Map 2D base, extend to 3D

I have a 2D rectangle with 3D stuff over it. (For example, think of a bunch of little hemispheres sitting on the rectangle.) I have a surface in 3D which is an image of a rectangle. I would like to map the 3D stuff over the 2D rectangle into 3D space “over” the surface. That is, the x,y’s of the 3D stuff go directly to the surface, and the z’s of the 3D stuff become distances normal to the surface. (Yeah, this is hard to describe.)

I’m thinking of a command called something like “extend 2D map to 3D”. It would ask for:
(1) Select objects to map.
(2) Select “from” surface
(3) Select “to” surface.

Of course, I don’t want to work with U,V’s, they should be invisible to me. I want it to work with real distances measured on the surfaces. It could require that the “from” and “to” surfaces be untrimmed (which means that they are both images of rectangles). Options allow flipping directions (x -> -x, y -> -y, x,y -> y,x, etc)

Is there anything like this now? (I’m running Rhino 4. Did it come in later?)

Dave Golber

The command is called _FlowAlongSrf. You will need a flat rectangular surface for the base surface (not just a rectangle) but otherwise it works pretty much exactly as you describe. See the Help for more details. It was already available in Rhino 4.

Thanks much. I’ll give it a try.