Import Mesh Error: Bi Normals Are Nearly Zero, Tolerance of 1E-4

Hi everyone, I met some problem when I import my mesh from Maya to UE4, it shows the error: nearly zero bi-normals which can create some issues when I import FBX file. Then I clean up my object in Maya, combine all vertex, and clear history, and export again, but this time, instead of checking smoothing groups and smooth mesh when export in maya, I also check the tangents and binormals, and select the import normals and tangents in FBX import editor in UE4. BUT this time, two errors bump up: nearly zero bi-normal and nearly zero tangents. I’m totally confused now, does anyone know what causes these error and how can I fix it?? thanks in advance.


Can anyone help here? I am having a similar issue.

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This happens if you literally import a cube.fbx from blender. Seems to be a very common problem with no answers anywhere.

I was getting the bi-normals are zero message & when importing an obj file created from Maya, zbrush or Blender my meshes were coming in shredded & riddled with holes. When I unchecked the “remove degenerates” box in the import menu that comes up the meshes came in normally

maybe the mesh is too small, my mesh was tiny in maya, scaled two/tree times its size and it worked, also I unchecked smooth mesh

In my work I have faced this error many times, in most cases it can be eliminated by importing meshes into Unreal by turning off one value. As I understand it happens because the model has very thin polygons and the Unreal removes normals value for optimization (it perceives the model as a highpoly).

Sometimes there are cases when this doesn’t help and normals are still broken. I encountered a case where I need to triangulate a model in engine and bake it in Marmoset and later paint it in Substance, in which case everything is ok in engine and Marmoset, but normals are recalculated when importing into Substance. This happens because of geometry errors. I noted several reasons for this, such as lamina faces, nonmanifold geometry, zero-value edges, and isolated vertexes. These errors can be found with Mesh Cleanup and the Checkmate script. Good luck and clean meshes, everyone!


Having trouble importing FBX/USD of a castle. When I tried USD the materials did not appear on the mesh even though material was rigged fine.

When trying to import the FBX I keep getting this nearly zero error. “Remove Degenerates” is checked and the entire entry is sort of greyed out. I can’t un-check the box.

All what you need to do is Apply all transforms in Blender or Maya etc.

SOLVED: I have resolved this (the error produces artifacts on the normals and in general on materials application too) importing the mesh in 3DS Max and applying Mesh Cleaning in Retopology Tools. Send me mesh if you want a simple clean test. For other 3D model, cleaning up in ZBrush or other software help to correct the error