Thanks, guys! Job’s done, there’s time to chat now.
My basic problem here was that I used high-poly furniture (Easy to download and good-looking). If there were med-res versions of it, it would have been better. Optimal would have been low-res NURBS-versions of it, but I had no time to start modelling a little library of these.
Make2D I tried, took forever because of the high polycount, had to cancel.
Tried Ngonulate, does not work too well in this case:
Quadrangulate does not help much, because even if the mesh diagonal edges are gone, there still would be way too many edges. If you zoom out, such a chair would look just black in shaded mode.
That’s why a mode supporting outlines is the way to go. I found (too late) the ‘Technical’ mode to do just that:
Altough the smaller artifacts are not so nice, it would be usable for the look I was after. Problem with it (besides that I discovered it too late) is that it is unusably slow! Much slower than the VisualArq ‘Hidden’ mode I used in the end (with retouching, unfortunately).
Edit: letting the ‘technical’ mode run on the scene (a 50 x 15m building floor fully furnitured) - still working, after minutes. No go.
So, it wasn’t as easy as I hoped.