The present application is directed to a medical system, comprising a plurality of elongate instruments, each elongate instrument comprising an elongate instrument body having an optical sensor coupled thereto, and a controller configured to determine one or more position and/or orientation variables of each elongate instrument based on signals received from the optical sensor, and register the respective position and/or orientation variables of the elongate instruments in a single reference coordinate system. Further, the present application is directed to a method for registration of a plurality of elongate instruments, the method comprising the following steps: providing a plurality of elongate instruments, each elongate instrument comprising an elongate instrument body； coupling an optical sensor to each elongate instrument body； determining, using a processor, one or more position and/or orientation variables of each elongate instrument based on signals received from the optical sensor； and registering, using the processor, the respective position and/or orientation variables of the elongate instruments in a single reference coordinate system.
