I've decided to try to use these trees in a scene with real-world scale... And for that I picked a lovely village where I live :)
It's not the most epic scene in the world, but I like it :) There are still some areas that need polishing. And I'm not sure about the camera angle... I want to show as much as possible (especially that river and also the big mountain in the distance), but it might be more interesting to lower the camera... not to mention that 2d trees are not working so well then the camera is above them...
I got real height map. Unfortunately not the best resolution, but good enough I guess.
and I places the houses exactly where they are supposed to be, based on a regular map...