Hi Jason, my guess is that those rendering artifacts are probably a side effect of the surface duplication - when you get polygons stacked up on top of each other like that it can cause rendering problems with the rendering thinking that some of the polygons are shadowing other ones.

Some areas of the model seem to have even more than just 2 pieces stacked up, I just saw one spot that had 4 stacked up pieces.

It's hard to tell at this point if that duplication was in the original IGES file, or if it was some side effect that happened when attempting to join the surface pieces in the original IGES file together. One way you could tell about this part would be to turn off the automatic joining that happens with IGES importing (that's under Options > Import/Export > IGES options > "Join surfaces on import"). If you have that turned off, when you import the file do you get stacked up pieces or no stacked up pieces?



Also I've attached here a tuned up version of your sample piece, where I have removed the duplicate surfaces and have just single surfaces all joined together. Could you please test exporting and rendering this version and see if your render issues are solved with this version? If so then that would definitely pinpoint that it is the duplicates that are causing the rendering artifacts that you are seeing (most likely in relation to raytrace shadow calculations during the rendering, that's probably why you don't see them in the real-time view since its not doing shadows there), and if that's the case I can then help you to clean up the full model.

- Michael