The role of visual occlusion in altitude maintenance during simulated flight.

Abstract

The use of visual occlusion as a cue to altitude maintenance in low-altitude flight (LAF) was investigated. The extent to which the ground surface is occluded by 3-D objects varies with altitude and depends on the height, radius, and density of the objects. Participants attempted to maintain a constant altitude during simulated flight over an undulating terrain with trees of various heights, radii, and densities. As would be predicted if participants used occlusion, root-mean-square error was related to the product of tree height and tree density (Experiment 1) and to the product of tree radius and tree density (Experiment 2). This relationship was also found for simulated terrains with a more realistic mixture of tree heights (Experiment 4). The authors present a modification to an occlusion model (T. Leung & J. Malik, 1997) that can be used to approximate occlusion in the context of LAF, and they evaluate the modified model using the present LAF data. On a practical level, simulating 3-D objects is computationally expensive. The present results suggest that performance may be maintained with fewer objects if their size is increased. Keywords: aviation, perception and action, visual occlusion, simulationThe ability to effectively control movement through the environment is one of the most important perceptual-motor skills humans possess. Whether walking, cycling, driving, or flying we must control our rate and direction of travel in a manner that will allow us to reach our goal while avoiding collisions with obstacles. Safe performance of these actions frequently requires that we regulate our position relative to some object or feature in the environment-for example, maintaining a safe distance behind a lead car in driving or keeping a safe distance from the road edge when cycling. In the present article we consider a particular example of this ability: regulating height above the ground in simulated aircraft flight.Of all of the perceptual-motor tasks performed by military pilots, low-altitude flight (LAF) is one of the most demanding and potentially the most dangerous. LAF can involve maintaining an altitude of less than 40 m while traveling at speeds up to 232 m/s (450 knots). Not surprisingly, this flight task accounts for disproportionately high numbers of accidents relative to the total number of flight hours (Wiener, 1988). Given this high level of risk, flight simulators are now used extensively to provide a training environment for pilots to acquire LAF skills.In order for simulator training of any flight skill to transfer positively to the real world, it is critical that the simulation include the necessary visual cues. Owing to both computational and display limitations, current flight simulators cannot provide all of the cues associated with LAF. The questions then become, to what extent can LAF tasks be performed given the cues that are available, and to what extent can those cues be traded off so as not to exceed limited simulator capabilities? Answering these questions requires empirical research...

Effects of anxiety and cognitive load on instrument scanning behavior in a flight simulation

“…Performance Similar to previous studies studies [10,19,20] root mean square error (RMSE) of the vertical deviation from the ideal 3 • glideslope was used as the performance metric. In X-Plane, one glideslope dot represents a 0.28 • error.…”

Pilots’ gaze strategies and manual control performance using occlusion as a measurement technique during a simulated manual flight task

“…The observed flightpath deviations show similar amplitudes compared to other flight simulator studies (Ebbatson et al 2010;Haslbeck and Hörmann 2016), thus indicating that the occlusion conditions in this study did affect the participants but did not lead to a complete failure in the manual flying task (Table 6). Thus, occlusion appears as an approach to generate valid data to analyze pilots' performance under conditions of restricted visual resources (see Gray et al 2008). …”

“…Occlusion was successfully used to evaluate operator performance and estimate attentional demand not only in the automotive domain, but also in other fields involving highly skilled performance such as aviation (Milgram 1987). Gray et al (2008) have taken the occlusion paradigm in a different way: in a manual fine-motor flying task to maintain a constant altitude, they occluded the ground surface by 3D objects. In the current study, the benefit compared to more intense techniques such as eye tracking is that occlusion allows for a very selective and controlled manipulation of an operator's visual perception, which is a very important channel for many psychomotor control tasks (Helleberg and Wickens 2003;Gelau and Krems 2004) with a clear distinction between the information a subject should receive and the information to be ignored.…”

2D vs. 3D Visual Cues for Altitude Maintenance in Low-Altitude Flight

“…Altitude change detection was good even when there was no texture on the ground surface suggesting that changing object size was a reliable visual cue to altitude maintenance. More recently it has been shown that the presence of 3D objects provides motion parallax (Covas, Patterson, Geri, Akhtar, Pierce, & Dyre, 2005) and visual occlusion (Gray, Geri, Akhtar, & Covas, 2007) cues that can be used to maintain altitude.…”