An electromagnetic tracking method includes generating an electromagnetic field (14) in a region of interest (16). The electromagnetic field is subject to distortion in response to a presence of metal artifacts proximate the electromagnetic field. An array of reference sensors (30,50,102,104,110) having a predefined known configuration are disposed proximate the region of interest. A first set of locations of the array of reference sensors is determined with respect to the electromagnetic field generator (12) in response to an excitation of one or more of the reference sensors via the electromagnetic field. A second mechanism (28), other than the electromagnetic field, determines a first portion of a second set of locations of at least one or more sensors of the array of reference sensors with respect to the second mechanism, the second mechanism being in a known spatial relationship with the electromagnetic field generator. A remainder portion of the second set of locations of the reference sensors of the array of reference sensors is determined in response to (i) the first portion of the second set of locations determined using the second mechanism and (ii) the predefined known configuration of the array of reference sensors. The method further includes compensating for metal distortion of the electromagnetic field in the region of interest as a function of the first and second sets of reference sensor locations of the array of reference sensors.