The Match command has the PickPoint option to match the end of a curve to to another curve at a selected loction, Several revisions are needed. For reference, the command line history when using Match with the PickPoint option is:
Command: Match
Select open curve to change - pick near end to change
Select open curve to match - pick near end to match ( SurfaceEdge MatchTo=CurveEnd ): MatchTo=PickPoint
Select point on curve to match ( SurfaceEdge MatchTo=PickPoint )
1 The point to match on the target curve cannot be picked precisely. Osnaps do not work for the location selection, and the point cannot be adjusted after the initial pick. The target curve selection and the point picking are a single step. The location where the target curve is clicked is also the point at which it will be matched.
Selection of the target curve and selection of the point for matching need to be two distinct steps. Osnaps need to work for the location, and the ability to move/correct the picked location before completing the second step is very desirable. This is how the the SurfaceEdge option of this command works. Since the interface for another option in the same command already functions as desired it should not be difficult to add it to the PickPoint option.
The inability to precisely pick the point using Osnaps results in errors in the location of the end of the curve, which in turn can result in problems later on.
A work-around for precise matching is to either split the target curve at the desired location, or extract a subcurve with an end at the desired location, and then use Match with the default MatchToCurveEnd with the split curve or subcurve as the target.
2 A “Flip” option is needed when using PickPoint with Tangency or Curvature matching. Currently the orientation/direction of the curve to be changed appears to arbitrary and cannot be controlled by the user.
If the match is in the wrong direction a work-around for precise matching is to either split the target curve at the desired location, or extract a subcurve with an end at the desired location, and then use Match with the default MatchToCurveEnd with the split curve or subcurve as the target.
3 The MatchToPickPoint option needs to be documented in Help for the Match command. It is not included even though this option was added way back in V6. Match | Rhino 3-D modeling
Ideally, the current interface for Match would be replaced by an interface similar to the BlendCrv interface. That interface addresses all of the issues above plus allows for adjustment of the shape of the cirve within the selected levels of continuity.
Bonus: The Match PickPoint option is not documented in Help even though it was added way back in V6. Obviously this needs to be addressed.
Match | Rhino 3-D modeling