Hi Keith - here's an example showing the difference that using vertex normals will make - I loaded your Crab.3dm file and exported it out using the exact same settings you show above (the somewhat coarse default angle = 12), and loaded it into Cinema4D and rendered it there - notice that all of those glitches that you pointed out on the claw are completely gone with the same polygon mesh density.

If you want to get better looking results you will need to use a rendering tool that works better with CAD originating data and can load all the information from the .obj file including vertex normals rather than skipping the vertex normals and just having them created by averaging polygon faces which is what creates those glitches that you pointed out above. Simlab composer would be good choice to use because it's pretty easy to use and not as expensive as many of these other fancier rendering and animation packages.

Anyway here's what your same data (with same density as you used above) looks like rendered in Cinema4D:



- Michael