[JonathanFly]

> What is a technique/library that can take an image of a 3d environment/drawing of a room and detect a rough mesh highlighting ground, walls, barriers ?

Well just in case it wasn't obvious, Toon3D, the project being discussed, is doing that. Part of the workflow is asking the user to indicate correspondences between geometry in different images, and each image is processed individually to create blocks of geometry you can toggle on or off visually.

Older projects:

https://github.com/sniklaus/3d-ken-burns

https://github.com/vt-vl-lab/3d-photo-inpainting

I believe there are some NeRF variants that do something like this from a single image as well, but I haven't personally tried any.