1. A method of operating an autonomous vehicle, the method comprising: receiving a measurement of landmark position for each of a plurality of landmarks from at least one image sensor; estimating a kinematic state of the autonomous vehicle in a global frame based, at least in part, on the received measurements from the at least one image sensor; estimating a position of the plurality of landmarks in a frame of the autonomous vehicle and in the global frame based on the received measurements from the at least one image sensor; forming a plurality of unit projection vectors between the estimated positions of the plurality of landmarks in the global frame; forming a plurality of unit projection vectors between the estimated positions of the plurality of landmarks in the frame of the autonomous vehicle; and calculating heading angle drift errors based on the plurality of unit projection vectors in the global frame and the plurality of unit projection vectors in the frame of the autonomous vehicle; and updating the estimate of the kinematic state of the autonomous vehicle in the global frame based on the calculated heading angle drift errors.