1. A method of localizing a mobile device via a multiple-particle autonomous localization and mapping system, the method comprising: performing autonomous localization and mapping with a plurality of particles, where a particle includes a device pose estimate and a map, where the map includes one or more landmarks; receiving an indication that a landmark has been recognized and a visually-measured relative pose to the landmark has been estimated, where the landmark has been recognized using visual features from a visual sensor coupled to the mobile device, where the relative pose corresponds to a visually-measured difference in pose between a landmark pose and a pose corresponding to the visual observation; and updating at least one of the plurality of particles at least partly in response to receiving the indication of the recognized landmark, wherein updating further comprises: using a prior pose estimate and dead reckoning sensor data to compute a new pose estimate for particles in a selected group based on the estimated change in pose; and using the landmark pose and the visually-measured relative pose estimate to compute the new pose estimate for particles not in the selected group.