need a laser light emitter and receiver (web cam, cell phone grade)
Device emits light pattern and directs adjustment by viewing what it sees vs what it should see.
Draw horizontal pattern of dots, or present any number of possible geometric patterns on wall to allow camera to determine orientation to surface.
Any geometric distortion of the image you intend to portray on the surface would result in something you can read to adjust your position.
(this is Mind, actually, project measure interpret, modify, experience, interact/project, monitor...not necessarily in that order.)
Draw
This would be an excellent tool for painters to determine physical scale.
If you could fill a room with lasers that do this, would it be interesting to see?