Retinal optic flow during natural locomotion
Fig 10
Comparison of representative flow field during stabilization versus during a saccade (195 deg/s up and to the left).
The top row shows retinal motion while the eye is fixating and the second row shows motion during a saccade. The bottom row shows the difference for velocity, curl, and divergence plots between the motion during a fixation and motion during a saccade (that is, between the top and middle rows. The flow fields on the left show that when gaze is stable, motion is outwards, away from fixated location. During the saccade, flow is strongly influenced by the direction of the saccade (motion in the opposite direction is added). On the right side of the Figure, velocities are low with 0 deg/s at the fovea when gaze is stabilized. By contrast the saccade results in speed at the fovea equal to the speed of saccade (195 deg/s), with velocities at all other retinal locations increased by more than an order of magnitude. The saccade also results in increase in curl values by more than order of magnitude and alters the spatial structure of curl pattern. Similar to effect on curl values, divergence values change by order of magnitude, and spatial structure is altered. Note that the scale of the difference plot in the bottom row differs by a factor of over 10 in Fig 9.