Bakster
Cool pic, Capn. I would love to watch how this is done.
Relatively boring, actually.
You build up the furniture one bit at a time. With ACAD's Rednder 1.0, you had to mind which way you extruded things, as the materials "followed" the extrusion. Anything you wanted to render differently needed a unique Layer.
The windows are a bit of a bear. With R14 you could not embed a Void into the stucture of the Block to cut the wall geometry; so the openings had to be cut by hand. Then a windo block installed in the void.
To make a painting, you modeled up the frame, and added a bit to be the image.
So, the blueprint of the drafting table is a pdf of an actual blueprint (scanned for some other reason). The computer has a screen grab decaled on its "glass."
The walls are a (middling easy) extrusion from the 2D plan set.
Revit makes much of this easier. Mind, it's meant to work in 3D from the get-go. So, you have to plan a bit further ahead. Even so, it likes to frustrate me at least once a day. $5000 per seat software, and nobody thought to include a way to model a fence. Phased construction with tower cranes, sure. But, a wooden stockade fence? Not so much. Sigh.