Hi Martin, it could be possible that it's kept as a kind of "analytic blend" in your first example that looks better, rather than it calculating a full NURBS surface which it needs to do for exporting to other applications. The problem is that it is also likely that it will calculate a NURBS surface result in various other situations as well like when there's an offset or intersection that needs to be performed on the analytic surface. So if there is some kind of degradation happening at export, it's pretty likely that the same kind of degradation will also happen in a variety of modeling operations as well.

In fact if it is not quite as bad in the initial display in ViaCAD that's quite a big can of worms in itself because it means you're not at all operating with a "What you see is what you get" system - that's quite troublesome if things look ok at runtime but then fall apart with major changes in surface structure and quality when you go to do some final step like export...

But also another problem though is that it's hard to see anything for sure in those screenshots that you posted due to the very poor quality of the display - notice how there is an abundance of jaggedy triangulation artifacts everywhere that you look in every screenshot - the triangulation being used to display the surface is just too coarse to be able to really see what's happening with the small details of the surface. This often times can completely disguise surface quality issues with ripples and bumps.

Think of it like this - say you have a surface that has a bunch of little squiggles in it, when viewed from the side it might be shaped like this:



But say this surface gets triangulated for display coarsely with only a few triangles say like these 5 points here:




When this happens the shaded display (which is just done purely from the triangulation) can easily look like the surface is all nice and regular and smooth, but what really happened is the triangulation is too coarse for you to actually see all the true details of the surface.


Now compare those screenshots that you posted where you can see all kinds of triangle artifacts, to this one here that I took in MoI:



Notice how in this screenshot you cannot see any trace evidence of triangulation whatsoever?

If you can't get the ViaCAD display to this same level of quality removing all triangulation artifacts, and getting to almost one triangle per pixel (or close to that) you won't really be able to say for sure if the original surface before export was actually less wiggly in some way or not...

- Michael