Fig 1.

Overview of the cases in which an object may cross the future path of a moving observer (right panels) and corresponding optic flow fields (left panels). In panels on the left, red and blue arrowheads correspond to optic flow from the object and background, respectively. In the right panels, the black arrow shows the heading direction of the observer and red arrows show the movement direction of the object. In panel b, the fixed-depth object moves in depth at the same rate as the observer (v). (d) A depiction of self-motion in the presence of an approaching moving object that occupies much of the visual field (45° of the 100° field of view). Even though the FoE due to the observer self-motion relative to the background (blue disk) and to the object (red disk) are separated by 20°, the heading bias is quite small—only 1–3°.