The Role of Visual Occlusion in Altitude Maintenance During Simulated Flight

Robert Gray, G. A. Geri, S. C. Akhtar, C. M. Covas

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)475-488
Number of pages14
JournalJournal of Experimental Psychology: Human Perception and Performance
Issue number2
StatePublished - Apr 2008


  • aviation
  • perception and action
  • simulation
  • visual occlusion

ASJC Scopus subject areas

  • Experimental and Cognitive Psychology
  • Arts and Humanities (miscellaneous)
  • Behavioral Neuroscience


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