Effects on visual functions during tasks of object handling in virtual environment with a head mounted display

This study examined the effects on visual functions of a prolonged handling task within the helmet-mounted display environment. Both version eye movement and accommodative response became gradually slower during the 40-min task. Although delayed presentation of display after head movement noticeably worsened both visual responses, presentation delay after hand movement did not significantly change the sluggishness of responses. Therefore it is suggested that decreasing time delay after head movement is a more important factor in order to improve human performance of handling tasks within the HMD environment.     

Comparison of visual fatigue caused by head-mounted display for virtual reality and two-dimensional display using objective and subjective evaluation

This study aimed to evaluate objective and subjective visual fatigue experienced before and after performing a visual task while using a head-mounted display for virtual reality (VR-HMD) and two-dimensional (2D) display. Binocular fusion maintenance (BFM) was measured using a binocular open-view Shack–Hartmann wavefront aberrometer equipped with liquid crystal shutters. Twelve healthy subjects performed the BFM test and completed a questionnaire regarding subjective symptoms before and after performing a visual task that induces low visually induced motion sickness (VIMS). BFM (p = .87) and total subjective eye symptom scores (p = .38) were not significantly different between both groups, although these values were significantly lower after the visual task than before the task within both groups (p < .05). These findings suggest that visual fatigue after using a VR-HMD is not significantly different from that after using a 2D display in the presence of low-VIMS VR content.

Practitioner summary: Objective and subjective evaluation of visual fatigue were not significantly different with the use of a head-mounted display for virtual reality (VR-HMD) and two-dimensional display. These results should be valuable not only to engineers developing VR content but also to researchers involved in the evaluation of visual fatigue using VR-HMD.

Abbreviations: VR: virtual reality; VR-HMD: head-mounted display for virtual reality; BFM: binocular fusion maintenance; BWFA: binocular open-view Shack–Hartmann wavefront aberrometer     

Components of the visual computer: A review of relevant technologies

Visual computing emhpasizes visibility of information of interest and direct manipulation of visible information. It has become a dominant style of computing in recent years. In this paper, we review three major technologies that provide a platform for visual computing. These technologies reflect the needs of various people who use visual computers: programmers, end users, and scientists. We begin with a discussion of important developments in visual programming and follow with discussions of visual interfaces and visualization. We conclude with a summary of visual computing's current status and identify critical areas of research that should be emphasized in future work.     

The contribution of virtual reality to research on sensory feedback in remote control

Here we consider research on the kinds of sensory information most effective as feedback during remote control of machines, and the role of virtual reality and telepresence in that research. We argue that full automation is a distant goal and that remote control deserves continued attention and improvement. Visual feedback to controllers has developed in various ways but autostereoscopic displays have yet to be proven. Haptic force feedback, in both real and virtual settings, has been demonstrated to offer much to the remote control environment and has led to a greater understanding of the kinesthetic and cutaneous components of haptics, and their role in multimodal processes, such as sensory capture and integration. We suggest that many displays using primarily visual feedback would benefit from the addition of haptic information but that much is yet to be learned about optimizing such displays.     

A curved surface display for three fingers based on human visual and tactile sensory fusion

In general, it is difficult to present tactile information because arbitrary curvatures of the curved surface and many degrees of freedom need to be realised. On the other hand, psychophysical studies have suggested that human visual and tactile sensations have an illusory fusion characteristic. This means that we can recognise curved surfaces of objects through visual and tactile sensations, even if exact tactile information is not presented. Hence, by utilising the human characteristic of sensory fusion, realisation of a curved surface display can be simplified. From such motivation, the human fusion characteristics of visual and tactile sensation are measured, and are quantitatively analysed. Based on the analysed results, a curved surface display for three fingers is developed. In the curved surface display, only four curved patterns are utilised instead of presenting many curved patterns. Performance of the developed tactile display is proved through evaluated experiments.     

基于视景仿真的加油车虚拟维修系统

阐述了维修训练的现状,并结合目前加油车在维修训练中存在的问题,提出将虚拟维修应用于加油车维修训练中。技术实现上,应用视景仿真软件Creator的层次化结构、纹理映射和LOD等技术,建立、管理和优化模型。在Vega中设计仿真程序,实现基于鼠标的虚拟维修训练操作。     

Virtual assembly technologies based on constraint and DOF analysis

Assembly constraint is an important factor for product assembly. Constraint is not only necessary for accurate locating of parts but also an important way to realize assembly operation process in virtual assembly (VA) system. In this study, to realize VA reasonably, uniform representations of assembly constraint, equivalent relation between constraint and degree of freedom (DOF), and movable DOF reduction are defined. Several algorithms including based-constraint assembly relation recognition, assembly parts location solving under free and constrained spaces, and movement navigation are developed. These algorithms have been applied to integration virtual assembly environment (IVAE) software system. An example is illustrated, and the results prove that the algorithms provide a good support for the constraint treatments in IVAE and the high consistence between virtual and real assembly process is realized.     

Effects of visual referencing on backward and forward treadmill walking in VR environments

Backward walking is used increasingly as a rehabilitation exercise for stroke and diabetic peripheral neuropathy patients to improve strength and balance. However, it is unclear how visual referencing affects backward and forward walking. In this study, we evaluated spatiotemporal gait characteristics changes due to visual referencing while backward/forward walking. Sixteen healthy young participants were recruited in this study. All participants walked for 2 min with and without visual referencing in the virtual reality environment. While walking backward participants faced the virtual reality screen similar to forward walking, but their treadmill belt direction of movement was reversed. All participants walked at their preferred speed. We found that backward walking with visual reference affected symmetry in step length (p < 0.05) and step width (p < 0.001). Backward walking increased variability in step length (p < 0.001) and COM side excursions (p < 0.01) but also increased base of support through increased step width (p < 0.02). We also found backward walking with visual reference had significantly increased double support time (p < 0.001) and reduced swing time (p < 0.001). We also found that backward walking does not predispose to slip and trip risk, thereby, reduced foot contact velocity (p < 0.0001) and increased foot clearance (p < 0.0001). The findings of this study will help understand the effects of visual reference in backward and forward walking enables clinicians to design patient-centered rehabilitation exercises.     

The impact of Web3D technologies on medical education and training

This paper provides a survey of medical applications that make use of Web3D technologies, covering the period from 1995 to 2005. We assess the impact that Web3D has made on medical education and training during this time and highlight current and future trends. The applications identified are categorized into: general education tools; tools for diagnosis; procedures training; and collaborative training. A summary of work that has been carried out to validate these tools is also included in the survey.     

Usability of the size,spacing, and operation method of virtual buttons with virtual hand on head-mounted displays

Virtual reality (VR) allows users to see and manipulate virtual scenes and items through input devices, like head-mounted displays. In this study, the effects of button size, spacing, and operation method on the usability of virtual buttons in VR environments were investigated. Task completion time, number of errors, and subjective preferences were collected to test different levels of the button size, spacing, and operation method. The experiment was conducted in a desktop setting with Oculus Rift and Leap motion. A total of 18 subjects performed a button selection task. The optimal levels of button size and spacing within the experimental conditions are 25 mm and between 5 mm and 9 mm, respectively. Button sizes of 15 mm with 1-mm spacing were too small to be used in VR environments. A trend of decreasing task completion time and the number of errors was observed as button size and spacing increased. However, large size and spacing may cause fatigue, due to continuous extension of the arms. For operation method, the touch method took a shorter task completion time. However, the push method recorded a smaller number of errors, owing to the visual push-feedback. In this paper, we discuss advantages and disadvantages in detail. The results can be applied to many different application areas with VR HMD using virtual hand interaction.     

Influence on visual function by a stereoscopic TV programme with binocular liquid crystal shutter and Hi-Vision TV display

Influence on visual functions by field sequential stereoscopic Hi-Vision TV programme with a liquid crystal shutter were investigated in 24 subjects. Ocular alignment, fusional amplitude, AC/A ratio, stereoacuity, accommodation and pupil size were measured before and after the visual load. Symptoms related to asthenopia were also examined. No significant difference were found, although two aged subjects showed large changes in a few of these functions. This type of 3-D display may not be hazardous to visual functions, although further study may be required for aged or visually handicapped people.     

3ds MAX建模与场景渲染技术在可视化设计中的应用

随着建模技术与软件的发展,三维虚拟现实技术的应用领域越来越广泛。3 d s M a x是目前最流行的专业建模、动画和图像制作软件,3ds Max在建筑可视化领域中的应用包括了室内效果图、建筑表现图及建筑动画。3ds Max所提供的场景建模、场景渲染等技术手段成为计算机辅助设计的重要内容。     

Effects of increasing visual load on aurally and visually guided target acquisition in a virtual environment

The aim of the present study is to investigate interactions between vision and audition during a target acquisition task performed in a virtual environment. We measured the time taken to locate a visual target (acquisition time) signalled by auditory and/or visual cues in conditions of variable visual load. Visual load was increased by introducing a secondary visual task. The auditory cue was constructed using virtual three-dimensional (3D) sound techniques. The visual cue was constructed in the form of a 3D updating arrow. The results suggested that both auditory and visual cues reduced acquisition time as compared to an uncued condition. Whereas the visual cue elicited faster acquisition time than the auditory cue, the combination of the two cues produced the fastest acquisition time. The introduction of secondary visual task differentially affected acquisition time depending on cue modality. In conditions of high visual load, acquiring a target signalled by the auditory cue led to slower and more error-prone performance than acquiring a target signalled by either the visual cue alone or by both the visual and auditory cues.     

The application of augmented reality technologies for the improvement of occupational safety in an industrial environment

In many branches of industry, occupational safety experts identified two main causes of worker injuries related to the usage of modern electro-mechanical machines and systems: inadequate training and insufficient work experience, and monotonicity of the tasks often performed repeatedly. In this paper, we present a system based on augmented reality (AR) technologies that can be useful in reducing these factors of risk at work and decreasing the error rate and preventing injuries. The system that is implemented on mobile devices is intended to project augmented reality instructions directly at the work place. A worker is led by the AR-system step by step through various work and safety procedures that should be performed. Each procedure consists of steps specified by a series of instructions accessed through an interactive check list. To ensure the safeness, if a confirmation is missing because of a skipped, incompletely, or wrongly performed step of a procedure, the AR-system blocks further implementation of the procedure and returns the worker to the previous step until the correct actions are carried out. At the same time, interactive work with the checklist breaks the monotonicity of the job. The system is personalized according to skills of a worker by taking into account his professional training and work experience. Depending on that it is determined the amount of data to be displayed to a worker helping even less skilled workers to perform a task.As a case study, the proposed approach is implemented as an instructional and occupational safety system for work at a universal lathe, which is an element of many technological processes of Thermal Power Plant Ugljevik in the Republika Srpska, Bosnia and Herzegovina, where this AR-system was experimentally implemented and verified.     

Effects of display vibration and whole-body vibration on visual performance

Fifteen subjects performed a numeral reading task during (a) vibration of the display, (b) vibration of the subject, (c) simultaneous vibration of both subject and display. Sinusoidal motion at eleven frequencies (0·5 to 5·0 Hz) was presented at five acceleration magnitudes (1·0 to 2·5ms^?2 r.m.s.). Measures of reading time and reading error showed that for all except the highest frequencies, vibration of the display resulted in the poorest performance. Simultaneous whole-body-and-display vibration produced least performance decrement. The effects of both the viewing conditions and the vibration frequency are discussed in relation to known characteristics of the visual system.     

VirSchool: The effect of background music and immersive display systems on memory for facts learned in an educational virtual environment

Game technology has been widely used for educational applications, however, despite the common use of background music in games, its effect on learning has been largely unexplored. This paper discusses how music played in the background of a computer-animated history lesson affected participants’ memory for facts. A virtual history lesson was presented to participants with different background stimuli (music or no-music) to test the effect of music on memory. To test the role of immersion on memory and its possible relationship to the music, two different display systems (3-monitor display system or immersive Reality Center) were used in the study. Overall, participants remembered a significantly higher number of facts using the 3-monitor display system, particularly if no background music was played in the second half of the history lesson. Conversely, for participants using the Reality Center, significantly higher recall of facts was found when participants listened to music in the second half of the history lesson. Cognitive load/overload and (un-)familiarity with the technology are offered as explanations.     

刚体破碎特效仿真研究

破碎是真实世界中普遍存在的物理现象,刚体破碎仿真也在各领域中被广泛应用.本文分别从基于物理和基于非物理的建模方法产生的不同刚体破碎特效,阐述分析刚体破碎仿真的研究现状,结合当下研究和现存问题给出相关建议,并对下一步的刚体破碎研究做指引.     

基于VRML的远程教育虚拟实验室的研究

该文分析了VRML与同类技术相比的一些特点，并详细讨论了用VRML实现—虚拟实验室的关键方法。指出了简单的交互可用传感器节点，通过事件和路由来实现，复杂的交互可用Script节点，通过引入JAVA程序来实现。     

列车运行视景仿真及险情特效的实现

介绍了工具软件Multigen Creator和Vega的特点,并结合轨道交通列车运行仿真视景的实例说明利用Multigen Creator和Vega软件创建实时仿真程序的过程.在仿真程序的创建过程中,探讨了列车运行过程中突发险情以及天气特效的实现方法.仿真结果表明,基于Multigen Creator/Vega的列车运行仿真系统取得了很好的效果.