Investigating the role of binocular depth cues in altitude judgements with real and simulated imagery


  1. Deas, L.M.
  2. Allison, R.S.
  3. Hartle, B.
  4. Irving, E.L.
  5. Wilcox, L.M.
Corporate Authors
Defence Research and Development Canada, Toronto Research Centre , Toronto ON (CAN);York University, Toronto ON (CAN) Centre for Vision Research;University of Waterloo, Waterloo ON (CAN) School of Optometry and Vision Science
Canadian Forces Health Services (CFHS) has an ongoing requirement to evaluate CAF aircrew vision status both at initial recruitment and over the course of their career. Vision status is derived from a set of clinical tests. Stereopsis, while not presently an aircrew requirement, is suspected to be important for certain aircrew tasks. Stereopsis is the ability to perceive depth based on binocular disparity and individual differences in stereoscopic ability (e.g. stereoacuity) are substantial. This feature of functional binocular vision may provide, for example, additional precision in estimating altitude by eye when flying close to the ground (e.g. during rotary wing operations). Accordingly, DRDC is undertaking a project to investigate the link between clinical tests of stereopsis (e.g. those measured by CFHS) and aircrew operational performance. In this series of experiments, we investigate the importance of stereopsis in callto- landing during rotary-wing operations, typically performed by the Flight Engineer. Six types of naturalistic still imagery (three viewing angles, two landing locations) were captured at different altitudes ranging from 10 to 100 ft. The images were displayed stereoscopically and observers were asked to estimate the distance to the ground relative to a reference image. All observers participated in stereoscopic 3-D and 2-D viewing conditions. There was no consistent significant difference between the 3-D and 2-D viewing conditions, and therefore we f
aircrew vision standards;stereopsis;altitude estimation;depth perception
Report Number
DRDC-RDDC-2016-C352 — Contract Report
Date of publication
01 Oct 2016
Number of Pages
Electronic Document(PDF)

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