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I was importing some Wavefront Object files with bpy and noticed that the textures/materials were going berserk. I know the .obj files are good as they come from a large dataset used for research.

I wondered if it was just the Python interface, but sure enough, it still happens when I import it though the UI.

My best guess is that the surface normals are incorrect since it seems to happen both in solid object view and textured view. It may also be the UV coordinates being registered from top-left instead of bottom-left or something though. Any ideas?

Solid View: Blender solid view of object

Textured View: Blender textured view of object

The Windows 3D Builder app renders it just fine though: Windows 3D Builder object import

Chris Watts
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The issues you find here are a combination of three distinct problems all related to the quality of the original models, and most likely not caused by Blender or import method.

  1. You model has bad topology - Most likely caused by being apparently made by some sort of NURBS or Solid modeling application, or maybe abuse of Boolean operations. Not really easily fixed unless you remake it from scratch

  2. Your model has overlapping geometry - Particularly on the rifle handle there seem to be some duplicate or overlapping almost coplannar surfaces. You may try to clean that up by hand

  3. Your model has inconsistent normals - Easily fixed by selecting all your faces in Edit Mode and pressing Ctrl+N.

Also have in mind that this has nothing to do with materials or textures, as OBJ doesn't really support proper material importing or exporting

Duarte Farrajota Ramos
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  • So, what do I do if there are hundreds of thousands of these models - i.e. I can't fix them by hand? – Chris Watts Apr 28 '17 at 05:51
  • If you are proficient at coding or able to do some scripting , you may try to write a python scrip that automates some of the required steps, but don't expect miracles. – Duarte Farrajota Ramos Apr 28 '17 at 13:06
  • Actually, this is not the case. I suspect it's a bug with Blender >=2.77 as my laptop, running Blender 2.69 has no problems. – Chris Watts May 09 '17 at 15:28
  • I have a similar issue with the same dataset. but for me downgrading did not change anything. For me the textures are not incorrect, they are just not visible at all, most things are just standard grey. – McLawrence Aug 27 '17 at 13:28