Transformation with Cage to create a relief perspective?

We want to create a relief perspective by Rhino, where a box have to be transformed in a truncated pyramid (vertical):

Therefore we thought that the cage function could be a wonderful tool for it.
But there are differences when we use “cage” or we construct it “by hand” with Rhino.
We are wondering which kind of transformation is done by “cage”?

Hoping somebody can help us!

Try the command Taper.
Ciao Vittorio

It depends on the point count given in each axis of the cage. I like using CageEdit with only two rows of control points in one axis to allow for linear edits. Your graphic above also seems like this might work well with Loft between rectangular curves.

Thank you, but we want to use the cage command, because we want finally to put objects in the box which are then transformed in the same way as the box.
We managed to transform the box to the truncated pyramid by the cage command, but the objects we put in it had not been transformed in the same way, there are some differences according the constructing method. That’s why we are looking for the kind of transformation, which is done by the cage command.

Thanks for the extra information. I emailed you back through tech support as well asking for more clarification on your manual process versus the use of CageEdit. Just to be clear, you are using CageEdit right not Cage? Cage will create a control object but you need to then use CageEdit to associate the control cage with another selection.

Hi Cleopold, I used a combination of Scale1D and Taper (Infinite = Yes) in the right view on the smaller box and the outer box together and I arrive at the exact same answer as CageEdit. No doubt there is a piece or two missing in my understanding of what you are doing to get the reference points though… the vanishing plane distance and sight distance seem not to be in the right ratio for this to work as (to me) it looks like it should.