Peripheral visual field, fixation and direction of heading

Although moving human observers actively fixate points in the world with their eyes, computer vision algorithms designed for the estimation of structure-from-motion or egomotion typically do not make use of this constraint. In this paper, we investigate the computational advantage of fixation. The main contribution of this work is to specify precisely the form of the optical flow field for a fixating observer moving in a rigid world. In particular, we show that the use of a hemispherical (retinal) imaging surface combined with the active process of fixation generates an optical flow field of a particularly simple form. A further contribution is the finding that the sign of retinal flow at the retinal periphery can be used to predict collisions.