Abstract: A user interface input apparatus and method allows the detection of when and where a user touches a surface of a translucent screen by the processing of imagery generated by a camera that views an opposite surface of the screen. An input device and system includes a translucent screen; an image capture device located for imaging a first side of the screen opposite a second side where user interaction occurs; and an image processor coupled to the output of the image capture device to determine at least one of where and when a person touches an area on the second side of the screen by a change in intensity of light emanating from the touched area relative to a surrounding area.

Abstract: A positioning system for locating at least one interactive projection unit, and methods for operation thereof is disclosed. The positioning system includes equipment for providing multiple degrees of freedom for locating the at least one projection unit. The at least one projection unit is equipped with various components and capabilities to provide for projection onto surfaces within a variety of settings, and thus provide for display, information, interaction and computing in the variety of settings.