Eye-strain and changes in accommodation of the eye and in visual evoked potential following quantified visual load

The measurements were made of the muscular contractions and relaxations of accommodation (infrared optometer) and of visual evoked potential (VEP) (photic stimulation) before and after one hour's visual load, checking calculations (1800 questions/hour and 900 questions/hour). The results showed that the relaxation time in accommodation lengthened and the latency of the positive wave appearing at about 100 ms in VEP increased with the increase in visual load. In addition, the complaint rate for eye-strain was higher in the group given heavier visual work. In this group, there was no significant difference in amplitude of VEP before and after the visual task. The difference in the relaxation time before and after the visual task tended to be negatively correlated to the difference in amplitude of VEP and positively related to that in the latency. In the group given lighter visual work there were significant differences in the latency and the amplitude of VEP before and after the visual task, neither were correlated to the difference in the relaxation time. These results suggest that not only peripheral hypofunction but also the decrease of centrencephalic activity level may be responsible for the development of eye-strain caused by visual tasks.     

Visual search tasks: measurement of dynamic visual lobe and relationship with display movement velocity

Visual lobe is a useful tool for predicting visual search performance. Up till now, no study has focused on dynamic visual lobe. This study developed a dynamic visual lobe measurement system (DVLMS) that could effectively map dynamic visual lobe and calculate visual lobe shape indices. The effects of display movement velocity on lobe shape indices were examined under four velocity conditions: 0, 4, 8 and 16 deg/s. In general, with the increase of display movement velocity, visual lobe area and perimeter became smaller, whereas lobe shape roundness, boundary smoothness, symmetry and regularity deteriorated. The elongation index was not affected by velocity. Regression analyses indicated that display movement velocity was important in determining dynamic visual lobe shape indices. Dynamic visual lobe provides another option for better understanding dynamic vision, in addition to dynamic visual acuity. Findings of this study can provide guidelines for analysing and designing dynamic visual tasks.

Practitioner Summary: Dynamic visual lobe is important in reflecting the visual ability of searching for a moving target. We developed a dynamic visual lobe measurement system (DVLMS) and examined display movement velocity’s effects on lobe shape. Findings revealed that velocity was a key factor affecting dynamic visual lobe shape indices.     

Investigation of visual and game-playing performance under different genders,display and operation interfaces

Technological progress has led to 3D displays becoming a trend in the market, yet few studies have evaluated 3D techniques in head-mounted displays (HMD) under different topics simultaneously, such as gender and operation interfaces. This study investigated these research issues to examine the effect of gender (male, female), display interface (2D TV, 3D HMD), and operation interface (joystick, keyboard) on usability, accuracy, change of critical flicker frequency (change of CFF), Simulator Sickness Questionnaire (SSQ), and iGroup Presence Questionnaire (IPQ). Thirty participants with no NBA2K15 basketball game-playing experience were recruited in the experiment. The results showed significant effects of gender on accuracy, usability, and change of CFF, where males demonstrated higher accuracy, lower usability, and lower visual fatigue. In addition, display interface had significant effects on usability, SSQ and IPQ. The 2D TV was associated with higher usability and lower SSQ and IPQ. Furthermore, the operation interface had significant effects on accuracy, usability, change of CFF, and IPQ. The joystick led to a higher usability and IPQ but a lower change of CFF. The results provide suggestions to game players that choosing 2D TVs with joysticks generates greater usability. In addition, although they achieved a higher presence, players also had greater visual fatigue when wearing HMDs. This study concluded that males have better performance in accuracy and visual fatigue while females have better usability when playing basketball games.     

Using electromyography responses to investigate the effects of the display type,viewing distance,and viewing time on visual fatigue

The rapid success of 3D display technology and daily accessibility to 3D images has greatly increased the interest in such applications for a wide range of fields. This paper compares the effects of watching movies with 2D and 3D displays depending on the viewing distance (3H vs. 6H, where H is the height of the screen) and viewing time to determine the visual fatigue using electromyography (EMG) in terms of the percentage of maximum voluntary contraction (%MVC) of the orbicularis oculi (OO) muscle activity and a subjective visual discomfort score. Twenty healthy male university students with a mean age of 27.7 ± 2.53 years participated in this study as volunteers. None had color blindness, and all had normal vision acuity. A mixed-measures design was performed. The results showed that the viewing time and distance had significant effects on the %MVC and OO muscle activity depending on the display type. Watching the 3D display from a short viewing distance produced significantly high visual fatigue compared to watching the 2D display from a short viewing distance. However, the 3D display seemed to be less stressful than the 2D display at long viewing distances.     

Occlusion as a measure for visual workload: an overview of TNO occlusion research in car driving

A process-oriented approach by systematically studying driver performance, distraction, and workload is the way to go for assessing safety effects of new telematics applications in vehicles. These systems may strive for drivers' attention and possibly lead to distraction from the primary task. Visual occlusion techniques appear to be an effective means of studying drivers' visual information processing performance. Studies to illustrate this include identifying the minimum visual information drivers need for driving (asking for visual information) and the evaluation of driver support systems such as heading control and adaptive cruise control with respect to visual workload. In other applications the occlusion technique is used to exclude 'visual array' information from the optic flow field. The temporary exclusion of part of the visual field of view was applied in evaluating the effects of different types of driver's side rearview mirrors.     

The correlation between visual fatigue and duration of viewing as assessed by brain monitoring

Duration of viewing was considered as one of the most important factors of 3D visual fatigue. However, their relationship was not well studied. We proposed to use brain monitoring techniques to reveal more details about the variety of brain activity while watching three‐dimensional (3D) content. We investigated the spectral patterns in the electroencephalogram related to various duration of viewing and showed the power spectral density varied significantly along with the development of fatigue over occipital lobe, parietal lobe, and right frontal lobe. Moreover, we first described the trend of brain activity during 3D content viewing and revealed the location of significant components related to 3D visual fatigue. We believe that the absolute power describes more information and may be a better indicator of 3D visual fatigue assessment compared with relative power. We also first revealed the cortex location that is related to 3D visual fatigue. Our findings may help to define appropriate electroencephalogram features for online 3D visual fatigue detection while participants viewing 3D content.     

Visual effects of the luminance surrounding a computer display

The luminance surrounding a computer display can potentially reduce visibility of the display (disability glare), result in sensations of discomfort (discomfort glare) and result in transient adaptation effects from fixating back and forth between the two luminance levels. The study objective was to measure the effects of surround luminance levels upon these functions in younger and older adults to determine recommended surround luminance levels. The younger age group comprised 20 subjects (mean age 27.9 years, range 23 – 39) and the older group 17 subjects (mean age 55.5 years, range 47 – 63). The central task was presented with luminance of 91 cd/M², tested surround luminance levels were 1.4, 2.4, 8.9, 25.5, 50, 91, 175, 317, and 600 cd/M². Disability glare was tested with low contrast (20%) visual acuity charts, transient adaptation was tested with a task that required regular fixation between the two luminance levels, discomfort was measured with a questionnaire after reading stories with different surround luminance levels, and preferred luminance was measured by method of adjustment. The surround luminance significantly affected transient adaptation (p < 0.0001), optimal performance occurred at 50 cd/M² and above for the young group and at 91 cd/M² and above for the older group. Neither low contrast acuity (disability glare) nor symptoms when reading were significantly affected by surround luminance. There was wide variation in preferred surround luminance; however, average preferred surround luminance was 86.9 cd/M² for the young group and 62.2 cd/M² for the older group, slightly below the central luminance of 91 cd/M². The effects of the surround luminance within the tested range are not large; however, the data show that the lowest surround luminance levels should be avoided and that surround luminance levels at or slightly below that of the central task are preferred.     

城市色彩与视觉生态

当人们一谈到世界上富有特色的城市,随之而来的就是对该城市色彩的联想,色彩往往比造型更具有视觉冲击力和吸引力,良好的城市色彩构成能使居于其中的人们得到愉悦的视觉享受,反之则会带来视觉环境污染。     

VB6.0在LED汉字信息显示系统中的应用

本文介绍了VB6．0在LED汉字信息显示系统的应用中如何进行实时汉字点阵提取及串行通讯的方法，讨论了程序设计要点，给出了相应的程序代码。     

“项目教学法”在Visual FoxPro教学中的应用

“项目教学法”以建构主义为理论依据，强调以学生的主动学习为主。在Visual FoxPro教学中实施项目教学法．对于提高课堂教学效果，培养学生的动手能力有积极作用。     

Spectral influence of the normal LCD,blue-shifted LCD,and OLED smartphone displays on visual fatigue: A comparative study

In this study, we investigated the influence of the light spectra of the normal LCD, blue-shifted LCD, and OLED smartphone displays on visual fatigue based on subjective and objective measurements. The illuminance of the retinal photoreceptors was calculated for the three displays to quantify the components of the light spectra. The results showed that the accumulated visual fatigue decreased for the display with lower retinal illuminances of the S-, M-, and L-cones, and ipRGCs when the luminance and CCT were the same. In addition, the display with larger retinal illuminances of the M- and L-cones induced more visual fatigue related to dry eye. Hence, a slight shift of the blue light peak toward a longer wavelength is recommended for reducing visual fatigue. Furthermore, an evaluation model of the overall visual fatigue level is proposed.     

Measuring the likelihood of VR visual fatigue through ocular biomechanics

Immersion in virtual reality is still linked to symptoms of visual fatigue such as eye strain, dizziness, and overall discomfort. Studies have investigated visual fatigue through pre- and post-immersion tests of the visual function. In this work, we extend on our previous study and derive a visual fatigue likelihood metric using biomechanical analysis. Previously, we have investigated the effect of VR on the vergence system during immersion. The proposed visual fatigue metric exhibited a significant correlation to vergence angle variability which was previously linked to vergence accommodation conflict in VR. We also discuss subjective feedback and its relationship with the proposed visual fatigue metric.     

Measuring the effects of visual demand on lateral deviation: a comparison among driver's performance indicators

In this study we compare the efficacy of three driver's performance indicators based on lateral deviation in detecting significant on-road performance degradations while interacting with a secondary task: the High Frequency Component of steering wheel (HFC), and two indicators described in ISO/DIS 26022 (2007): the Normative and the Adapted Lane Change Test (LCT). Sixteen participants were asked to perform a simulated lane-change task while interacting, when required, with a visual search task with two levels of difficulty. According to predictions, results showed that the Adapted LCT indicator, taking into consideration individual practices in performing the LCT, succeeded in discriminating between single and dual task conditions. Furthermore, this indicator was also able to detect whether the driver was interacting with an easy or a difficult secondary task. Despite predictions, results did not confirm Normative LCT and HFC to be reliable indicators of performance degradation within the simulated LCT.     

Analysis of visual acuity and motion resolvability as measures for optimal visual perception of the workspace

For working tasks with high visual demand, ergonomic design of the working stations requires defining criteria for comparative evaluation and analysis of the visual perceptibility in different regions of the workspace. This paper provides kinematic models of visual acuity and motion resolvability as adopted measures of visual perceptibility of the workspace. The proposed models have been examined through two sets of experiments. The first experiment is designed to compare the models outputs with those from experiments. Time measurements of the participants’ response to visual events are employed for calculation of the perceptibility measures. The overall comparison results show similar patterns and moderate statistical errors of the measured and kinematically modeled values of the parameters. In the second experiment, the proposed set of visual perceptibility measures are examined for a simulated industrial task of inserting electronic chips into slots of a working table, resembling a fine assembly line of transponders manufacturing. The results from ANOVA tests for the visual acuity and the motion resolvability justify the postures adopted by the participants using visual perceptibility measures for completing the insertion tasks.     

基于Visual FoxPro 6.0化工实验数据处理软件的开发

介绍了化工实验数据处理软件的内容、设计思想和功能特点，整个软件使用方便，界面友好，具有传统方法无法比拟的优势。     

基于Visual Foxpro的北京奥运会倒计时显示牌的设计

详细分析与探讨了用Visual Foxpro设计距2008北京奥运会开幕倒计时显示牌的方法和步骤。首先在设计北京奥运会倒计时显示牌表单界面及相关属性的基础上,阐明了北京奥运会倒计时显示牌的功能目标,进一步分析相应对象相关事件的基本过程,并提供相应的Visual Foxpro程序代码。     

基于Visual Foxpro的北京奥运会倒计时显示牌的设计

详细分析与探讨了用Visual Foxpro设计距2008北京奥运会开幕倒计时显示牌的方法和步骤。首先在设计北京奥运会倒计时显示牌表单界面及相关属性的基础上,阐明了北京奥运会倒计时显示牌的功能目标,进一步分析相应对象相关事件的基本过程,并提供相应的Visual Foxpro程序代码。     

基于TDL的测试系统可视化对象模型构建技术

简介：随着航空武器装备试验测试的不断发展,分布式、独立的测试系统已越来越不能满足试验测试任务的需求,急需建立一种多区域联合试验测试技术体系架构,实现跨区域的联合试验与测试。本文针对多区域联合试验中的对象模型构建技术进行研究,采用基于TDL和MagicDraw的可视化建模技术对测试系统对象模型进行可视化建模,形成靶场运行控制平台可调用的组件化模型,并对典型飞行试验测试系统对象模型组件进行了调用、部署与功能测试。实验结果表明组件化的测试系统对象模型构建技术能够贴切的表述测试系统的功能特点,同时能够很好的与实物模型进行关联,测试系统对象模型内部的数据通信延时不大于150ms,满足未来联合试验场构建需求。     

基于Visual Foxpro的成绩统计分析的设计

详细分析与探讨了用Visual Foxpro设计学生成绩统计分析表的方法和步骤.首先在设计成绩统计分析袁单界面及相关属性的基础上,阐明了学生成绩统计分析表的功能目标,进一步分析相应对象相关事件的基本过程,并提供相应的Visual Foxpro程序代码.