A method for determining a location of an object in a three-dimensional localization field created by a localization system includes the following steps: providing a catheter having known spacing between electrodes； providing a lookup table of data correlating locations of an object within the localization field with measurements made by the localization system； placing the catheter into the localization field； using the localization system to determine the location of the electrodes based on the lookup table； calculating an observed distance between electrodes； comparing the observed distance to the known electrode spacing； and adjusting the lookup table to more accurately measure the spacing of the electrodes. A Kernel function, such as the derivative of a Gaussian function, may be used to update the lookup table.
