Hi Dirk,

> It seems Moi or c4d uses a whole triangle for the edge of the fillet.

MoI is making an n-gon there, there are no triangles involved at MoI's export time (unless you set that option of course) - it just happens to be an n-gon that has several points that are near to being colinear with one another as they follow some curvature.

C4D will take that n-gon and then break it into triangles for display and rendering purposes, and it's that triangulation process that is probably not going quite as well as you would want.

The way that would be good to triangulate it would be like this:



That gives triangles that kind of more gradually spread across the n-gon, instead of the previous case that I showed where you get 2 big triangles and one degenerate one. But unfortunately it looks like you are getting that bad case in C4D's n-gon triangulation.

- Michael