Cage from surface

Is there anyway to generate a cage from a surface? It seems to me that a cage has U,V, and W points. And extruded surface could have the same- theoretically.

I’ve simplified my geometry for this example. Let’s say I have a set of geometry that is oriented to a surface in a particular way and I want to taper it relative to the length of the surface (not linear like the taper command). I could see that if I had a cage with a UV that matched the base surface and a W height that matched the height of my geometry, that I could easily morph my geometry relative to is position on the surface. How can I get a cage to match the shape of the surface?

Is there another better approach to doing something like this? Tapering is only one conceivable morphing effect- what if I want to twist along the length of the surface? In my situation, it is not necessarily multiple geometries along a curve and the geometry is more complicated (currently the surface is flat, but that may change). I know I could script a solution in grasshopper, but I am trying to use Rhino more. If only there was something like Surface Box (grasshopper) where you could edit its control points.

160509 Temp.3dm (91.5 KB)

Yes, all objects, where you can turn points on, can be used as "cage edit object"
Cage Edit -> Select Captive Objects -> Select Control Object and click on surface -> enter and new, this surface is your cage edit control object

Thanks, this helps me turn the surface into a control object, but it is still flat. When I extrude it to get something with thickness, I can’t seem to convert the polysrf into a control object. If I want to taper the cubes, I need some points in the W direction.

Hi Lawrence,

You might be able to get what yoy want with the Command FlowAlongSrf (with History for inbteractive editing):

flowalongsrf.3dm (319.7 KB)

HTH
-Willem