1. A method for computing a current gaze location of a subject in a joint error minimization, the method comprising: capturing at a plurality of glints in a left eye of the subject and a plurality of glints in a right eye of the subject using at least four light sources; based on the plurality of glints captured in the left eye and a pupil center of the left eye, computing a left homography matrix; based on the plurality of glints captured in the right eye and a pupil center of the right eye, computing a right homography matrix; and combining the left homography matrix with the right homography matrix to determine the current gaze location.