Interacting with a virtual object by tracking the movement of two points

Disclosed is a method and system for interacting with a virtual object shown on a computer screen. The simultaneous movements of two or more user-controlled points in 3-dimensions, are tracked using a motion monitoring system, such as cameras. The movement of the points is then interpreted as an interaction with the virtual object and results in a corresponding alteration of the display of the object. The interaction may be a compound manipulation (i.e. translation, rotation, scaling and/or skewing) of the object. The tracked points may be the hands to the user, using markers, such as coloured pads or LEDs on the user's fingers. The system may use shape recognition of a set of points to recognise a preset shape having set meaning. The screen may display an image of the user's hands. The object may be a geoscience object showing the underground rock strata.