Hey,
I have a rather simple file, but my surfaces already seem to glitch out. I know this issue from rhino 7 and also older versions, where it occasionally “destroys” the rendered mesh. The edges are correct though.
It seems the longer the file is opened, the more surfaces become corrupted, even though I didn´t touch them.
EDIT: I also have my nurbs mesh quality set to the highest already
There are (possibly) two things going on here:
One is your meshing settings. For help on that look here.
The other possibility is that you have surfaces with G1 (tangent) internal joints which the Rhino mesher does not like. You can select the surfaces and run the command _DivideAlongCreases _SplitAtTangents=_Yes and see if that helps.
Otherwise, please post a sample file here showing the problem.
In the final modelling i would build it like you proposed, this was just a quick shape exploration, but even then i think it should work, since its a 4 point-curve that is only linear extruded.
But thanks for the tip, if i run into this issue again maybe that would solve it then 
That did not do the trick unfortunately, here the surface.
Rebuilding the surface works, but that only works with the flat one, with more complex shapes it wont work.
It would be good to know what the root cause is so I can avoid this in the future
I do not have the first faulty surface anymore, but the 2nd one:
Surface Issue.3dm (68.3 KB)
Thanks for your quick reply!
Hi Basti,
Yes of course, it should.
I don’t really know if this is what causes the problem, but in general modeling those two surfaces separately seems to be the “right” way to o it.
It seems easier that way too, but of course I don’t know all the circumstances.
Just checked your surface: The check command shows it is invalid with some problems on tolerant edges.
In these cases DupBorder->Untrimall-> then re-trim with the border curves usually solves the problem and indeed in this case it does too.
Surface Issue-solved.3dm (68.5 KB)
Yes that worked, thanks!
I only wish this would not happen at all 
