[CEATEC 09] KDDI was showing this bizarre “joystick” for mobile phones based on a plastic tube that is stuck on the back of a cellphone by a magnet. The idea is to attach this white tube so that the phone’s camera can look into it. At the end of the joystick, there’s a color pattern (one red and one blue square) that the camera can track by “seeing” any motion of these two squares, and voila, you have a camera-based joystick. Great!? Well, not really. The idea is nice, but in practice, the vision-based motion detection method doesn’t work so well for extreme motions because at some point, the camera can’t see what’s at the end of the joystick if it’s bent too much.