The perception of an opening from expanding motion

Abstract

The ability of humans to detect an opening's 3-D structure from expanding motion was tested, Computer simulations of dotted tunnels were used to generate optical flows typically encountered when one moves through an opening, Experiment 1 qualitatively tested the ability to detect the shape of a tunnel's vertical section, The observers could choose the correct shape for each of seven simulated shapes, The percentages of correct responses were much higher than those under static conditions, Experiment 2 tested whether or not one could quantitatively detect the vertical-horizontal proportion of the elliptic tunnels. The result shows quite high correlations (r = ,93~.97) between perceived proportions and simulated ones. The slopes of the regression lines were around 1.0. Experiment 3 investigated the necessary stimulus duration for detecting an opening's shape. Relative size (width and height) was significantly detected under four-frame (72.7-msec) conditions by 3 out of 4 subjects. The other subject performed well under eight-frame conditions. These results indicate that the human visual system can instantly detect the 3-D structure of an opening surrounded by objects from expanding optical flows while one is in forward motion.

Depth Perception through Circular Movements of Dots

“…With the tunnel configuration, it was possible to create an endless expansion display representing a rigid 3-D object. One can easily perceive a 3-D tunnel from the expansion display on the screen (Ito 1996). The speed distribution on the screen is shown in figure 1.…”