Disclosed herein is a method for navigating an imaging instrument in a branched structure. The branched structure includes a plurality of landmarks. The method includes selecting a target in the branched structure, selecting a first landmark from the plurality of landmarks, acquiring a virtual model of the branched structure, extracting a first virtual image of the first landmark from the virtual model, acquiring a first live image of the first landmark by the imaging instrument, and registering the first live image with the first virtual image. The first landmark is associated with the target.
