Estimates of simulated ground relief as an operational test of stereoacuity for aviators. Sudhama, A., Hartle, B., Allison, R. S., Irving, E. L., & Wilcox, L. M. Technical Report DRDC-RDDC-2019-C119, Defence Research and Development Canada, 2019.
abstract   bibtex   
Stereopsis is not currently a visual requirement for aircrew in the Royal Canadian Air force; however, it has been shown to be relevant to some aviation manoeuvers, particularly aerial refueling and landing. Commercial tests of stereoacuity are widely used to assess stereopsis in clinical practice but may not predict performance in real-world scenarios and tasks. In this series of experiments, we have made the first steps towards development of a stereoscopic depth discrimination task using naturalistic stimuli and a task (terrain relief judgement) that is relevant to flight crew. Stimuli consist of a stereoscopically rendered grassy terrain with a central mound or a dip with varying height/depth. We measured thresholds for discrimination of the direction of the depth offset. For comparison and validation of our Terrain test we also measured observers' performance on a set of commercial (Randot, StereoFly) and purpose-designed stereoacuity tests: the Ledge test, the Bar test, and the United States Air Force School of Aerospace Medicine (USAFSAM) Operational-based Vision Assessment (OBVA) Ring stereo test as additional comparison tests. To assess the impact of uninformative 2D shading cues on depth judgements in our Terrain test, we manipulated the intensity of the shading (low and high). Our results show that the Terrain test can be used as a test for stereovision, and thresholds are measureable for most observers in the low shading condition. However, as shading is intensified, a large proportion of observers (30%) exhibit a strong convexity bias, resulting in reversals in perceived depth. Although the test is a promising measure of stereo, the bias tends to erode the usefulness in this regard. Currently, our analyses show weak correlation between thresholds obtained using our Terrain test and the other stereoacuity tests. However, this is possibly due to the narrow range of, primarily low, thresholds in this set of observers and additional testing with individuals with a broader range of stereoscopic ability is required.
@techreport{Sudhama:2019aa,
	abstract = {Stereopsis is not currently a visual requirement for aircrew in the Royal Canadian Air force; however, it has been shown to be relevant to some aviation manoeuvers, particularly aerial refueling and landing. Commercial tests of stereoacuity are widely used to assess stereopsis in clinical practice but may not predict performance in real-world scenarios and tasks. In this series of experiments, we have made the first steps towards development of a stereoscopic depth discrimination task using naturalistic stimuli and a task (terrain relief judgement) that is relevant to flight crew. Stimuli consist of a stereoscopically rendered grassy terrain with a central mound or a dip with varying height/depth. We measured thresholds for discrimination of the direction of the depth offset. For comparison and validation of our Terrain test we also measured observers' performance on a set of commercial (Randot, StereoFly) and purpose-designed stereoacuity tests: the Ledge test, the Bar test, and the United States Air Force School of Aerospace Medicine (USAFSAM) Operational-based Vision Assessment (OBVA) Ring stereo test as additional comparison tests. To assess the impact of uninformative 2D shading cues on depth judgements in our Terrain test, we manipulated the intensity of the shading (low and high). Our results show that the Terrain test can be used as a test for stereovision, and thresholds are measureable for most observers in the low shading condition. However, as shading is intensified, a large proportion of observers (30\%) exhibit a strong convexity bias, resulting in reversals in perceived depth. Although the test is a promising measure of stereo, the bias tends to erode the usefulness in this regard. Currently, our analyses show weak correlation between thresholds obtained using our Terrain test and the other stereoacuity tests. However, this is possibly due to the narrow range of, primarily low, thresholds in this set of observers and additional testing with individuals with a broader range of stereoscopic ability is required. },
	author = {Sudhama, Aishwarya and Hartle, Brittney and Allison, Robert S. and Irving, Elizabeth L. and Wilcox, Laurie M.},
	date-added = {2018-12-24 13:50:07 -0500},
	date-modified = {2019-09-27 11:02:02 -0400},
	institution = {Defence Research and Development Canada},
	keywords = {Stereopsis},
	number = {DRDC-RDDC-2019-C119},
	title = {Estimates of simulated ground relief as an operational test of stereoacuity for aviators},
	year = {2019}}

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