A Model of Binocular Gaze Estimation

Binocular image-pairs contain information about the three-dimensional structure of the visible scene, which can be recovered by the identification of corresponding points. However, the resulting disparity field also depends on the orientation of the eyes. If it is assumed that the exact eye-positions cannot be obtained from oculomotor feedback, then the gaze parameters must also be recovered from the images, in order to properly interpret the retinal disparity field. Existing models of biological stereopsis have addressed this issue independently of the binocular-correspondence problem. It has been correctly assumed that if the correspondence problem can be solved, then the disparity field can be decomposed into gaze and structure components, as described above. In this work we take a different approach; we emphasize that although the complete point-wise disparity field is sufficient for gaze estimation, it is not in fact necessary. We show that the gaze parameters can be recovered directly from the images, independently of the point-wise correspondences. The relationship between binocular vergence and the resulting epipolar geometry is derived. Our algorithm is then based on the simultaneous representation of all epipolar geometries that are feasible with respect to a fixating oculomotor system. This is done in an essentially two-dimensional space, parameterized by azimuth and viewing-distance. We define a cost function that measures the compatibility of each geometr