Examples of arrays of magnetometers that can be used as or as part of an inertial measurement unit (IMU) are disclosed herein. Various methods for using such arrays in order to obtain highly precise and locationally unique data, which can be used to correct for drift effects, are also disclosed. In certain embodiments, the Jacobian matrix of the magnetic field is computed from the magnetometer measurements. This Jacobian matrix data can be used to generate a magnetic field map for a particular environment and/or to locate position, velocity, and acceleration of the IMU by referencing such a magnetic field map.