1. A method of determining whether to add a landmark to a map for navigation, the method comprising: retrieving an image from a visual sensor; comparing features from the image to a plurality of stored features; generating a list of matching landmarks from the comparison; filtering matching landmarks from the list based at least in part on reliability tests; and proceeding to a landmark creation process when there are no remaining matching landmarks in the list; wherein retrieving, comparing, generating, filtering, and proceeding are performed under the control of electronic hardware.