Snap to intersection of line and surface?


I am trying to drag a control point to the intersection of a line and a polysurface as shown in the picture below:

The surface is not parallel to my coordinate system. The easiest method I have found is to trim the line to the surface and use the endpoint of the line, but is there a way to snap the intersection without creating or altering geometry?

Rhino does not currently recognize the intersections of curves with surfaces as snap points… So you will likely need to create some helper geometry, or, perhaps SmartTracking can help in certain situations.


in some situations, a solution is to use the Intersect command on the line and surface… (which will give a point to snap to)

another way is to use the On Surface osnap (which will constrain the cursor to the surface) along with the Near osnap (which will find the line)… resulting in a click point at the intersection of surface and line.

You just want to be careful with that one - if the line and the surface don’t actually intersect, but are a near miss, the snap point will be the closest point to the line end normal to the surface… which may result in some inaccuracy that you might not notice at first.



I tried the on surface with near snap and found that the snap point seemed to float a little depending on where my cursor was. I think it would work well if accuracy was not a concern.

I also tried with smart tracking, but for some reason I cannot snap tracking points while dragging the solid edit points? I definitely have smart tracking enabled and I use it often. Is there something I am missing?

Edit: I was able to use smart tracking by using the move command instead of just clicking and dragging. That worked well and did not require additional helper geometry.


What’s up with this? It doesn’t seem there should be a difference. IMHO

this option to snap to surf crv intersection would be extra useful for r7