Given an arbitrary 3D model of a house, I want to write an algorithm to get one specific room. I need that single room as a manifold shape (the watertight air volume to calculate acoustics).

Unfortunately I find no research, algorithms or implementations. Do you know any existing stuff that can be used? Even the right wording for describing my problem would help me. I am searching for a hull but I am only finding research regarding outer hulls around point clouds. I am searching for the inner triangle hull in an arbitrary triangle soup.

Thoughts for implementing such an algorithm:

• The user loads an existing 3D model (triangle soup). If I can detect a single watertight/manifold object, I use this as the room.
• If it is not that ‘easy’ I plan to let the user select an arbitrary point somewhere in the model. Starting from there I try to find the surrounding walls.
• I guess I will try to walk connecting structures starting from the closest point of the triangle soup and try to find the closed shape. There are of course difficulties to detect openings and do something sane at intersections.

Do you know any existing algorithms that I have overlooked?
Any better sites for discussing these kinds of problems?