Missing faces when offsetting a polysurface?

Hi all,

I have imported a .STEP file into Rhino as a polysurface and I am trying to offset it by 2mm. Unfortunately, it has many small fillets, which I know is a bit of a worst-case scenario for offsets. Rhino is able to handle most of it, but leaves a few missing faces scattered about and some non-manifold edges. It’s too many to patch by hand, so I wanted to get suggestions on how to correct or avoid this issue.

It’s my rudimentary understanding that this problem occurs because each face of a polysurface is offset individually (correct me if I’m wrong). Is there way to turn my model into a surface? It doesn’t seem easy given it’s a non-native polysurface. Any other ideas?


offset surfaces.3dm (13.0 MB)

Hello - can you post an example file that shows this?


Yes, I’ve added the file with the offset applied.

Hello -You can patch up/simplify the edge surfaces with Cap followed by MergeAllCoplanarFaces, but
it looks like the more difficult holes to fill are where the face offsets to a self-intersecting thing -

I do not have a good suggestion for dealing with those quickly - looks like a lot of work, to be honest.


hmm, okay, thank you!