An apparatus, comprising: a probe adapted for insertion into a chamber of a heart of a living subject and having a plurality of intracardiac electrodes that can be disposed at respective locations in the heart; a torso vest having a plurality of sensing electrodes, magnetic location sensors, active current location sensors and patches for establishing galvanic contact with the skin; a wireless body marker attachable to the subject; wireless tracking circuitry configured to determine a location of the wireless body marker with respect to the torso vest, by determining a first location of the wireless body marker with respect to an external fiducial marker; determining a second location of a magnetic location sensor of the torso vest with respect to the wireless body marker; and computing a location of a sensing electrode of the torso vest with respect to the wireless body marker from the second location; a first processor operative for determining the respective locations using the active current location sensors; a signal generator delivering electrical calibration signals to the intracardiac electrodes for emission; and a second processor receiving the calibration signals in the sensing electrodes of the torso vest and operative for determining relationships between the emitted calibration signals and the received calibration signals in the intracardiac electrodes to map a correspondence between the received calibration signals and the respective locations. a probe adapted for insertion into a chamber of a heart of a living subject and having a plurality of intracardiac electrodes that can be disposed at respective locations in the heart; a torso vest having a plurality of sensing electrodes, magnetic location sensors, active current location sensors and patches for establishing galvanic contact with the skin; a wireless body marker attachable to the subject; wireless tracking circuitry configured to determine a location of the wireless body marker with respect to the torso vest, by determining a first location of the wireless body marker with respect to an external fiducial marker; determining a second location of a magnetic location sensor of the torso vest with respect to the wireless body marker; and computing a location of a sensing electrode of the torso vest with respect to the wireless body marker from the second location; determining a first location of the wireless body marker with respect to an external fiducial marker; determining a second location of a magnetic location sensor of the torso vest with respect to the wireless body marker; and computing a location of a sensing electrode of the torso vest with respect to the wireless body marker from the second location; a first processor operative for determining the respective locations using the active current location sensors; a signal generator delivering electrical calibration signals to the intracardiac electrodes for emission; and a second processor receiving the calibration signals in the sensing electrodes of the torso vest and operative for determining relationships between the emitted calibration signals and the received calibration signals in the intracardiac electrodes to map a correspondence between the received calibration signals and the respective locations. <EOS>