Use of optical edge and optical flow rate: Information in the perception and control of ground velocityPrevious research (Denton, 1980; Larish & Flach, 1990; Owen, Wolpert, & Warren, 1984; Awe & Johnson, 1989) suggests that people will use one or both of two optical variables as information for the perception and/or regulation of ground velocity. The first variable, global optical flow rate (FR), reflects the angular optical speed, and is proportional to the observer's ground velocity scaled in altitude units, i.e. velocity divided by altitude. Therefore, flow rate is a reliable indicator of ground velocity only under the condition of constant altitude. The second variable, optical edge rate (ER), reflects ground velocity as the frequency at which the optically specified ground edges pass across some optical region. Therefore, edge rate is an accurate indicator of ground velocity when altitude varies, but not when texture density varies. Since both flow rate and edge rate can vary independently of forward ground velocity, accurate ground-velocity control may depend upon using the best optical variable.
Document ID
19950063480
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Johnson, Walter W. (NASA Ames Research Center Moffett Field, CA, US, United States)
Awe, Cynthia A. (Western Aerospace Lab. Moffett Field, CA, US, United States)