Michael, thank you very much for your recommendations and for your suggestions !

> But with rendering as opposed to modeling there can still be tolerance issues in the animation program as well for stuff
> like bias factors in ray tracing where the start point of a shadow ray has to be moved slightly above a polygon
> so it doesn't hit the same polygon it's coming off of and result in self shadowing.

Thanks for reminding me the existence of the "Trace Bias" involved in the calculations of the shadows inside of ray-tracing software. :)

> I guess I'd recommend only modeling the spaceships in a CAD program like either MoI or Rhino,
> and create the planet only inside the animation program and not in CAD at all.
>...
> I'm not sure which way would be the best, you'd probably have to try a couple different ways.

I'm going to do what you suggested in order to investigate the different approaches, and to experience at first hand the different results.

Thank you for all, and have a good night.

Marco.