tile right, and sometimes normals may look “inside out.”
Btw: This is why normal maps are mostly blue: the normal is the “Z” part of the tangent basis, and blue is the “Z” part of the normal map value, so normals pointing largely “out” from the surface are blue.
Thanks, I’ll have to get back to you later, but this mesh is previously a landscape, I exported it, in that landscape I did use the mirror tool could that be an issue?
Mirroring UV maps can screw up normal maps along the mirrored seam, yes.
