A method and system for maintaining calibration of a distributed localization system are presented. After a baseline calibration of sensors distributed on a working instrument and reference instrument, if movement of the reference instrument is detected, shape sensing data from a Bragg shape sensing fiber also coupled to the reference instrument may be utilized to recalibrate the localization system. The reference instrument preferably is located intraoperatively in a relatively constrained anatomical environment, such as in the coronary sinus of the heart, to prevent significant movement.