For the test project we chose to use the lines to visualize energy. In the first attempt rigatoni posed in a way that looked like he was pushing a large object. The lines illustrate force and motion. In the second attempt I added lines in front of a fan to illustrate the movement of the air.

In the full implementation the app would be able to detect moving objects in the static scene and draw in lines where there's a drastic movement. It would have to distinguish between camera movement and object movement because otherwise it would think that the room moving relative to the camera was a moving object in the room.