Patent ID: 8781739

Claim:
A method for revising location estimates, the method comprising: obtaining, by one or more computing devices, a plurality of readings of a magnetic field collected by a magnetometer of a device, wherein the plurality of readings are respectively associated with a plurality of location estimates of the device; obtaining, by the one or more computing devices, a plurality of residual readings by respectively removing a plurality of Earth magnetic field contributions from the plurality of readings, wherein the plurality of Earth magnetic field contributions are respectively based at least in part on the plurality of location estimates and a magnetic field model; identifying, by the one or more computing devices, a plurality of regions of interest based at least in part on the plurality of residual readings; comparing, by the one or more computing devices, each region of interest with at least one other region of interest to identify a plurality of correspondences; and revising, by the one or more computing devices, at least one of the plurality of location estimates based at least in part on the plurality of correspondences.