Distance Estimation with Night Vision Goggles: A Little Feedback Goes a Long Way

Abstract

Immediate feedback was given to correct observers' estimates of distance in an experiment in which those estimates were made outdoors at night while observers wore night vision goggles (NVGs). Initially observers made unguided estimates of distances between marked positions in an open field. Those distances ranged from 7.6 m (25 ft) to 64 m (210 ft). Later the same observers made more estimates. After each of these they were told the measured distance between the positions. During this training, the observers' height from the ground plane was either at a standing position or at an elevated position raised 2.3 m (7 ft 7 in) from standing position. After the training--either immediately after, a week later, or at both times--observers made unguided estimates of distance for a second time. These latter estimates of ground distance made with the NVGs were improved. Average improvement of the observers' estimates persisted for at least one week after training. This training can be applied to improve clearance estimates and estimates of hover height for pilots of rotary-wing aircraft.

Spatial navigation using night vision goggles

“…37,38 Studies investigating the impact of NVGs and HMDs have found similar performance decrements in various spatial tasks. 5,38,39 The performance findings of the present investigation extend previous research demonstrating that the altered visual effects produced by NVGs contribute to visual deficits and navigation performance. Indeed, participants who wore NVGs during the learning phase had more difficulty recognizing objects (verbal reports would testify to this) and navigating (e.g., trying to avoid running into walls).…”

“…16,53,54 Under degraded visual conditions, when viewing the environment through viewing devices such as NVGs and HMDs, the informational content of the visual scene is reduced and was shown to affect the ability to encode and recognize the visual scene. 5,35 For example, a narrow FOV can reduce the number of landmarks available in the visual field demanding an increased need for head scanning. 2,,35,36 Furthermore, increased head scanning and reduced landmark recognition may increase spatial disorientation.…”

“…a 'grainy' appearance similar to static noise on a television) within the visual display and may influence depth (i.e., reduction in monocular and binocular cues), motion, size and distance perception. 3,4,5,6,7 These limitations may result in increased spatial disorientation, decreased navigation performance and may have the potential to increase workload 8,9,10 which can contribute to a higher potential for accidents and mishaps.…”

<title>Helicopter pilot estimation of self-altitude in a degraded visual environment</title>

“…This is not surprising, as aviators are trained to visually recognize only a few specific altitudes (e.g., a 3-foot hover). Previous research suggests that this ability is readily learned (Crowley et al, 1996;Gibson and Bergmann, 1954;Niall, Reising, and Martin, 1999;Reising and Martin, 1995), but our subjects received no instruction in altitude estimation. This probably accounts for the lack of significant findings when subjects were asked to give a numerical estimate of self-altitude.…”

Out of Sight, Out of Mind? The Effect of Visual Field of View Restrictions on Working Memory

“…Operating under conditions that restrict FoV, such as when using NVGs or HMDs, may impair a pilot's ability to judge distances. Indeed, research has confirmed that restricting FoV causes significant underestimation of perceived distances (Loomis & Knaap, 2003;Niall, Reising, & Martin, 1999;Thompson et al, 2004;Whitmer & Kline, 1998). However, findings from distance perception research are inconsistent with respect to the effect of FoV reductions.…”