Methods and systems method for sensing a position of an object in a body include positioning a probe in the body, making measurements of mapping electrical currents passing between at least a first electrode on the probe and a plurality of second electrodes on a surface of the body, calibrating the measurements so as to compensate for one or more non-ideal features of the measurements including effects of system-dependent electrical coupling to one or more devices other than the first electrode and the second electrodes, and computing the position of the probe in the body using the calibrated measurements.
