Strange offset results in Rhino 7

Take a look at these 3 surfaces. Offset them all together and notice the results of the magenta surface.


This isn’t the first time we’ve seen this. Interestingly the Rhino 8 WIP also offsets incorrectly, but takes a lot longer to do it.

Here is the file if anyone wants to give this a try:

Strange offset.3dm (233.4 KB)



Hi Dan, checking it, thanks.
@DanBayn - that surface has ‘issues’…
Edge Tally:
16 boundary edges
Edge Tolerances: 0.528 to 2.005 <<<<< Here
median = 1.644 average = 1.453
Vertex Tolerances: 0.527 to 2.007 <<<<< Here
median = 1.556 average = 1.326

If you RebuildEdges, you’ll see how far off it is and it will all work again.

It is also a large underlying surface, I’d shrink it if there is no reason not to.


Hi Pascal,

Yeah, there’s something bizarre about that surface. Look how it comes into Fusion (there’s no surface offset in this image)

I tried to shrink it and use RebuildEdges but it’s still pretty ugly (in Rhino 7 anyway, I didn’t try the WIP).

Thanks for looking into it,