Optical information for detecting loss in one's own forward speed

Optical and Event-Duration Variables Affecting Self-Motion Perception.

“…The descent and 1'!vel events were matched in adjacent trials in order to best ref lect biasfree sensitivity at the time during the test session when the descent-trial data were collected. Previous studies (e.g., Owen, Warren, Jensen, Mangold, & Hettinger, 1981) have shown that sensitivity improves with practice; thus it was decided to present the two matching events contiguously.…”

“…An earlier experiment had indicated that observers are primarily sensitive to fractional loss in altitude when detecting descent (Owen, Warren, Jensen, Mangold, & Hettinger, 1981 Denton, 1973Denton, , 1974 preview periods, the concern was for the possibility that preview periods of different durations would differentially favor or interfere with sensitivity given particular optical conditions, e.g., different flow rates. The results indicate that this is a complex issue.…”

“…rn, Jensen, Mangold, and Hettinger (1981) demonstrated the ,i h i1)e for self-motion perception is sensitive to fractional ratc_ 4.t itude, rather than absolute rates of change. One advantage ot v'Ir,,y is that when approaching a surface, the inverse of fractional…”

A Metric to Quantify Virtual Scene Movement for the Study of Cybersickness: Definition, Implementation, and Verification

“…The flow patterns were represented by a function consisting of the relative velocities between the objects of interest and the aircraft. The effects of these flow patterns and other optical variables on the perception of self-motion have subsequently been studied extensively (e.g., Owen and Freeman, 1986;Owen, Warren, Jensen, Mangold and Hettinger, 1981;Owen, Wolpert and Warren, 1984;Owen, Hettinger, Pallos and Fogt, 1985;Owen and Warren, 1987). The variables investigated include the optical flow rate (flight velocity divided by instantaneous altitude); optical acceleration (product of flight velocity and descent rate divided by the square of the difference between the initial altitude and altitude to be descended to); optical density (instantaneous altitude divided by ground texture size); and optical splay (rate of descent divided by altitude).…”

Perceptual dimensions of visual scenes relevant for simulating low-altitude flight.

“…Changes in speed and altitude are detected with relatively impoverished simulator scenes consisting of simple grid patterns on flat terrain surfaces Owen, Warren, Jensen, Mangold & Hettinger, 1981).…”