Digital Desk (1991)
The DigitalDesk is built around an ordinary physical desk and can be used as such, but it has extra capabilities. A video camera is mounted above the desk, pointing down at the work surface. This camera's output is fed through a system that can detect where the user is pointing (using an LED-tipped pen) and it can recognise the documents that are placed on it. The more advanced version also has a computer-driven projector mounted above the desk enabling electronic objects to be projected onto real paper documents -- removing the burden of having to switch attention between screen and paper and allowing additional user-interaction techniques. [invented and built by Pierre Wellner, Xerox EuroPARC]