Huang Ying-Yin, Menozzi Marino
Department of Industrial Engineering and Management, National Taipei University of Technology, Taipei, 10608, Taiwan.
Human Factors Engineering, Department of Health Sciences and Technology, ETH, Zürich, Switzerland.
Appl Ergon. 2022 Jul;102:103746. doi: 10.1016/j.apergo.2022.103746. Epub 2022 Mar 12.
In augmented reality (AR), virtual information is optically combined with the physical environment. In the most frequently used combination technique, optical settings in AR depart from the settings in natural viewing. Depending on the combination of viewing distances of the virtual task and its physical background, this deviation may lower visual performance and cause visual disturbance symptoms. The so-called vergence-accommodation conflict (VAC) has been identified as a cause for the visual disturbance symptoms in AR. In this study, for various distance combinations, the performance and symptoms when performing a search task displayed in a see-through head-mounted display (AR HMD, HoloLens 1st generation, Microsoft, USA) was investigated. The search task was displayed at a virtual distance of either 200 cm or 30 cm, and the real background was viewed either at a distance of 200 cm or 30 cm. Three combinations of viewing distances for the background and the virtual task were studied: 200 cm/200 cm, 200 cm/30 cm, and 30 cm/30 cm. Results revealed that both performance and visual disturbance symptoms depend on the combination of the viewing distances of the physical background and the virtual task. When the physical background was viewed at a distance of 200 cm, younger participants showed a significantly better search performance and reported stronger symptoms compared with older participants, no matter whether the virtual task was performed at 30 cm or at 200 cm. However, with the physical background at a distance of 30 cm, the performance of the younger group dropped to the level of the performance of the older group, and younger participants tended to report a stronger increase in visual disturbance symptoms compared with the older participants. From the AR HMD technology used in this study, it can be concluded that a near viewing distance of the virtual task does not cause a negative impact on performance and visual disturbance symptoms, provided any physical background seen through the AR HMD is not at a near viewing distance. The findings indicate that the VAC, which persists in augmented and virtual reality, depends, in addition to the physical component evaluating the optical distance, on a cognitive component evaluating the perceived distance. AR settings should therefore also be evaluated in terms of possible effects on perceived distance.
在增强现实（AR）中，虚拟信息与物理环境进行光学融合。在最常用的融合技术中，AR的光学设置与自然观看时的设置不同。根据虚拟任务及其物理背景的观看距离组合，这种偏差可能会降低视觉性能并导致视觉干扰症状。所谓的辐辏-调节冲突（VAC）已被确定为AR中视觉干扰症状的一个原因。在本研究中，针对各种距离组合，研究了在透视式头戴式显示器（AR HMD，第一代HoloLens，美国微软公司）中执行搜索任务时的性能和症状。搜索任务显示在200厘米或30厘米的虚拟距离处，真实背景则在200厘米或30厘米的距离处观看。研究了背景和虚拟任务的三种观看距离组合：200厘米/200厘米、200厘米/30厘米和30厘米/30厘米。结果显示，性能和视觉干扰症状均取决于物理背景和虚拟任务的观看距离组合。当物理背景在200厘米的距离观看时，无论虚拟任务是在30厘米还是200厘米处执行，年轻参与者的搜索性能明显更好，并且报告的症状比年长参与者更强烈。然而，当物理背景在30厘米的距离时，年轻组的性能下降到与年长组相同的水平，并且年轻参与者报告的视觉干扰症状增加幅度往往比年长参与者更大。从本研究中使用的AR HMD技术可以得出结论，只要通过AR HMD看到的任何物理背景不在近观看距离，虚拟任务的近观看距离不会对性能和视觉干扰症状产生负面影响。研究结果表明，在增强现实和虚拟现实中持续存在的VAC，除了评估光学距离的物理成分外，还取决于评估感知距离的认知成分。因此，AR设置也应根据对感知距离的可能影响进行评估。
