Creating a hovering layer over this then, pasting your new art selection allows you to visualize the 3D placement of the object in a virtual space. Sounds so technical.
Example of canvas in use.
The object is on a layer above the alignment canvas and it is centered with the floor. You then paint the canvas black or white. And crop from the top down only.
Example of a finished item.
For more detailed explanation and examples of usage see my aligning images video tutorial in the Art-Tutorial section of forums.