[CEATEC 2010] Hitachi was demonstrating a user-interface that was based on a retro-projector and a pair of cameras (infra-red and regular color). The retro-projector allows the image to be posted on a large surface while keeping the cost of the actual display down, as there is no gigantic touch-sensor required. If this is to be used in a public place, it might also be more convenient if people don’t put their fingers all over. The cameras can detect slight hand motion like getting closer or farther from the surface, and of course left/right/up/down. Overall, the user interface is interesting but the optical sensor is of course not as precise as an actual touch surface. We would need to know what the cost is. To truly know what the benefits of this concept is because the trade-offs are serious.