SelectionPoint error on RevSurface's isocurve

When picking the isocurves of a RevSurface for Custom.GetObject, the ObjRef’s SelectionPoint location seems to deviate from the actual point picked between 45° intervals. The errors can exceed both the ModelAbsoluteTolerance and ModelAngleToleranceRadians.

To see this, run (627 Bytes) on
Study_SelectionPoint_on_RevSrf_IsoCrv.3dm (94.4 KB)
and pick points on the isocurves near the red and green points of the orange RevSurface sphere.

Location errors are greatest near the red points, whereas picking at the green points doesn’t show an error.

Doing the same on the blue NurbsSurface sphere doesn’t produce these location errors.

I did not find similar errors using Custom.GetPoint with _OnSurface snap.

This occurs in V5, V6, and the WIP.

Thanks @spb, I’ve add this to the pile.

– Dale