虚拟驾驶员视觉感知模型研究

视觉是驾驶员获得驾驶信息的主要通道,虚拟驾驶员的视觉感知模型是驾驶行为建模与仿真的重要内容,直接影响驾驶行为仿真的逼真度。介绍了四种视觉感知建模方法,根据视觉感知系统的反馈性和选择性,建立了视觉感知模型。在模型中,将视觉感知分为感觉和知觉两个过程,并引入了注意力、记忆力、驾驶疲劳和驾驶经验等因素,对每个因素进行分析。通过对虚拟驾驶员视觉感知模型的仿真实验,验证了该模型的可靠性和有效性,为驾驶行为研究提供了基础。     

From visual simulation to virtual reality to games

During the past decades, the virtual reality community has based its development on a synthesis of earlier work in interactive 3D graphics, user interfaces, and visual simulation. Currently, the VR field is transitioning into work influenced by video games. Because much of the research and development being conducted in the games community parallels the VR community's efforts, it has the potential to affect a greater audience. Given these trends, VR researchers who want their work to remain relevant must realign to focus on game research and development. Leveraging technology from the visual simulation and virtual reality communities, serious games provide a delivery system for organizational video game instruction and training.     

Depth perception in shuffleboard: Depth cues effect on depth perception in virtual and augmented reality system

The virtual reality (VR) and augmented reality (AR) applications have been widely used in a variety of fields; one of the key requirements in a VR or AR system is to understand how users perceive depth in the virtual environment and AR. Three different graphics depth cues are designed in shuffleboard to explore what kind of graphics depth cues are beneficial for depth perception. We also conduct a depth‐matching experiment to compare performance in VR and AR systems using an optical see‐through head‐mounted display (HMD). The result shows that the absolute error increases as the distance becomes farther. Analysis from the inverse of distance shows that box depth cues have a significant effect on depth perception, while the points depth cues and line depth cues have no significant effect. The error in diopter in AR experiment is lower than that in VR experiment. Participants in the AR experiment under medium illuminance condition have less error than those under low and high illuminance conditions. Men have less error than women in certain display conditions, but the advantage disappears when there is a strong depth cue. Besides, there is no significant effect of completion time on depth perception.     

Three views of virtual reality: nonimmersive virtual reality

Nonimmersive virtual reality (VR), which places the user in a 3D environment that can be directly manipulated with a conventional graphics workstation using a monitor, a keyboard; and a mouse, is discussed. The scene is displayed with the same 3D depth cues used in immersive VR: perspective view, hidden-surface elimination, color, texture, lighting, shading and shadows. As in immersive VR, animation and simulation are interactively controlled in response to the user's direct manipulation. Much of the technology used to support immersive and nonimmersive VR is the same. They use the same 3D modeling and rendering and many of the same interaction techniques. The advantages and applications of nonimmersive VR systems are discussed. Immersive and nonimmersive VR systems are compared and hybrid possibilities are reviewed     

Perceiving affordances in virtual reality: influence of person and environmental properties in perception of standing on virtual grounds

We evaluated the perception of affordances in virtual environments (VE). In our work, we considered the affordances for standing on a virtual slanted surface. Participants were asked to judge whether a virtual slanted surface supported upright stance. The objective was to evaluate whether this perception was possible in virtual reality (VR) and comparable to previous works conducted in real environments. We found that the perception of affordances for standing on a slanted surface in virtual reality is possible and comparable (with an underestimation) to previous studies conducted in real environments. We also found that participants were able to extract and to use virtual information about friction in order to judge whether a slanted surface supported an upright stance. Finally, results revealed that the person’s position on the slanted surface is involved in the perception of affordances for standing on virtual grounds. Taken together, our results show quantitatively that the perception of affordances can be effective in virtual environments and influenced by both environmental and person properties. Such a perceptual evaluation of affordances in VR could guide VE designers to improve their designs and to better understand the effect of these designs on VE users.     

The influence of attentional engagement and spatial characteristics on time perception in virtual reality

Virtual Reality - Virtual reality (VR) is a simulation tool that is being used extensively to study the effects of training and perception. However, several studies have shown that some aspects of...     

虚拟培训中的虚实联动技术

针对传统培训方式的不足,提出了虚实联动的培训方式.通过构建虚拟设备,硬件可编程逻辑控制器(PLC)、PC、虚拟设备三者之间的通信,实现虚拟设备和实体设备之间的联系,并且通过现场控制系统采集实体设备运行数据,将实体设备运行和故障等信息在虚拟设备中实时表现出来,拓展了虚拟培训的新思路.以喷印机虚拟联动系统为例论述了虚拟联动技术的必要性和可行性.     

Game engine virtual reality with CaveUT

CaveUT, an open source freeware project, uses game technology to make projection-based virtual reality affordable and accessible. The CaveUT works well for low-cost displays and supports real-time spatial tracking and stereographic imaging. Computer games with the most advanced simulation and graphics usually employ a game engine, a commercially available software package that handles basic functions. Based on the Unreal Tournament the CaveUT game engine gives developers a high-performance, low-cost VR alternative. VR applications developed with CaveUT inherit all the Unreal Engine's capabilities along with Unreal Tournament's authoring support, open source code, content library, and large user community.     

Automating virtual reality

The author discusses some applications of virtual reality and the limitations of interactivity. He considers how automatic simulated behavior minus the application judgment of direct human participation is already evolving in computer animation. In traditional animation, the animator explicitly controls every action of the characters, provides every cause, and determines every effect. While we think of virtual reality as the ultimate interactive technology, it is likely that only new tasks will be purely interactive. As applications are better understood, the ratio of interactive to automated processing will go down. We can expect anthropomorphic simulated humans to work on simulated projects in not necessarily visible virtual worlds     

Real-time markerless tracking for augmented reality: the virtual visual servoing framework

Tracking is a very important research subject in a real-time augmented reality context. The main requirements for trackers are high accuracy and little latency at a reasonable cost. In order to address these issues, a real-time, robust, and efficient 3D model-based tracking algorithm is proposed for a "video see through" monocular vision system. The tracking of objects in the scene amounts to calculating the pose between the camera and the objects. Virtual objects can then be projected into the scene using the pose. In this paper, nonlinear pose estimation is formulated by means of a virtual visual servoing approach. In this context, the derivation of point-to-curves interaction matrices are given for different 3D geometrical primitives including straight lines, circles, cylinders, and spheres. A local moving edges tracker is used in order to provide real-time tracking of points normal to the object contours. Robustness is obtained by integrating an M-estimator into the visual control law via an iteratively reweighted least squares implementation. This approach is then extended to address the 3D model-free augmented reality problem. The method presented in this paper has been validated on several complex image sequences including outdoor environments. Results show the method to be robust to occlusion, changes in illumination, and mistracking.     

Acoustic Simulation with Dynamic Mechanisms in Virtual Reality

Although most investigators have realized the importance of acoustic simulation in sophisticated VR systems,large computational load involved in this process often contradicts the requirements of real-time interaction,which in return bring on applying the expensive hardware or VR-specific workstations to this area.In order to reduce the computational cost and try to realize the real-time acoustic simulation in software with (or even without)some low-cost hardware,this paper proposes some dynamic mechanisms which can be used as possible strategies embedded into acoustic simulation in VR.Preliminary implementation of those mechanisms has proved to be fairly effective.     

Japanese activities in virtual reality

Most virtual reality hardware in Japan has been imported from the US, and the large-scale applications have focused on games, where Sega Enterprises and Nintendo remain the market leaders. In addition to its successful home video and arcade machines businesses, Sega is moving aggressively into the amusement-park ride market. Outside these markets, Matsushita plans to release three commercial products in spring 1994. One is an immersive system for product showrooms to help Japanese home owners visualize new kitchens before ordering them. Another is a massage chair that uses VR images and sound to help relax users. The third is an exercise bicycle that lets the user cycle through a 3D virtual world while exercising. Many Japanese companies are interested in VR technology as a problem-solving tool. They are making progress in its use in equipment operation. They also realize that the ability to operate devices intuitively by ordinary gesture-like motions can be exploited in many practical fields. This ability could make human-machine interfaces easier, even if these interfaces fall short of outright VR. This article reviews a few recent industry and academic research projects. The current worldwide recession has flattened the overall rate of growth in Japanese research and development spending. Nevertheless, Japan reportedly has approximately 20 major VR research projects, mostly emphasizing communication. Japanese emphases on long-term planning and on targeting development toward specific products are their strengths in this emerging technology     

European activities in virtual reality

We survey European activities in virtual reality, with an emphasis on selected efforts in architecture and sound, telepresence, scientific visualization, simulation, software design, and entertainment. This article surveys European activities and funding for VR with two caveats: First, nearly a year separates writing and publication. For most scientific fields, this publication delay for survey material would be minimal: for virtual reality, significant changes might have since occurred in some programs. We took advantage of the revision period to upgrade our information and the references as much as possible. Second, some long standing, significant European efforts go unmentioned as outside the scope of our short survey or as duplicates of others included. Despite the limitations, this sampling of Europe's leading efforts collectively gives an accurate snapshot of current European activity     

Seamless interaction in virtual reality

Jot is a novel research interface for virtual reality modeling. This system seamlessly integrates and applies a variety of virtual and physical tools, each customized for specific tasks. The Jot interface not only moves smoothly from one tool to another but also physically and cognitively matches individual tools to the tasks they perform. In particular, we exploit the notion that gestural interaction is more direct, in many cases, than traditional widget based interaction. We also respect the time tested observation that some operations-even conceptually three dimensional ones-are better performed with 1D or 2D input devices, whereas other operations are more naturally performed using stereoscopic views, higher DOF input devices, or both. Ultimately we strive for a 3D modeling system with an interface as transparent as the interaction afforded by a pencil and a sheet of paper. For example, the system should facilitate the tasks of drawing and erasing and provide an easy transition between the two. Jot emerged from our previous work on a mouse based system, called Sketch, for gesturally creating imprecise 3D models. Jot extends Sketch's functionality to a wider spectrum of modeling, from concept design to detailed feature based parametric parts. Jot also extends the interaction in Sketch to better support individual modeling tasks. We extended Sketch's gestural framework to integrate interface components ranging from traditional desktop interface widgets to context sensitive gestures to direct manipulation techniques originally designed for immersive VR     

An objective measure for the visual fidelity of virtual reality and the risks of falls in a virtual environment

Despite decades of development of virtual reality (VR) devices and VR’s recent renaissance, it has been difficult to measure these devices’ effectiveness in immersing the observer. Previously, VR devices have been evaluated using subjective measures of presence, but in this paper, we suggest that postural stability can be used to objectively assess visual fidelity of VR headsets. We validated this measure by testing known differences between the devices. This study also aimed to determine the stability of healthy participants, while in a stable virtual world, compared to eyes-open and eyes-closed conditions and therefore provide a standard of safety requirements for future experimentation. Participants’ ability to maintain a stable centre of pressure was measured using a Wii Balance Board, covered by a foam pad. Stability in eyes-open and eyes-closed conditions was compared with: (1) an iPod Touch in a simple Google cardboard style headset, (2) the Oculus Rift Development Kits (DK) DK1, DK2, with and without the tracking of linear head movements, and (3) the Samsung Gear VR. With a stable VR visual stimulus, the eyes-open condition allowed for significantly greater postural stability than the other conditions, which supports the validity of posturography as a measure of visual fidelity. Further, the iPod Touch, with its narrow field of view and rudimentary software, was significantly less effective at destabilising participants with visual perturbations than the other headsets, with their wider field of view and time warping. Unexpected results are discussed with respect to the possible limitations of the experimental design.     

Intelligent virtual environments for virtual reality art

The development of virtual reality (VR) art installations is faced with considerable difficulties, especially when one wishes to explore complex notions related to user interaction. We describe the development of a VR platform, which supports the development of such installations, from an art+science perspective. The system is based on a CAVE™-like immersive display using a game engine to support visualisation and interaction, which has been adapted for stereoscopic visualisation and real-time tracking. In addition, some architectural elements of game engines, such as their reliance on event-based systems have been used to support the principled definition of alternative laws of Physics. We illustrate this research through the development of a fully implemented artistic brief that explores the notion of causality in a virtual environment. After describing the hardware architecture supporting immersive visualisation we show how causality can be redefined using artificial intelligence technologies inspired from action representation in planning and how this symbolic definition of behaviour can support new forms of user experience in VR.     

Subjective visual vertical in virtual reality (Curator SVV): validation and normative data

Subjective visual vertical (SVV) assesses the ability to perceive verticality, which is a measure of vestibular otolithic function. Vestibular lesions influence this perception of verticality. We developed a method using virtual reality (VR) display and an Android software application named ‘Curator SVV’. The virtual reality SVV (Curator SVV) consisted of ten readily identifiable artworks projected by a Samsung phone S6 which is inserted into a virtual reality headset. In the first study, 20 patients had there SVV assessed with two devices: (1) a commercially available SVV measurement device (VestiTest^®) and (2) a virtual reality SVV using the Curator SVV application. In a second study, 32 healthy subjects had their SVV assessed by the Curator SVV application whilst sitting in a chair. In the first study, there was no significant difference (p = 0.44, paired t test and p = 0.01, test of equivalence) between results obtained by Curator SVV and the commercially available device. In the second study, the average angle measured for healthy subjects was 0.00° ± 0.85°. The normal range (mean ± 2 SD) was ± 2° in standard upright position. We were able to demonstrate that the Curator SVV can be readily employed as an objective, non-invasive and affordable means of assessing otolith function in the clinical context. We validated this novel methodology by finding strong quantitative parity between a standard commercial SVV unit and the VR Curator SVV method. Our very lightweight and mobile device can be employed in clinical contexts including at the bedside and in different head and body positions.     

Two-handed assembly with immersive task planning in virtual reality

Assembly modelling is the process of capturing entities and activity information related to assembling and assembly. Currently, most CAD systems have been developed to ease the design of individual components, but are limited in their support for assembly designs and planning capability, which are crucial for reducing the cost and processing time in complex design, constraint analysis and assembly task planning. This paper presents a framework of a two-handed virtual assembly (VA) planner for assembly tasks, which coordinates two hands jointly for feature-based manipulation, assembly analysis and constraint-based task planning. Feature-based manipulation highlights the important assembling features (e.g. dynamic reference frames, moving arrow, mating features) to guide users for the ease of assembly and in an efficient and fluid manner. The users can freely navigate and move the mating pair along the collision-free path. The free motion of two-handed input in assembly is further restricted to the allowable motion guided by the constraints recognised on-line. The allowable motion in assembly is planned by the logic steps derived from the analysis of constraints and their translation in the progress of assembly. No preprocessing or predefined assembly sequence is necessary since the planning is produced in real-time upon the two-handed interactions. Mating features and constraints in databases are automatically updated after each assembly to simplify the planning process. The two-handed task planner has been developed and experimented for several assembly examples including a drill (12-parts) and a robot (17-parts). The system can be generally applied for the interactive task planning of assembly-type applications.     

基于虚拟现实技术的移动机器人视觉伺服控制系统设计

为了有效确保移动机器人视觉伺服控制效果,提高移动机器人视觉伺服控制精度,设计了基于虚拟现实技术的移动机器人视觉伺服控制系统。通过三维视觉传感器和立体显示器等虚拟环境的I/O设备、位姿传感器、视觉图像处理器以及伺服控制器元件,完成系统硬件设计。从运动学和动力学两个方面,搭建移动机器人数学模型,利用标定的视觉相机,生成移动机器人实时视觉图像,通过图像滤波、畸变校正等步骤,完成图像的预处理。利用视觉图像,构建移动机器人虚拟移动环境。在虚拟现实技术下,通过目标定位、路线生成、碰撞检测、路线调整等步骤,规划移动机器人行动路线,通过控制量的计算,实现视觉伺服控制功能。系统测试结果表明,所设计控制系统的位置控制误差较小,姿态角和移动速度控制误差仅为0.05°和0.12m/s,移动机器人碰撞次数较少,具有较好的移动机器人视觉伺服控制效果,能够有效提高移动机器人视觉伺服控制精度。