The invention provides an apparatus, a system and a method. The apparatus, the system and the method are used for controlling and interacting within an interaction volume (1) within a height over the coordinate plane (12) of a computer such as a computer screen, an interactive whiteboard, a horizontal interaction surface, a video / web-conference system, a document camera, a rear-projection screen, a digital signage surface, a television screen or a gaming device, to provide pointing, hovering, selecting, tapping, gesturing, scaling, drawing, writing and erasing, using one or more interacting objects (2), for example, fingers, the hands, the feet, and other objects, for example, pens, brushes, wipers and even more specialized tools. The apparatus and the method can in a system be used together with, or even be integrated into, data projectors (3) of all types and its fixtures / stands (4), and used together with flat screens (12) (like LCD, plasma, OLED, rear-projection screen, etc.) to render such display systems interactive. The apparatus consists of a single camera (5) covering the interaction volume (1) from either a very short distance or from a larger distance to determine the lateral positions (X,Y) and even capturing the pose of the interacting object(s) (2).