Magnetic field based location determination

One or more non-transitory computer-readable storage media including instructions stored thereon that, in response to being executed by one or more processors, cause a system to perform operations, the operations comprising:

• obtaining a magnetic field vector that corresponds to a location within a building, the magnetic field vector being based on an output reading of a magnetometer of an electronic device;
• obtaining orientation information that corresponds to a device orientation of the electronic device at a time that the output reading of the magnetometer is obtained, the orientation information being based on an output reading of one or more inertial sensors and indicating the device orientation with respect to a map-coordinate system of a magnetic field map;
• and
• rotating the magnetic field vector based on the orientation information to generate a normalized magnetic field vector that is normalized with respect to the map-coordinate system, the normalized magnetic field vector and the magnetic field map being used to determine a location of the electronic device.

An electronic device comprising:

• a magnetometer configured to generate a magnetic output reading that indicates a magnitude and a direction of a magnetic field;
• an inertial sensor configured to generate an inertial output reading that indicates an orientation of the electronic device;
• one or more non-transitory computer-readable storage media including instructions stored thereon;
• and
• one or more processors configured to receive the magnetic output reading and the inertial output reading and configured to, based on the instructions stored on the one or more computer-readable storage media:
• obtain, based on the magnetic output reading, magnetic field information that corresponds to a location;
• obtain, based on the inertial output reading, orientation information that corresponds to a device orientation of the electronic device at a time that the magnetic output reading, the orientation information indicating the device orientation with respect to a map-coordinate system of a magnetic field map;
• adjust the magnetic field information based on the orientation information to generate normalized magnetic field information that is normalized with respect to the map-coordinate system;
• and
• determine, based on the normalized magnetic field information and the magnetic field map, that the electronic device is at the location at the time that the magnetic output reading is obtained.