Augmented reality agents for user interface adaptation

Most augmented reality (AR) applications are primarily concerned with letting a user browse a 3D virtual world registered with the real world. More advanced AR interfaces let the user interact with the mixed environment, but the virtual part is typically rather finite and deterministic. In contrast, autonomous behavior is often desirable in ubiquitous computing (Ubicomp), which requires the computers embedded into the environment to adapt to context and situation without explicit user intervention. We present an AR framework that is enhanced by typical Ubicomp features by dynamically and proactively exploiting previously unknown applications and hardware devices, and adapting the appearance of the user interface to persistently stored and accumulated user preferences. Our framework explores proactive computing, multi‐user interface adaptation, and user interface migration. We employ mobile and autonomous agents embodied by real and virtual objects as an interface and interaction metaphor, where agent bodies are able to opportunistically migrate between multiple AR applications and computing platforms to best match the needs of the current application context. We present two pilot applications to illustrate design concepts. Copyright © 2007 John Wiley & Sons, Ltd.     

Learning from virtual reality applications in education

This paper presents an overview of the uses of virtual reality in education. It draws particularly on three projects, the West Denton High School in Newcastle, the Human-Computer Interface Technology Laboratory's summer school in Seattle and the Shepard School for children with special needs in Nottingham. In each of these projects, there is distinctive relationship between the learning experience and the experience of virtual worlds. Here, the concern will not be with the pedagogical value of these projects, which have been documented elsewhere, but with the wider contribution that they can make to our understanding of virtual environments. To do this, it examines in each case how the virtual reality systems are integrated into the curriculum, how these systems relate to the learning process, the usability of the systems, and the possibilities and constraints of the virtual worlds. By comparing these with other emerging virtual reality applications, such as entertainment games, it can be seen that different systems present a variety of possibilities for constructing presence in, and interaction with, virtual environments.     

Softnet——一个基于移动代理的主动网络

在服务质量单一的互连网上为不同的服务提供一个可选择的平台,已是目前运行开发产所面临的最大的难题,无论是物理隔离的SDH通道、智能光网络和互连网中的虚拟网络,目的都是为不同的用户提供不同的服务平台。该文提出了一种基于移动代理的主动网络－－Softnet.Softnet是叠加在IP网上、中间节点可编程的虚拟网络。Softnet采用包含代码和数据的主动包,以主动节点上动态驻留的移动代理实现网络的动态服务,通过虚电路连接移动代理实现可编程虚拟网。Softnet为不同的服务提供可选择的虚拟平台,达到综合服务（VoIP、数据等服务）的目的。Softnet在提高协议效率,加速协议、服务的开发和部署,高效利用网络资源等方面都有较好的潜力。该文以实例说明了Softnet的动态性和可编程性。     

Space‐time planning in changing environments : using dynamic objects for accessibility

Navigation is a critical task for agents populating virtual worlds. In the last years, numerous solutions have been proposed to solve the path planning problem in order to enhance the autonomy of virtual agents. Those solutions mainly focused on static environments, eventually populated with dynamic obstacles. However, dynamic objects are usually more than just obstacles as they can be used by an agent to reach new locations. In this paper, we propose an online path planning algorithm in dynamically changing environments with unknown evolution such as physically based‐environments. Our method represents objects in terms of obstacles but also in terms of navigable surfaces. This representation allows our algorithm to find temporal paths through disconnected and moving platforms. We will also show that the proposed method also enables several kinds of adaptations such as avoiding moving obstacles or adapting the agent postures to environmental constraints. Copyright © 2012 John Wiley & Sons, Ltd.     

A Flexible Architecture for Virtual Humans in Networked Collaborative Virtual Environments

Complex virtual human representation provides more natural interaction and communication among participants in networked virtual environments, hence it is expected to increase the sense of being together within the same virtual world. We present a flexible framework for the integration of virtual humans in networked collaborative virtual environments. A modular architecture allows flexible representation and control of the virtual humans, whether they are controlled by a physical user using all sorts of tracking and other devices, or by an intelligent control program turning them into autonomous actors. The modularity of the system allows for fairly easy extensions and integration with new techniques making it interesting also as a testbed for various domains from “classic” VR to psychological experiments. We present results in terms of functionalities, example applications and measurements of performance and network traffic with an increasing number of participants in the simulation.     

Modeling Methods for Reusable and Interoperable Virtual Entities in Multimedia Virtual Worlds

Virtual Worlds are facing several challenges to become a mature technology commonly used in their numerous potential applications such as games, training, education, health and collaborative work. Main challenges are the introduction of multimedia in virtual worlds and the decrease of the cost and the required time for their design, which remains an empirical process. This paper proposes a methodology for introducing multimedia and decreasing the cost and needed time. The main interest of the proposed methodology is to provide virtual worlds with multimedia, interoperability and reusability properties. Interoperability enables virtual entities belonging to virtual worlds independently designed (i.e., no prior explicit agreement exists between theirs respective designers) to interact with each others. Reusability enables virtual worlds designers to use a virtual entity pattern initially designed for a virtual world A to be used in the design of a new virtual world B. The originality of this methodology relies on multiagent concepts and learning techniques for avoiding prior complex specifications tasks to achieve interoperability and reusability of multimedia virtual entities in virtual worlds.     

To Plan or to Simply React? An Experimental Study of Action Planning in a Game Environment

Many contemporary computer games, notably action and role‐playing games, represent an interesting class of navigation‐intensive dynamic real‐time simulations inhabited by autonomous intelligent virtual agents (IVAs). Although higher level reasoning of IVAs in these domains seems suited for action planning, planning is not widely adopted in existing games and similar applications. Moreover, statistically rigorous study measuring performance of planners in decision making in a game‐like domain is missing. Here, five classical planners were connected to the virtual environment of Unreal Development Kit along with a planner for delete‐free domains (only positive preconditions and positive effects). Performance of IVAs employing those planners and IVAs with reactive architecture was measured on a class of game‐inspired test environments of various sizes and under different levels of external interference. The analysis has shown that planning agents outperform reactive agents if (i) the size of the problem is small or if (b) the environment changes are either hostile to the agent or infrequent. In delete‐free domains, specialized approaches are inferior to classical planners because the lower expressivity of delete‐free domains results in lower plan quality. These results can help to determine when planning is advantageous in games and for IVAs control in other dynamic real‐time environments.     

The changing nature of user attitudes toward virtual world technology: A longitudinal study

Virtual world technologies have been utilized in gaming for a number of years but only recently have they been applied as a serious tool for business. Many business applications have been identified, including the use of virtual worlds for team collaboration, training, and education, but a question remains about whether users will accept the premise that virtual worlds represent useful environments for engaging in business functions. We address this question by examining user reactions to virtual worlds. The first study looks at attitudes of users of the virtual world Second Life during three time periods (i.e., before exposure to the environment, after an information session and discussion of Second Life, and after use of the environment). Two variables, user acceptance of virtual world technologies and user self-efficacy, were examined as the primary dependent measures. Results show that while self-efficacy increases over time, user acceptance decreases in a highly correlated pattern. A second study investigates the underlying causes of the observed pattern of user acceptance using a content analysis of written reflections of user experiences. Both studies paint a detailed picture of user intentions and some of the reasons these intentions developed after use. The paper concludes with a discussion of the implications of these results for business managers and researchers.     

Visual creation of inhabited 3D environments

The creation of virtual reality applications and 3D environments is a complex task that requires good programming skills and expertise in computer graphics and many other disciplines. The complexity increases when we want to include complex entities such as virtual characters and animate them. In this paper we present a system that assists in the tasks of setting up a 3D scene and configuring several parameters affecting the behavior of virtual entities like objects and autonomous virtual humans. Our application is based on a visual programming paradigm, supported by a semantic representation, an ontology for virtual environments. The ontology allows us to store and organize the components of a 3D scene, together with the knowledge associated with them. It is also used to expose functionalities in the given 3D engine. Based on a formal representation of its components, the proposed architecture provides a scalable VR system. Using this system, non-experts can set up interactive scenarios with minimum effort; no programming skills or advanced knowledge is required.     

Behaviourally rich actions for user-controlled characters

The increasing use of animated characters and avatars in computer games and 3D online worlds requires increasingly complex behaviour with increasingly simple and easy to use control systems. This paper presents a system for user-controlled actions that aims at simplicity and ease of use while being enhanced by modern animation techniques to produce rich and complex behaviour. We use inverse kinematics based motion adaptation to make pre-existing pieces of motion apply to new targets. The expressiveness of the character is enhanced by adding autonomous behaviour, in this case eye gaze behaviour. This behaviour is generated autonomously but is still influenced by the actions that the user is requesting the character to perform. The actions themselves are simple for a designer with no programming experience to design and for an end user to customise. They are also very simple to invoke.     

Predicting users' return to virtual worlds: a social perspective

Virtual worlds or three‐dimensional computer‐based simulated environments have received considerable attention as platforms for entertainment, education and commerce. In contrast to a web site, for example, where a user interacts with a two‐dimensional site, virtual worlds provide a platform in which users can interact with other individuals, sometimes including strangers, within three‐dimensional environments. Virtual worlds afford a form of ‘socialness’ unlike many other technologies, often motivating a user – by virtue of these social experiences – to return. Drawing on the Spatial Model of Interaction and Awareness‐Attention Theory, we demonstrate that besides social aspects, which include social awareness and social perception, flow experience, which is the mental state of being fully absorbed and somewhat lost in time, is an essential ingredient in an individual's decision to return to a virtual world. We also demonstrate how characteristics of the technology are linked to the social aspects experienced in virtual worlds. A laboratory study conducted in a virtual world, Second Life, supports our assertions and identifies state predictors of flow that influence individuals' intentions to return to the virtual world environment.     

Interconnecting distributed virtual worlds using Metabots: performance evaluation against the traditional client‐server model

Virtual Worlds evolution is breaking the barriers of virtual isolation, thus allowing users to participate in geographically dispersed and culturally diverse places. At the same time, mobile agents have been established as a solid programming method for heterogeneous networking and computing environments. Our work focuses on the definition of a distributed Virtual World reference platform for enhanced users' experience. Towards interconnecting virtual worlds with mobile agents, we have further enriched the concept of a human‐like appearance avatar. We propose two distributed virtual world architectures, namely loose and tight. In parallel, we present a relevant implementation scheme along with experimental results that prove the performance enhancements achieved against the classic client/server model. Copyright © 2014 John Wiley & Sons, Ltd.     

Modelling virtual cities dedicated to behavioural animation

In order to populate virtual cities, it is necessary to specify the behaviour of dynamic entities such as pedestrians or car drivers. Since a complete mental model based on vision and image processing cannot be constructed in real time using purely geometrical information, higher levels of information are needed in a model of the virtual environment. For example, the autonomous actors of a virtual world would exploit the knowledge of the environment topology to navigate through it. In this article, we present a model of virtual urban environments using structures and information suitable for behavioural animations. Thanks to this knowledge, autonomous virtual actors can behave like pedestrians or car drivers in a complex city environment. A city modeler has been designed, using this model of urban environment, and enables complex urban environments for behavioural animation to be automatically produced.     

Fuzzy cognitive maps for the simulation of individual adaptive behaviors

This paper focuses on the simulation of behavior for autonomous entities in virtual environments. The behavior of these entities must determine their responses not only to external stimuli, but also with regard to internal states. We propose to describe such behavior using fuzzy cognitive maps (FCMs), whereby these internal states might be explicitly represented. This paper presents the use of FCMs as a tool to specify and control the behavior of individual agents. First, we describe how FCMs can be used to model behavior. We then present a learning algorithm allowing the adaptation of FCMs through observation. Copyright © 2010 John Wiley & Sons, Ltd.     

Harmonic rendering for visual coherence on mobile outdoor AR environment

Rapid developments in augmented reality (AR) and related technologies have led to increasing interest in immersive content. AR environments are created by combining virtual 3D models with a real-world video background. It is important to merge these two worlds seamlessly if users are to enjoy AR applications, but, all too often, the illumination and shading of virtual objects is not consider the real world lighting condition or does not match that of nearby real objects. In addition, visual artifacts produced when blending real and virtual objects further limit realism. In this paper, we propose a harmonic rendering technique that minimizes the visual discrepancy between the real and virtual environments to maintain visual coherence in outdoor AR. To do this, we introduce a method of estimating and approximating the Sun’s position and the sunlight direction to estimate the real sunlight intensity, as this is the most significant illumination source in outdoor AR and it provides a more realistic lighting environment for such content, reducing the mismatch between real and virtual objects.