Abstract: User interface apparatus for a computer system, comprises: a touch surface having an internal face and a touch face; cameras placed about said touch face and arranged to image the touch face including the surface itself and a volume extending outwardly from the surface on the touch face; and an illumination unit that illuminates the touch side. The illumination unit illuminates separately a) a relatively thin first volume close to the touch surface for touch control—the touch volume, and b) a relatively deep second volume extending away from the first volume for three-dimensional hand or body gesture control— the depth volume, the separate illuminating providing for separate imaging by the cameras of the touch and depth volumes.