Hi andrew - when you export N-gons to Modo, Modo will still triangulate them internally and actually renders the triangles.

It looks like probably in your case there Modo is generating a little skinny and maybe even reversed triangle on those particular N-gons.

I don't remember if there is a way to see or adjust the N-gon triangulation that Modo creates for the N-gon, but if there is a way to examine it take a look there and you might see that there is a little triangle there where you have those skinny render artifacts.

If you crank up the tessellation density a bit more then probably those areas will decrease in size to such an extent that you won't be able to see them.

Otherwise if that problem persists, I guess that you will have to use the "Quads & Triangles" output from MoI - MoI's triangulator is set up in such a way to try and avoid making little triangles along the far outside edges of N-gons (where there are things like 3 points of the n-gon nearly colinear like you have in various spots in your results here), and so that's why you get different results when exporting out from MoI as triangles.

It is possible to occasionally run into other problems with N-gon triangulation in Modo as well, but usually it is fairly rare though.

If you do crank up the tessellation density it will probably help you as well though, because when N-gons are slightly rougher and a little bit more twisted and non-planar it becomes more likely that Modo's N-gon triangulator might accidentally make a reversed triangle in a nearly colinear area.

I think that most people are exporting at a somewhat higher density than what you are showing there and you might try that to see if it helps if you want to keep things as n-gons rather than exporting triangles out from MoI.

- Michael