Hi Keith, so in order to get a smooth render, there is a piece of information that is part of the mesh called "vertex normals" which is important to get used in order to avoid shading artifacts.

Unfortunately I seem to remember that in recent versions of Carrara they stopped reading in this information and without the vertex normals being used you will tend to get shading artifacts like you show. I don't think it used to be a problem so it's something that they changed in Carrara at some point and after that change it is not very good for rendering CAD data anymore unfortunately.

If you can find any import options for the Carrara import, see if there is anything labeled "Vertex normals" which you can enable, which would then likely solve the problem.

Blender has also had the same problem but I think it may be fixed up in the most recent version of that. I'm not entirely sure though.

Pretty much every other rendering program than those 2 will work better. You might try the demo version of Simlab composer and see if that works better for you.

For all 3 of these programs (Blender, Carrara, and Simlab composer) you would want to use OBJ format for saving out from MoI, with Output : "Quads and Triangles".

But I think it's likely that if you try a different rendering program that does support reading vertex normals from the .obj file that would get you higher quality shading and avoid those problems.

- Michael