A medical system includes an elongate instrument, a tracking system, and one or more processors configured to: receive image data of a set of connected passageways of a patient anatomy; model the set as a plurality of linked bounded-surface elements, each linked bounded-surface element defined in part by basepoints on an anatomical centerline, an element centerline spanning a shortest distance between the basepoints, and a radius; receive position information for a point on the instrument when disposed in the set; based on a comparison of the received position information to the plurality of linked bounded-surface elements, generate adjusted position information for the point; match one of the plurality of linked bounded-surface elements to the point to register the instrument to the image data; create an adjusted instrument image with the adjusted position information; and generate a composite image including the image data of the set and the adjusted instrument image.