Flow segmentation during locomotion

Figure 2. (Left) Heat map of speeds across central 90 deg. Looking in the distance leads to large speed gradient across the retina. (Right) Optic flow patterns divergence vary during a step. THe rotational flow changes direction as the body sways left and right. RHS show divergence. Navigating around obstacles is an essential part of natural locomotion. Obstacle avoidance can be further complicated when the obstacles are in motion. However, locomotion itself introduces a complex time-varying pattern of visual motion on the retina (1) that depends on the location of gaze in the scene. Thus, being able to discern what motion in the visual field is caused by self-generated versus external motion is important. In an exploratory study, we measured retinal flow patterns of pedestrians walking across an intersection in order to get a better quantitative understanding of the motion signal walkers must parse. We tracked binocular eye movements using a Pupil Labs Invisible tracker, and then transformed the images from the head camera to retinal coordinates. While walking, subjects’ gaze patterns consist of fixations that are largely stable in the scene, separated by saccades. We used the Deepflow optic flow estimation