I get the sense that that's exactly how these were created. The transition from ground view to aerial view gives no hint of a full-sized aircraft's ideal lift-off point.

These are probably all hand-stitched though, with photo manipulation tools, and not programmatically generated, since it seems to be a one-off project inspired by the surrounding environment and terrain. It's likely possible to program a utility that creates these, as a follow-up phase to the general concept.

Yes, and you can even get similar results (of room-scale objects) by mis-using the panorama photo feature in the iphone camera app. Presumably if you strapped it to a drone with a rotatable arm, you could get something like this.

Couldn't you just as easily use a balloon on a tether?