See my bog post about MAV perception using a single camera.
In assignment I got familiar with the Kinect technology. The most noticeable thing about this technology among its competitors is its cost. Below you can see a video of the project:
The phone, which was taking the video, was used as a block in front of the camera. The code was written to make a part of the screen change colors when an object was at least 1.1meters from the prime sense. The camera was 1.1 meters or closer throughout the video therefore when the camera was moved, the certain part of the screen changed colors.