• Science of Emotion and Sensibility
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• v.16 no.4
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• pp.509-516
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• 2013

As the visual fatigue induced by 3D visual stimulation has raised some safety concerns in the industry, this study aims to quantify the visual fatigue through the means of measuring the facial temperature changes. Facial temperature was measured for one minute before and after watching a visual stimulus. Whether the visual fatigue has occurred was measured through subjective evaluations and high cognitive tasks. The difference in the changes that occurred after watching a 2D stimulus and a 3D stimulus was computed in order to associate the facial temperature changes and the visual fatigue induced by watching 3D contents. The results showed significant differences in the subjective evaluations and in the high cognitive tasks. Also, the ERP latency increased after watching 3D stimuli. There were significant differences in the maximum value of the temperature at the forehead and at the tip of the nose. A previous study showed that 3D visual fatigue activates the sympathetic nervous system. Activation of the sympathetic nervous system is known to increase the heart rate as well as the blood flow into the face through the carotid arteries system. When watching 2D or 3D stimuli, the sympathetic nervous system activation dictates the blood flow, which then influences the facial temperature. This study is meaningful in that it is one of the first investigations that looks into the possibility to measure 3D visual fatigue with thermal images.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.258-259
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• 2011

3DTV를 시청하는 경우 조절거리는 TV 화면까지의 거리에 해당하지만, 수렴거리는 좌 우 영상의 화면 시차에 따라 영상의 도출과 후퇴의 깊이가 변하게 되고 수렴거리와 조절거리에 불일치가 발생하게 된다. 3DTV의 입체영상을 시청할 때 발생하는 시각적 불편감은 이러한 수렴과 조절과정의 불일치가 가장 주된 원인으로 알려졌다. 본 연구에서는 입체영상의 시각적 자극으로 눈에서부터 시작된 시각피로감이 인체에 전해지는 단계, 즉 정보의 최종 통합기관인 뇌에 전달결과로서의 생체적 반응을 EEG 방법으로 측정하였다. 3DTV 시청 전 후의 뇌파측정과 뇌기능지수 분석에 의한 방법으로 실험한 결과 시각피로는 ${\delta}$, ${\theta}$, ${\alpha}$, SMR, ${\beta}$Low, ${\beta}$High 파 등 여러 종류의 뇌파 밴드에 영향을 미치고 있었다.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.3
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• pp.363-369
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• 2014

Purpose: Three-dimensional (3D) displays are very useful in many fields, but induce physical discomforts in some people. This study is to assess symptom type and severity of asthenopia with their habitual distance corrective spectacle (HDCS) and their binocular vision corrective spectacle lenses (BVCSL) in people who feel physical discomforts. Methods: 35 adult subjects (ages $32.2{\pm}4.4$ yrs) were pre-screened out of 98 individuals to have the highest symptom/asthenopia scores following 65 minutes of 3D television viewing with HDCS. These 35 individuals were then retested symptom/asthenopia scores during they watched 3D television for 65 minutes at a distance of 2.7 m with wearing BVCSL of horizontal, vertical or base down yoked prisms. A 4-point symptom-rating scale questionnaire (0=no symptom and 3=severe) was used to assess 11 symptoms (e.g., blur, diplopia, etc.) related to visual fatigue/visual discomfort. Distance and near lateral phoria were measured using Howell phoria card and vertical phoria were measured using Maddox rod. Symptoms induced by watching 3D TV were compared between wearing HDCS and BVCSL. Results: Asthenopia in watching 3D TV with wearing BVCS was significantly lower than wearing HDCS at 5, 25, 45, and 65 minutes (all p < 0.001, paired t-tests). In only refractive error power correction power group, all asthenopia was not significantly different between HDCS and BVCSL (all $p{\geq}0.05$, paired t-tests). In prism correction groups for binocular imbalance, symptoms of asthenopia, however, was significantly lower for when wearing BVCSL than when wearing HDCS (all p < 0.05). Conclusions: Correction of phoria/vergence-based binocular vision imbalance can reduce asthenopia during 3D television viewing. An individual with binocular vision imbalance need corrected/compensated glasses with appropriate prisms prior to prolonged viewing of 3D television displays to reduce asthenopia/visual fatigue.

• Science of Emotion and Sensibility
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• v.19 no.1
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• pp.61-70
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• 2016

3D visual fatigue is known as one of the most important factors that interfere the commercial success of 3D contents. Vergence-accommodation conflict, which is known to occur when an observer watches an image containing binocular disparity presented on a 3D display, has been suggested as a major cause of 3D visual fatigue. This implies that any image incorporating binocular disparity might cause 3D visual fatigue. In order to reduce 3D visual fatigue, it would be necessary to consider indirect ways of reducing 3D visual fatigue as well as eliminating the direct causes of 3D visual fatigue. We have examined the effect of the variables that are expected to affect subjective 3D visual fatigue and these variables included the relative disparity contained in an image, viewing distance and viewing angle. We have also figured out the proper levels of the variables required to minimize 3D visual fatigue. The results indicate that observers began to report significant 3D visual fatigue when the crossed disparity contained in an image exceeded 7.22' and the vertical viewing angle was larger than 15 degree.

• Journal of Broadcast Engineering
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• v.23 no.1
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• pp.74-85
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• 2018

The research investigated the interaction effect of video resolution and device luminance on the perceived characteristics, presence, and fatigue viewing virtual reality. Experiments were composed of mixed design, and the resolution and luminance were classified into three types, HD, 2K, and 4K, and 20, 60, and 100, respectively. Participants watched video of 6-minutes randomly, and responded to the questionnaire after watching each video. The results showed that no interaction effect existed. Meanwhile, there are statistically significant differences on the luminance of depth perception, the resolution of visual intervention, and the resolution of adjustment fatigue. Also, higher resolution and luminance showed higher cognitive function, presence and fatigue.

• Science of Emotion and Sensibility
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• v.13 no.4
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• pp.621-634
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• 2010

This study aimed to investigate the effects of dimensions of movie clip (2D vs. 3D), viewing orders (2D ${\to}$ 3D vs. 3D ${\to}$ 2D), and gender difference on participants' subjective fatigue, recognition for the elements in the clips, and arousal level. The results can be summarized as followings. First, subjective fatigue level was higher in the 3D condition than 2D condition, but this tendency was more clear in the 2D ${\to}$ 3D condition than in the 3D ${\to}$ 2D condition. Second, correct recognition rates were significantly higher for 3D than 2D only in the 3D ${\to}$ 2D condition. In particular, male participants showed higher correct recognition rates than female participants in the 3D clip condition, whereas female participants showed higher correct recognition rates than male participants in the 2D clip condition. Third, although 3D clips tended to induce higher level of arousal, this tendency was showed only in the 2D ${\to}$ 3D condition, which implied previous exposure to 2D clip increased the arousal level in following 3D clip than vice versa.

• Journal of Digital Contents Society
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• v.16 no.1
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• pp.127-135
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• 2015

The development of stereoscopic display hardwares and 3D authoring softwares expands its application areas from particular virtual simulation applications to general movies, games, advertising applications. However, the binocular-based 3D stereoscopic images cause fatigue to viewers. Recent performed many research results about the binocular stereoscopy's depth perception and viewers' fatigue are derived from experimental users studies. In some results, watching and making guidelines for 3D stereoscopic imaging contents are introduced. The 3D stereoscopic-related contents have the contradictory aspects, which are audiences' pursuit of a tolerable minimum fatigue and producer's its of excessive depth changes for providing viewers' immersion. This paper provides user experiments and analysis data in aspects of 3D depth changes. For use of producers, a safety zone and translational velocity of 3D depth changes are introduced. Also, on the viewer side, we present the depth change adaptation time by using an EEG device.

• Science of Emotion and Sensibility
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• v.14 no.4
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• pp.653-662
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• 2011

As technology in 3D industry has rapidly advanced, a lot of studies primarily focusing on visual function and cognition have become vigorous. However, studies on effect of 3D visual fatigue on autonomic nervous system have not less been conducted. Thus, this study was to identify and determine the effect that might have a negative influence on sympathetic nervous system, parasympathetic nervous system, and cardiovascular system. Fifteen undergraduates (female: 9, mean age: $22.53{\pm}2.55$) participated and were sat on a comfortable chair, viewing a 3D content during about 1 hour. Cardiac responses like SDNN(standard deviation of RR intervals), RMS-SD(root mean squared successive difference), and HF/LF ratios extracted from the measured PPG(Photo-PlethysmoGram) before viewing 3D were compared to those after viewing 3D. The results showed that after subjects watched the 3D, responses in sympathetic nervous system and parasympathetic nervous system were activated and deactivated, respectively relative to those before watching the 3D. The results showed that HF/LF ratio, Ln(LF), and Ln(HF) after viewing 3D were significantly reduced relative to those before viewing 3D. No significant effects were observed in SDNN and RMS-SD. Results obtained in this study showed that visual fatigue induced by watching 3D adversely influenced autonomic nervous system, and thereby reduced heart rate variability causing sympathetic nervous acceleration.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.2
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• pp.171-176
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• 2012

Purpose: This study was to compare changes in near lateral phoria and near point of convergence after viewing smartphones and monitors during short periods. Methods: 50 subjects with healthy eyes from 20s to 30s (mean age, $21.84{\pm}5.13$ years) were examined. Viewing time was set at 5 min to 20 min, and recovery time was 10 min. Near lateral phoria and near point of convergence (NPC) were examined before and after watching smartphones and monitors, and subjectively symptoms for visual fatigue were surveyed using a questionnaire before and after viewing image. Results: The tendency of phoria in viewing smartpones found more exophoric results than in viewing monitors, and both exophoric shifts were recovered after 10 min. The receded NPC in the smartphones was more remote than in the monitors. The smartpones induced more visual fatigue than the monitors. Conclusions: Sustained smartphone works induced changes in phoria and NPC, and this type of stress could cause visual fatigue. Therefore, an appropriate rest breaks can be helpful in relieving visual fatigue.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.06a
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• pp.157-159
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• 2013

3D 산업은 그 실용적인 활용가치로 인해 주목받고 있다. 안정적인 3D 시청환경을 구축하기 위해서는 구현기술의 발전이 중요한 과제이지만, 현재의 기술 수준이 제한적이기 때문에 사용자가 시청환경에 대해 주관적으로 느끼는 부분을 다루는'휴먼팩터 (Human-factor)'를 연구하는 것 또한 중요하다. 그 중 시각피로는 안정적인 3D시청환경 구축과 직결되는 중요한 문제이며, 이러한 시각피로의 주요원인은 수렴-조절 불일치 현상이다. 본 연구는 수렴-조절 불일치에 직접적인 영향을 미치는 것이 화면시차 자체가 아니라 수렴각에 영향을 미치는 응시대상의 화면시차라고 가정하였다. 따라서 응시대상의 화면시차가 3D상황에서 수렴조절 불일치를 유발하는지를 규명하기 위하여 시청자들을 대상으로 응시대상의 화면시차를 조작하면서 그것이 시각피로에 영향을 주는지를 측정하였다. 결과는 예상대로 다른 대상들보다 응시대상의 시차가 시각피로에 주요한 영향력을 준다는 것을 함축하고 있으며, 그 외에 비-응시대상과 관련된 이슈들이 논의되었다. 결론적으로, 응시대상의 시차를 적절하게 통제함으로써 사용자의 시각피로를 최소화 할 수 있으며, 이는 시각 3D 환경을 구축하는 데에 도움이 될 것이다.