Intersection Problem

In the attached file I have two polysurfaces.

One passes completely through the other. Yet when I intersect, I get two disconnected curves, when I would expect one curve.

Why is this?

Problem Intersect.3dm (3.1 MB)

Extract the contours of the purple flat surface 25. Create a new surface 41. use the “intersect” 33command.
Alternatively, explode surfaces 49, cancel all cuts26 (keep all cuts on), rebuild the surface43 (4U 4V G3 U V) use “intersect”, cut the surface.33


This looks like an intersector bug in V5, it has been fixed in V6. That being said, your purple surface with the round hole has 226 points in the V direction, which is completely unnecessary as it’s a planar surface… Would be advisable to fix that in any case - just DupBorder, delete the original, and use PlanarSrf to recreate it - then the intersection will work fine in V5.