Channeling the data flood

The distributed virtual environment (DVE) can provide a simulated environment in which two or more participants interact with each other and with their surroundings. In working with this software, users face great technological problems, of which the biggest are: managing the enormous data loads involved; negotiating the interplay of all the virtual objects, including the virtual people; and creating the most efficient network topologies possible for users' machines. At the network level, each occupant of a DVE system uses a computer that is connected to a local- or wide-area network (LAN or WAN), which provides information on the changing state of the virtual environment and its contents. The paper discusses the design of a distributed virtual environment and the use of the Internet     

虚拟现实中的人机自然交互技术

虚拟现实技术是当前计算机技术领域发展的新方向，其指利用计算机技术、传感与测量技术、仿真技术和微电子技术等手段构建的一个模拟虚拟世界的技术类型。通过该技术，用户可以接受和响应模拟环境的各种感官刺激，从而与对应环境中的人或物进行交互，并产生身临其境的感受。若想使虚拟现实技术达到上述目标，则需重点关注相应的人机交互技术。文中从当前虚拟现实技术的概念及特征入手，对虚拟现实中的人机自然交互技术进行了探讨。     

Human Factors Evaluation Techniques to Aid Understanding of Virtual Interfaces

Advances in enabling technologies such as broadband wide area networks and the proliferation of the Internet has led to industry and home users looking beyond conventional communications media. Consequently, the telecommunications industry has been extending its application domain over recent years. Indeed, mediated communication has become a reasonably well established research area. Numerous modes of communication have been utilised successfully for various applications. From e-mail and text chat to videoconferencing systems, the use of mediated communication has become a part of daily life. Virtual environments (VEs) are highly configurable media, ranging from relatively basic to extremely elaborate architectures. At their most complex, they promise a seamless interface between real and synthesised environments. The potential for media-rich environments is seeded in the technology's capacity to faithfully represent the participants (both physically and dynamically) and for those participants to present and interact with (shared) data in an intuitive manner. It is the latter of these attributes which is highly relevant to communications and is discussed in this paper. The various configurations of virtual reality (VR) technology make matching the user to the technology an extremely complex task. Clearly, a basis for evaluating the effectiveness of these systems is required. Even though human factors (HF) evaluation and design techniques are well established in other human/computer interaction (HCI) fields, knowledge and understanding of virtual interfaces is limited. HF evaluation in VR is a complex subject and covers many aspects, such as basic human performance, cognition, and sensory capability. To address all these factors individually in an empirical fashion would demand a very long and expensive research programme. In addition, such studies may not predict the user's overall performance in a multi-modal VE. This paper deals with an alternative approach to understanding the issues of human performance in virtual environments via a process of top-down systems engineering evaluation. This paper is designed to provide an introduction to the assessment of virtual environments, and a reference for interface designers and researchers engaged in the investigation of mediated communication.     

Computer Vision for a 3-D Visualisation and Telepresence Collaborative Working Environment

An integrated media system is a computer-based environment that supports the creation, sharing, distribution and effective communication of multimodal information across the boundaries of space and time. The EU Information Societies Technology (IST) project — VIRTUE (Virtual Team User Environment) is working steadily towards the realisation of most aspects and properties of such a system, with particular emphasis on a three-way semi-immersive telepresence videoconferencing scenario. In contrast with the traditional videoconferencing system that we know now, the outcome of the project is expected to demonstrate distinctive presence features and experience for the conference participants. These include views of full-body-size realistically rendered images, eye-to-eye contact, gaze awareness, normal hand gesturing and direct body language. The purpose of this paper is to describe the current work in its related technical field, and the main objectives and scope of this project. One optional software system framework is outlined, and also illustrated are some component technologies in 3-D computer vision analysis that are being developed. The application of these component technologies, notably the dense-disparity estimation and the novel view synthesis, in 3-D interactive video manipulation and visualisation, are widely expected.     

Latency-driven distribution: infrastructure needs of participatory entertainment applications

This article evaluates network and server infrastructure requirements to support real-time flows associated with networked entertainment applications. These include the state information flow to update the status of the virtual environment and immersive communication flows such as voice, video, gesture, and haptics communication. The article demonstrates that scaling these applications to large geographical spreads of participants requires distribution of computation to meet the latency constraints of the applications. This latency-driven distribution of computation is essential even when there are no limitations on the availability of computational resources in one location. The article provides detailed results on distributed server architectures for two of these real-time flows, state information and immersive voice communication. It also identifies a generic set of requirements for the underlying network and server infrastructure to support these applications and propose a new design, called switched overlay networks, for this purpose.     

Optimal diversity allocation in multiuser communication systems. I.System model

A class of multiuser multicarrier communication systems is introduced to study the influence of resource allocation on the performance of multiuser communication systems operating over fading channels. This class of systems includes both systems that employ exclusive allocation schemes, where users are allotted time-bandwidth slots without interference from other users, and systems that employ shared allocation schemes, where users are allotted time-bandwidth slots that are also employed by other users. The optimal weighting factors used in the combining of the received signals from the slots of a single user for the conventional receiver is derived, and the performance of systems in the class is characterized. For each of a number of popular multiuser architectures, it is shown that there exists a system in the class with nearly identical performance. Based on these relations, it is concluded that a class of systems has been introduced that allows the study of the merits of different types of time-bandwidth allocation under a single framework     

宽带CDMA通信的主动式多用户动态检测方法

本文针对适合未来大用户量、多媒体移动通信的宽带CDMA系统,提出了一种根据不同业务需求及综合多址无线通信环境的动态QoS要求,进行主动式多用户信号检测的方法.通过对接收系统多用户检测器的动态配置,以满足不同误码率(BER)及系统稳健性的要求,获得最佳的系统和网络效率.     

True-view Videoconferencing System Through 3-D Impression of Telepresence

It can be argued that an ideal teleconferencing system would offer a sense of presence comparable to that afforded by real face-to-face meetings. In contrast, traditional desktop videoconferencing loses essential socially important phenomena such as true perspective views, live facial expressions and tacit body language. This paper reports a prototype concept demonstrator under development at BT Laboratores that addresses these issues in order to make the use of videoconferencing a normal social activity rather than a means of merely getting messages across the channel. The idea is to place participants from different remote sites in a coherent virtual environment naturally extended from the real world. The participants have correct views of each other and the illusion of close proximity. The rationale is to build on the demonstrator and enhance it with increasingly realistic functional components as the relevant technical solutions become available. Results are presented of a stereo-based vision system which can synthesise novel (or virtual camera) perspective views of the scene from two fixed camera views. The technique is currently capable of providing 'look-around' views and a certain degree of navigation capability around the scene. Research issues are discussed together with the practical difficulties that remain to be solved in implementing a true-view, telepresence, videoconferencing system.     

Interactive collaborative media environments

Virtual reality (VR) provides a revolutionary interface between man and machine. However, present display and interface peripherals limit the potential of virtual environments within many activities or scenarios. Mainstream immersive VR is centred on head mounted display (HMD) based solutions in which the user is isolated from their surrounding environment. The occlusion of real world interaction within such systems imposes unnatural social and physical constraints on the user. Media environments can be classified as one form of enhanced reality based around immersive physical spaces intensified for effective collaborative activities. Current research is directed at three forms of enhanced spaces — immersive projected displays, interactive video environments, and immersive desktop environments. While HMD and desktop VR facilitates many collaborative tasks, the synthesis of real and virtual realities within a life-size environment offers distinct advantages within other applications. This paper introduces the concepts behind media environments, reviews current research and presents applications being explored at BT Laboratories.     

Three-dimensional Internet developments

This paper describes the application of Internet-based three-dimensional (3-D) user interfaces, comparing them with more traditional two-dimensional (2-D) interfaces. The modelling of 3-D worlds in the Virtual Reality Modelling Language (VRML) is described, together with an overview of VRML and its likely future direction. Multi-user shared environments, which enable Internet users to meet and communicate with each other in cyberspace via avatars (3-D representations of users), are then introduced. A shared information garden is described which allows people to meet and share information in a dynamic, information-rich, virtual environment.     

e-collaboration: the reality of virtuality

With the development of new technologies, and particularly information and communication technologies (ICTs), teams have evolved to encompass new forms of interaction and collaboration. By focusing on the communicative dimensions of global virtual teams, this paper demonstrates that e-collaboration is more than a technological substitution for traditional face-to face collaboration. It places special emphasis on the importance of structuring activities for balancing electronic communication during e-collaboration (i.e., videoconference, email, chat session, distributed use of group support system) to bridge cultural and stereotypical gaps, to increase profitable role repartition between the participants, and to prevent and solve conflicts. During the past four years, the authors have developed a project involving hundreds of participants from different national cultures working together for six weeks on a specific project. In this paper, we present our experiences and draw conclusions, giving special attention to the structure of the electronic communication required to support efficient virtual teaming in education and industry.     

JOINT SPACE－FREQUENCY MULTIUSER SYMBOL DETECTOR FOR MC－CDMA SYSTEM WITH UNIFORM LINEAR ARRAY

The MultiCarrier COde Division Multiple Access (MC-CDMA) scheme is promising for relieving capacity limit problems of Direct Sequence(DS-CDMA systems due to serious InterCip Interference(ICI) and MultiUser Interference(MUI)in high-data-rate wireless communication systems.In this paper the Uniform Linear Array(ULA) is applied to the base station of macrocellular MC-CDMA systems in a frequency-selective fading channel environment.A joint space-frequency multiuser symblo sequence detector is developed for all active users within one macrocell without space-frequency channel estimation.Simultaneously,Directions-of -Arrivals (ODAs)of all active users can also be estimated.By dividing the ULA into two identical overlapping subarrays,a specific auxiliary matrix is constructed,which includes both symbol sequence and DOA information of all active users,Then,based on the subspace method,performing the eigen decomposition on such auxiliary matrix,the closed-form solution of symbol sequences and DOAs for all active users can be obtained.In comparison with schemes based on channel estimation,our algorithm need not explicitly estimate the space-frequency channel for each active user,so it has lower computation complexity,Extensive computer simulations demonstrate the overall performance of this novel scheme.     

Channel Models for Medical Implant Communication

Information regarding the propagation media is typically gathered by conducting physical experiments, measuring and processing the corresponding data to obtain channel characteristics. When this propagation media is human body, for example in case of medical implants, then this approach might not be practical. In this paper, an immersive visualization environment is presented, which is used as a scientific instrument that gives us the ability to observe RF propagation from medical implants inside a human body. This virtual environment allows for more natural interaction between experts with different backgrounds, such as engineering and medical sciences. Here, we show how this platform has been used to determine channel models for medical implant communication systems.     

Developing a 2.5-D video avatar

Immersive projection technology has become very popular as a virtual reality display system. A 2.5-D video avatar method was proposed and developed. The 2.5-D video avatar was created using a depth map generated by a stereo camera, and it was superimposed on the shared virtual world in real time. A 2.5-D video avatar was also transmitted between two immersive projection displays, computer augmented booth for image navigation (CABIN) and COSMOS, which were connected by a high bandwidth ATM network. In addition, we experimentally evaluated the accuracy of pointing when using the 2.5-D video avatar     

Effect of Interaction Based on Augmented Context in Immersive Virtual Reality Environment

Virtual reality has recently rapidly emerged into the global spotlight. With the current increasing interest in head mounted display (HMD) as the next-generation content platform to replace smartphones, many companies are endeavoring to gain an early foothold in the virtual reality market. In HMD-based virtual reality environments, users are completely isolated from the real world, and are thus unable to perform even simple and familiar interactions with the real world. This paper proposes interaction based on context information augmented with stories, visuals, and sounds, as opposed to an interface that replicates the existing real world, in order to enable easy and natural interactions by users in HMD-based immersive virtual reality environments. The results of a user study conducted using our proposed augmented context-based interactions in an immersive virtual reality environment verify that it provides users with higher levels of immersion, accuracy, and emotional empathy than a virtual reality environment that simply replicates the existing real world.     

Virtual offices

A concept for a new business communication environment consisting of a shared and interactive multiuser virtual space that consists of a computer-graphics-based virtual space and video-based objects is proposed. This combination results in an extremely flexible environment for remote human collaboration. The human interface, which entails walking and interacting within the virtual space and offers a new dimension in daily communication activities, is described     

Interference robustness aspects of space-time block code-based transmit diversity

Transmit diversity, which was initially developed for noise-limited environments, has been promoted as a viable candidate for improving the link quality in both existing and future systems for wireless communication. However, to ensure efficient spectrum utilization, receivers operating within wireless multiuser networks must be robust not only to fading and noise but to interference from other system users as well. This work considers interference robustness aspects when transmit diversity, in the form of space-time block coding, is used in multiuser systems. Properties of the space-time block encoded signals such as code rate, block structure, diversity order, etc., and their implications on detection and interference rejection by means of noise whitening are discussed. To handle the presence of space-time block encoded interference, a space-time processing-based extension of an interference rejection combining algorithm is proposed. Results are presented indicating that transmit diversity based on space-time block codes (STBCs) of the linear dispersion type improve robustness against interference in terms of an increased diversity advantage. This can be achieved either by increasing the number of transmit antennas or by reducing the rate of the code. It is also shown, by analysis and by simulation examples, that the performance improvements obtained by using transmit diversity in multiuser systems may rapidly subside as the signal-to-interference ratio decreases. However, by using the proposed interference rejection scheme tailored to the space-time encoded structure, performance improvements of transmit diversity are also obtained in a multiuser environment.     

Face analysis and synthesis

The author's goal is to generate a virtual space close to the real communication environment between network users or between humans and machines. There should be an avatar in cyberspace that projects the features of each user with a realistic texture-mapped face to generate facial expression and action controlled by a multimodal input signal. Users can also get a view in cyberspace through the avatar's eyes, so they can communicate with each other by gaze crossing. The face fitting tool from multi-view camera images is introduced to make a realistic three-dimensional (3-D) face model with texture and geometry very close to the original. This fitting tool is a GUI-based system using easy mouse operation to pick up each feature point on a face contour and the face parts, which can enable easy construction of a 3-D personal face model. When an avatar is speaking, the voice signal is essential in determining the mouth shape feature. Therefore, a real-time mouth shape control mechanism is proposed by using a neural network to convert speech parameters to lip shape parameters. This neural network can realize an interpolation between specific mouth shapes given as learning data. The emotional factor can sometimes be captured by speech parameters. This media conversion mechanism is described. For dynamic modeling of facial expression, a muscle structure constraint is introduced for making a facial expression naturally with few parameters. We also tried to obtain muscle parameters automatically from a local motion vector on the face calculated by the optical flow in a video sequence     

PERFORMANCE OF MULTIUSER DETECTION FOR CDMA SYSTEM IN A FLAT RAYLEIGH FADING ENVIRONMENT

In a CDMA communication network using conventional signal detection, system capacity is limited and its performance is degraded by the multi-access interference (MAI). Multiuser detection, which makes use of cross-correlation information between spread spectrum codes, can reduce or eliminate the MAI in a Gaussian channel so as to mitigate the near-far effects and increase the system capacity. This paper extends the multiuser detector to a flat Rayleigh fading CDMA environment, and discusses the bit error rate of typical multiuser detection algorithms in such a environment by combining theoretical analysis and computer simulation. It is shown that multiuser detection is superior to conventional detections in the flat Rayleigh fading channels.     

Using a serious game to communicate risk and minimize psychological distance regarding environmental pollution

Persuading individuals to engage in pro-environmental behavior is challenging. Interactive media, such as virtual environments and video games, present opportunities to minimize psychological distance and bolster perceived risks associated with environmental threats. In this experiment, we tested the effects of a serious game that allowed users to engage in environmental cleanup. In the virtual environment, participants (N = 190) navigated down a polluted river that was described as geographically and temporally close or distant. The affordance of interactivity, specifically contingency, was also manipulated. Results revealed that feeling psychologically close to the environment led to greater risk perception, which in turn led to more environmental behavior and greater support for environmental policy in the days following the experiment. In terms of interactivity, higher perceptions of contingency led to greater self-efficacy, which also led to more environmental behavior and greater support for environmental policy after the experiment. We discuss implications for environmental communication, science communication, and other prosocial persuasion efforts using interactive media such as serious games and virtual reality.