Figure 1.

Schematic illustration of the consequences of rotational (upper diagram) or translational self-motion (bottom diagram) for the resulting optic flow. Superimposed images were either generated by rotating a camera around its vertical axis or by translating it forward. Rotational self-motion leads to image movements (red arrows) of the same velocity (reflected in the arrow length) irrespective of the distance of environmental objects from the observer. In contrast, the optic flow elicited by translational self-motion (blue arrows) depends on the distance between objects from the observer. Hence, translational optic flow contains spatial information.