Tracking video projector.

Jon Howell came up system which projects his name his office door. The thing is, his office door slides on tracks so he made a projector that can follow the movement of that screen. He used a laser printer to make a black and white pattern that indexes the movement of the door using a quadrature encoder. When it senses door movement a servo motor rotates the projector to match the change in the door’s location. As you can see in the video after the break it works even if the door is moved quickly.