Abstract
Purpose :
Augmented reality (AR) has been explored as a tool for lower-cost training in medical, industrial assembly, design, and education. Presentation of AR content requires a balance of its transparency without compromising the visibility of the surrounding physical objects. As a result, AR headsets can cause vergence-accommodation conflict and eye fatigue. It has been found that lower contrast drives weaker vergence and poorer depth perception. However, little is known about the effect of AR transparency on oculomotor eye alignment. Here, we determined the contrast thresholds for horizontal and vertical disparity-driven eye alignments for various levels of transparency.
Methods :
Subjects(n=4) performed the task while wearing a pair of Epson Moverio BT300 AR smart glasses. The AR stimuli consist of a one-octave bandwidth filtered noise pattern of 2cpd with a disparity of 5 arcmin overlay on a background with zero disparity. We measured the contrast thresholds for producing a detectable nonius shift for 3 transparency levels (low, middle, and high) and 2 background conditions (grey and a black-and-white natural scene photograph) for horizontal and vertical disparity. Responses from the five staircase runs were combined into a single psychometric function, then fitted with a Weibull that converges to 82% correct performance.
Results :
The contrast sensitivity was robust at middle and high transparency. Despite higher opacity at high transparency, there was no significant improvement of sensitivity when compared to the middle level. However, at low transparency, the contrast sensitivity reduced significantly. A cluttered background reduced the sensitivity at all transparency levels by two- to four-fold. There was no significant difference between horizontal vs. vertical results.
Conclusions :
Even with a fusible background, the AR overlay with relatively low contrast is enough to drive the eye alignments. Mid transparency with the AR target and its surround in the middle visibility level is sufficient to drive contrast sensitivity of disparity-driven eye alignments. Lower transparency and cluttered background show a weaker drive to vergence, for both horizontal and vertical eye alignments, and may cause strain to the oculomotor systems. Careful manipulation of transparency and its contrasts should be taken into consideration when designing AR visual content.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.