Unenforced E-commerce transactions

Electronic commerce currently relies on traditional third party enforcement mechanisms that don't necessarily translate well to cyberspace. Chunking algorithms offer one possibility for unenforced transactions between self motivated agents. This method enables transactions in settings where the parties cannot identify each other, or where litigation is not viable. It also allows computational agents to be more autonomous by not requiring them to be strictly tied to the real world parties they represent. In cases where this type of unenforced exchange is possible, it is preferable to the strictly enforced mode of exchange because it saves enforcement costs (for example, litigation costs or operations costs of trusted third party intermediaries) and it is insensitive to enforcement uncertainties. The method is based on managing the exchange between two agents-a supplier and a demander-so that the gains from completing the exchange (cooperating according to a contract) at any point are larger for both agents than the gains from terminating it (defecting the exchange prematurely by vanishing)     

Conditioned suppression in a virtual environment

Virtual environments (VEs) provide an inexpensive way of conducting ecologically valid psychological research. The present study used a VE to demonstrate conditioned suppression, a behavioral model of anxiety, in a first-person perspective video game. During operant training, participants learned to shoot crates to find gold bars and thus score points in the game. Next, during Pavlovian conditioning, a colored light (i.e., conditioned stimulus: CS+) was followed by a white noise unconditioned stimulus (US) while a different colored light (CS−) was not paired with the US. Probe trials in a final testing phase were then used to assess suppression. We found significant suppression of accurate responding (shots hitting the designated targets) during the presence of the CS+ relative to the CS−, both in terms of total hits and hits as a proportion of total shots. Importantly, this effect emerged despite the overall level of operant responding being undiminished during the CS+. Our findings are consistent with related studies examining human behavior in real environments, and demonstrate the potential of VEs in combination with a modestly aversive CS to allow a detailed behavioral profile of anxiety to emerge.     

Controlling a camera in a virtual environment

image-based control or visual servoing approach. It consists of positioning a camera according to the information perceived in the image. This is thus a very intuitive approach of animation. To be able to react automatically to modifications of the environment, we also considered the introduction of constraints into the control. This approach is thus adapted to highly reactive contexts (virtual reality, video games). Numerous examples dealing with classic problems in animation are considered within this framework and presented in this paper. Published online: 19 July 2001     

The Responsive Workbench: a virtual work environment

In this virtual environment, customized scientific visualization tools offer specialists new ways to work cooperatively, which opens the door to more comprehensive analysis and, perhaps, reduced costs. Implementing the Responsive Workbench required close attention to several important elements: its components, a typical setup, the user interface, feedback speed and real-time rendering     

CyberWalk: a web-based distributed virtual walkthrough environment

A distributed virtual walkthrough environment allows users connected to the geometry server to walk through a specific place of interest, without having to travel physically. This place of interest may be a virtual museum, virtual library or virtual university. There are two basic approaches to distribute the virtual environment from the geometry server to the clients, complete replication and on-demand transmission. Although the on-demand transmission approach saves waiting time and optimizes network usage, many technical issues need to be addressed in order for the system to be interactive. CyberWalk is a web-based distributed virtual walkthrough system developed based on the on-demand transmission approach. It achieves the necessary performance with a multiresolution caching mechanism. First, it reduces the model transmission and rendering times by employing a progressive multiresolution modeling technique. Second, it reduces the Internet response time by providing a caching and prefetching mechanism. Third, it allows a client to continue to operate, at least partially, when the Internet is disconnected. The caching mechanism of CyberWalk tries to maintain at least a minimum resolution of the object models in order to provide at least a coarse view of the objects to the viewer. All these features allow CyberWalk to provide sufficient interactivity to the user for virtual walkthrough over the Internet environment. In this paper, we demonstrate the design and implementation of CyberWalk. We investigate the effectiveness of the multiresolution caching mechanism of CyberWalk in supporting virtual walkthrough applications in the Internet environment through numerous experiments, both on the simulation system and on the prototype system.     

Solid modelling in a virtual reality environment

This paper presents a constraint-based methodology for intuitive and precise solid modelling in a virtual reality (VR) environment. A hierarchically structured and constraint-based data model is developed to support solid modelling in the VR environment. A constraint reasoning engine is also developed to automatically deduce allowable motions for precise constraint-based 3D manipulations. A prototype system of product modelling has been successfully developed, and experimental results demonstrate the advantage of precise solid modelling through constraint-based manipulation in virtual environments.     

Analyzing engineering simulations in a virtual environment

We present new results of ongoing research in developing a virtual environment for car-body engineering applications. Creating VRML scenes lets us use the Internet as a communication platform     

Sensory-motor enhancement in a virtual therapeutic environment

The sensory-motor skills of persons with neuromuscular disabilities have been shown to be enhanced by intensive and repetitive therapeutic interventions. This paper describes a form of low immersion virtual reality and a prototype, open source system that allow a user with significant physical disability to actively interact with computer-generated objects whose behaviors promote a game-like interaction. Unlike fully immersive and haptic virtual reality, this approach frees the user from head-mounted displays and gloves. It extracts the user’s real-time silhouette from the output of a remote video camera and uses that two-dimensional outline to interact with graphical objects on screen. In contrast to video games that have been modified with specialized interfaces, this virtual interaction system promotes the repetitive use of goal directed movements of the arms and body, which are essential to promote cortical reorganization, as well as discourage unwanted changes in muscle tissue that result in contracture. A prototype system demonstrates the potential of low immersion technology to motivate users and encourage participation in therapy. It also offers the potential of accommodating the sensory-motor skills of individuals with very significant impairment. The behaviors of the computer-generated graphics can be altered to allow use by those with very limited range of motion and/or motor control. These behaviors can be adjusted to provide a continuing challenge as the user’s skills improve. This prototype is described in terms of functional capabilities that include a silhouette extraction from a video image, and generation of graphical objects that interact with the silhouette. The work is extended with a discussion of a more sophisticated region of interest detection algorithm that can select specific parts of the body.     

Quadruped virtual robot simulation in a virtual environment obeying physical laws

In the development of a robot, the validation of that robot with the use of real machinery takes a considerable amount of time and money. In particular, it is difficult to validate a robot’s behavior in an unsafe place. The developers also have to pay attention to virtual debugging. Using a program validated in VR space makes the verification of a real machine’s behavior more efficient. In this research, we make a virtual robot walk on a road autonomously by using a program where the virtual robot tracks a line in a virtual environment.     

VRMosaic: Web access from within a virtual environment

For the foreseeable future, users of virtual reality systems will likely spend more time in the “real” environment than in a virtual environment. In the “real” environment, users access much of their data using flat screen applications, which include tools such as authoring and analysis programs and even hyperlinked browsers. We believe that users will find VEs more appealing if they can import their flat screen applications. We also believe that the World Wide Web infrastructure, and supporting tools such as NCSA Mosaic, Netscape's Navigator, and Sun's HotJava, have become a de facto standard both for making data available and allowing limited interaction with that data. These beliefs motivated us to develop a technology for porting flat screen applications based on the 3.1 version of the InterViews toolkit into VR. NCSA Mosaic provided us with a real application that would: (1) test our infrastructure effectively; and (2) provide a compelling application example. We used our “2D interface in VR” infrastructure to port Mosaic into RealEyes, our VR system. Dubbed “VRMosaic”, this application lets users familiar with Mosaic access the Web from within an immersive VE. But VRMosaic is not just an embedded version of NCSA Mosaic-it also allows for VR specific features such as navigation within the VE     

Measuring virtual experience in a three-dimensional virtual reality interactive simulator environment: a structural equation modeling approach

With the rapid development of the VR market, virtual experience has increasingly been the object of study in recent years. A growing number of studies have reported the positive effect that virtual experience can have on a user’s mood and loyalty. However, few studies have investigated the influence of the mechanism of virtual experience on users’ mood and loyalty. To compensate for this research gap, this study aims to evaluate consumers’ virtual experience by examining the flow state in a virtual environment. A total of 368 valid questionnaires were collected, and a structural equation modeling approach was employed in the data analysis. The study reveals that forming flow involves many factors: the intrinsic characteristics of the mediated environment, the consumer’s assumptions and perceptions prior to entering the flow state, the stage at which the customer enters the flow state, and the consequences of the flow experience.     

Real-time fluid simulation in a dynamic virtual environment

Simulating physically realistic complex fluid behaviors in a distributed interactive simulation (DIS) presents a challenging problem for computer graphics researchers. The authors consider how solving the 2D Navier-Stokes equations via a computational fluid dynamics method lets us map surfaces into 3D and achieves realistic real-time fluid surface behaviours     

A poetry performance in a collaborative virtual environment

The article presents the design of a poetry performance in a collaborative virtual environment (CVE) and discusses the experience of staging this performance to an audience of 200 members of the general public. The performance involved an extensive collaboration among computer scientists, poets, a graphic artist, and an event production team. The article explores a range of technical and production issues arising from this experience, including: developing rich and engaging forms of content for CVEs; exploring the tension between autonomy of action for audience members and the management of a performance to encourage appropriate behaviors at relevant times and places; considering spatial scoping techniques in enabling different modes of awareness and communication between participants as an event unfolds; developing appropriate embodiments for performers and audience; developing appropriate navigation interfaces for different participants who may or may not have experienced virtual reality (VR); exploring different ways of situating interfaces to a virtual environment within different physical environments based on notions of mixed reality; understanding the issues involved in designing and managing such an event and how these might influence construction tools for CVEs     

虚拟人环境感知的仿真方法研究

针对目标驱动的追击问题,将视线升维为柱体的视线筒,提出了一种虚拟人环境感知的筒视线方法.根据虚拟人所处的环境和行进速度,以变频方式、周期性地向目标发射筒视线,根据该筒视线与环境中障碍物的各碰撞点的信息和预先设置的行动推理知识库,确定虚拟人的追逐行动;为不完全可知的、动态虚拟环境中的目标追击问题提供了一种新的解决方案.该方案抛开了基于传统视野范围的拟人方式,以通过性的感知为中心,形成虚拟世界的互动性感知标准,建立虚拟人自身的感知功能,取得了更加逼真的仿真效果.原型系统验证了该方法的可行性和有效性.     

EVAC: a virtual environment for control of remote imaginginstrumentation

The objective of this project, called the Experimentalist's Virtual Acquisition Console (EVAC), was to demonstrate a prototype system for using virtual environments that would allow a researcher access the hardware in a remote experimental laboratory over high-speed networks, in order to control remote instrumentation. We wanted to give the researcher tools that would not only allow for complete control of the imaging system but also provide the potential for collaboration with researchers at distant sites. We targeted three imaging instruments, all located at the Beckman Institute for Advanced and Technology: a magnetic resonance imaging system, a transmission electron microscope and a scanning tunneling microscope. Our goal was not to control all three instruments simultaneously but rather to demonstrate that our unified virtual environment interface could be adapted to these widely different imaging devices. In building this demonstration, we faced many problems commonly encountered in developing a remote interface to a new instrument. These included the lack of any standard interface to the devices, the necessity of dealing with proprietary software, and the problem of developing a distributed model so that the instruments could be controlled over the network. The EVAC project has illustrated the potential of a virtual laboratory over a high-speed network     

VSculpt : a distributed virtual sculpting environment for collaborative design

A collaborative virtual sculpting system supports a team of geographically separated designers/engineers connected by networks to participate in designing three-dimensional (3D) virtual engineering tools or sculptures. It encourages international collaboration at a minimal cost. However, in order for the system to be useful, two factors need to be addressed: intuitiveness and real-time interaction. Although a lot of effort has been put into developing virtual sculpting environments, only limited work addresses collaborative virtual sculpting. This is because in order to support real-time collaborative virtual sculpting, many challenging issues need to be addressed. We propose a collaborative virtual sculpting framework, called VSculpt. Through adapting some techniques we developed earlier and integrating them with some techniques developed here, the proposed framework provides a real-time intuitive environment for collaborative design. In particular, it addresses issues on efficient rendering and transmission of deformable objects, intuitive object deformation using the CyberGlove and concurrent object deformation by multiple clients. We demonstrate and evaluate the performance of the proposed framework through a number of experiments.     

Way-finding during a fire emergency: an experimental study in a virtual environment

The way-finding behaviour and response during a fire emergency in a virtual environment (VE) was experimentally investigated. Forty participants, divided into two groups, were required to find the emergency exit as soon as possible in a virtual hotel building because of a fire escape demand under condition 1 (VE without virtual fire, control group) and condition 2 (VE with virtual fire, treatment group). Compared to the control group, the treatment group induced significantly higher skin conductivity and heart rate, experienced more stress, took longer time to notice the evacuation signs, had quicker visual search and had a longer escape time to find the exit. These results indicated that the treatment condition induced higher physiological and psychological stress, and had influenced the escape behaviour compared to the control group. In practice, fire evacuation education and fire evacuation system design should consider the response characteristics in a fire emergency.     

Learning effectiveness in a Web-based virtual learning environment: a learner control perspective

Web-based technology has a dramatic impact on learning and teaching. A framework that delineates the relationships between learner control and learning effectiveness is absent. This study aims to fill this void. Our work focuses on the effectiveness of a technology-mediated virtual learning environment (TVLE) in the context of basic information technology skills training. Grounded in the technology-mediated learning literature, this study presents a framework that addresses the relationship between the learner control and learning effectiveness, which contains four categories: learning achievement, self-efficacy, satisfaction, and learning climate. In order to compare the learning effectiveness under traditional classroom and TVLE, we conducted a field experiment. Data were collected from a junior high school of Taiwan. A total of 210 usable responses were analysed. We identified four results from this study. (1) Students in the TVLE environment achieve better learning performance than their counterparts in the traditional environment; (2) Students in the TVLE environment report higher levels of computer self-efficacy than their counterparts in the traditional environment; (3) Students in the TVLE environment report higher levels of satisfaction than students in the traditional environment; and (4) Students in the TVLE environment report higher levels of learning climate than their counterparts in the traditional environment. The implications of this study are discussed, and further research directions are proposed.     

Enabling a continuum of virtual environment experiences

We define a virtual environment as a set of surroundings that appear to a user through computer-generated sensory stimuli. The level of immersion-or sense of being in another world-that a user experiences within a VE relates to how much stimuli the computer delivers to the user. Thus, one can classify VEs along a virtuality continuum, which ranges from the real world to an entirely computer-generated environment. We present a technology that allows seamless transitions between levels of immersion in VEs. Milgram and Kishino (1994) first proposed the concept of a virtuality continuum in the context of visual displays. The concept of a virtuality continuum extends to multimodal VEs, which combine multiple sensory stimuli, including 3D sound and haptic capability, leading to a multidimensional virtuality continuum. Emerging applications will benefit from multiple levels of immersion, requiring innovative multimodal technologies and the ability to traverse the multidimensional virtuality continuum.