a system for determining the spatial position and orientation of each of a plurality of bodies . each one of the bodies has at least three markers in a predetermined , relative geometric relationship . the markers are adapted to emit energy in response to an activation signal and / or to reflect energy impinging upon such passive marker from an activatable energy source . a common energy detector is provided for detecting the energy emitted by the active marker and the energy reflected by the passive marker . a common processor is provided . the processor has a memory . the memory has stored therein the predetermined , relative geometric relation of the markers for each one of the bodies . the processor compares the stored predetermined geometric relation of the markers for each of the bodies with the energy detected by the energy detector to identify the bodies emitting / or reflecting the detected energy . with such an arrangement , a body can be tracked using a very simple sequence of operation in real - time with robust positive marker identification by taking advantage of a simple marker placement methodology . multiple bodies can scan thereby be tracked simultaneously .