
With increased use of stereoscopic devices, it is important to emulate real-world practices and study physiological and perceptual effects over long viewing periods. Stereoscopic channels may not always be perfectly aligned, and alignment may shift with use. In this experiment, we investigated the impact of vertical misalignment between left and right-eye imagery during stereoscopic remote vision system (sRVS) use. For three-hour periods, participants performed a simulated aerial refueling task. Their goal was to fly the boom into a receiver aircraft receptacle as quickly as possible without scratching the aircraft. After each successful connection, the participant monitored several systems, which required changes to version and vergence position. Binocular eye position was recorded throughout the task. While performance increased over time, the survey results showed that participants were experiencing strain over time and with increased misalignment. However, only one oculomotor change – horizontal vergence – was observed over time. Time series analysis revealed a more complex relationship between pupil size and time within each block. To further investigate the relationship between eye movement behavior and vertical misalignment, a principal component analysis was performed. These results identified eye movement behaviors that are sensitive to changes in stereoscopic misalignment and have the potential to be used to indicate oncoming fatigue. This experiment highlights the importance of considering the visual system as a whole when assessing stress and not simply relying on performance metrics.

Vergence-accommodation (VA) mismatch is a component of stereoscopic 3D remote vision system (RVS) design linked to depth misperception and visual discomfort. VA mismatch is caused by an unnatural conflict between the focal distance of the image (and thus accommodative demand) and the binocular vergence demand. A possible solution to mitigate VA mismatch is to change the accommodative demand with an optical correction, reducing the mismatch with the vergence demand. This experiment investigated the effect of low-add spectacle lenses (eyewear) on RVS performance and visual comfort. While previous research showed a positive effect of decreasing VA mismatch with the use of switchable lenses to adjust focal distance, the optical changes in this investigation were insufficient to make a difference. We conclude that the use of eyewear with a small dioptric add is not an effective solution to improve stereoscopic RVS performance or viewing comfort.

Three-dimensional (3D) displays become more and more popular in many fields. However, visual fatigue is one of the critical factors that impede the wide range of applications of 3D technology. Although many studies have investigated the 3D visual fatigue, a few of them are based on continuous viewing 3D contents. In this paper, we propose a method to evaluate visual fatigue through subjective scoring and objective measuring the physiological parameters during the continuous viewing 3D/2D movie. In the viewing, we test the objective and subjective indicators, including the heart rate (HR), blink frequency (BF) and percentage of eyelid closure over the pupil over time (PERCLOS) and the subjective scoring (SS). Before and after viewing the video, VRT, PMA and questionnaires are measured. Experimental results showed that the subjective score and objective indicates of visual fatigue increased gradually with viewing time although it was fluctuated. The symptoms of visual fatigue were generally more serious after viewing 3D movie than 2D ones. Based on the results above, a model was built to predict visual fatigue from HR and BF during continuous viewing 3D video processes.