Hi Martin,

> Do you think what you're seeing is something to do with
> exporting it as a SAT file?

No, most likely it's just that the analysis display in ViaCAD is just not detailed enough to pick up on the small sized little bumps.

I've seen similar problems in other CAD programs as well - remember that the shaded display is actually generated by creating a polygon mesh approximation of the true surface. If too few polygons are created they can actually miss little ripples and you just don't see the true surface quality.

One of the nice things about MoI's viewport display is that it puts a much denser set of display polygons up than you typically see, (including putting polygons along every surface knot line) so it is able to more accurately display problematic surfaces that other programs just kind of gloss over.


In ViaCAD if you set the object resolution to "super fine" from the default of "very fine", you can start to see the bumps a little bit more, here I've re-created your fillet in ViaCAD rather than importing it from your SAT file and you can start to see a bit of the lumps in these areas:



see the traces of those 2 vertical lines in there? Even at ViaCAD's "super fine" resolution there are actually still not enough polygons being generated to be able to see it properly though. But you can see it a bit easier if you move the view around with the highlights running through that area.


It's very unlikely that ViaCAD would produce bad SAT output, because SAT is the native format of the ACIS geometry kernel that ViaCAD uses.


- Michael