Blender Rendering Glitch

I’m rendering an animation and I noticed that there’s a weird problem with the top rotors on this helicopter model.

I’ve double checked that my mesh isn’t overlapping with anything. I’ve already recalculated and flipped the normals. None of those things have worked. I’m using the Blender Internal renderer in Blender 2.71. How might I be able to fix this?

Sorry I can’t post my .blend file. It wouldn’t show up in Dropbox.

Upload to and tell us download link

I tried twice, but it failed both times even though it’s smaller than 30 MB.

Hm, save file with new name and delete all except top rotors and post this file.
Or append top rotors in a new file and up this.

Cheers, mib

Looks like you’ve got either overlapping faces or overlapping objects.

I made sure that there were no overlapping objects. However, I might have overlapping faces, like you said. If this really is the problem, how can I fix it?

Strangely, I can’t see the problem when the rotors are in this file.

EDIT: I stupidly forgot to mimic the lighting used in my original file. You should be able to see the problem now.

Looks like doubles.
Select all in edit mode + W > Remove doubles.

Overlapping faces

You also have an edge split modifier that you haven’t enabled for the render view (look in modifier settings)

It didn’t work. Do you think I need to turn up the Merge Distance or something?

Right. I turned that off to see if it would fix the problem. After that, I forgot to turn it back on.

Okay, so I tried to remove the doubles again with the merge distance turned up and the rotors now look a lot better. However, as you can see, there are still some black spots left and removing the doubles any more would take away too much of the detail. Any other ideas?

Those blades are a triangulated mess, and you have a bunch of vertices merging into one another. I fixed some of them by mostly getting rid of edges and rejoining vertices where they should be, but you’d be better off modeling new blades

This right here is just ridiculous:

This usually happens when importing something from another program, so it’s not your fault. It’s just up to you to either fix it manually, or make new blades. Blender’s Edge Split and other modifiers aren’t really going to help much here, and it’s not Blender’s fault either, it’s just really bad geometry. :slight_smile:

Hmm…well, the model’s not mine. I suck at modeling and I think that doing it manually would take too long, so my hands are pretty much tied. I guess that the rotors with the doubles removed should serve my purposes pretty well. The motion blur in my scene will probably hide the errors anyway. Thanks for the help!