INTERACTIVE DIGITAL ARROW (D'ARROW) THREE-DIMENSIONAL(3D)POINTING DEVICE

An interactive three-dimensional (3D) pointing device for selecting points within a subject employs a tracking device which determines the position of the operator, a semi-transparent screen positioned by the operator and the subject and provides this information to a model workstation. The model workstation superimposes computer graphic images of internal structures of the subject on a the semi-transparent screen through which the operator is viewing the subject. The superimposed image is derived from image data either previously generated and stored or obtained with an imaging system. The images of the internal structures are registered with the operator's view of the external structures of the operator. The operator interactively views internal and external structures and the relation between them simultaneously, while moving the screen to select 3D target points at an image depth within the subject. Optionally other input devices may be used to identify current `target points` as selected points. The 3D points are then provided to an output device which utilizes them. Another embodiment employs stereoscopic viewing methods to provide 3D representations of the internal images superimposed on external structures to allow the operator to employ parallax to select 3D points.