Towards high-fidelity multi-sensory virtual environments

Virtual environments are playing an increasingly important role for training people about real world situations, especially through the use of serious games. A key concern is thus the level of realism that virtual environments require in order to have an accurate match of what the user can expect in the real world with what they perceive in the virtual one. Failure to achieve the right level of realism runs the real risk that the user may adopt a different reaction strategy in the virtual world than would be desired in reality. High-fidelity, physically-based rendering has the potential to deliver the same perceptual quality of an image as if you were “there” in the real world scene being portrayed. However, our perception of an environment is not only what we see, but may be significantly influenced by other sensory inputs, including sound, smell, feel, and even taste. Computation and delivery of all sensory stimuli at interactive rates is a computationally complex problem. To achieve true physical accuracy for each of the senses individually for any complex scene in real-time is simply beyond the ability of current standard desktop computers. This paper discusses how human perception, and in particular any cross-modal effects in multi-sensory perception, can be exploited to selectively deliver high-fidelity virtual environments. Selective delivery enables those parts of a scene which the user is attending to, to be computed in high quality. The remainder of the scene is delivered in lower quality, at a significantly reduced computational cost, without the user being aware of this quality difference.     

Locales: supporting large multiuser virtual environments

Creators of multiuser virtual environments naturally desire to make them large in spatial extent, large in numbers of objects, and large in numbers of users interacting with the environment. However, doing so creates several problems: efficiently managing the flow of large amounts of data between large numbers of users, representing precise position and velocity information about objects arrayed across a large volume of space, and allowing designers to create parts of a virtual environment separately and combine them together later. The concept of locales is based on the idea that even in a very large virtual world, most of what a single user can observe at a given moment is nevertheless local in nature. You would expect a large virtual world to be large primarily because, like a city, it combines a large number of relatively small, localized activities not because it contains very large individual activities. Locales divide a virtual world into chunks that can be processed separately. This division is purely an implementation issue-it is not apparent to the user. A user sees several locales at once-generally the locale containing the user's point of view and those neighboring it. The user does not see any seams between the locales nor any abrupt changes as the point of view moves from one locale to another, thereby changing the neighborhood set     

Embedded DHT overlays in virtual computing environments

With the rapid development of computing and networking technologies, people propose to build harmonious, trusted and transparent Internet-based virtual computing environments (iVCE). The overlay-based organization of dynamic Internet resources is an important approach for iVCE to realizing efficient resource sharing. DHT-based overlays are scalable, low-latency and highly available; however, the current DHT overlay (SKY) in iVCE cannot satisfy the trust requirements of Internet applications. To address this...     

Towards an immortal operating system in virtual environments

Many OS crashes are caused by bugs in kernel extensions or device drivers while the OS itself may have been tested rigorously. To make an OS immortal we must resurrect the OS from these crashes. We present a novel OS-hypervisor infrastructure that allows automated and transparent OS crash diagnosis and recovery in a virtual environment. This infrastructure eliminates the need for reboots or checkpoint-restart mechanisms, which require preserving the states of critical applications before the crash happens and also require extensive modifications to those applications. At the core of our approach is a small hidden OS-repair-image that is dynamically created from the healthy running OS instance. When an OS crashes, the hypervisor dynamically loads this repair-image to perform diagnosis and repair. One way of repair we have experimented with, is to quarantine the offending process and resume the running of the fixed OS automatically without a reboot. Experimental evaluations demonstrated that it takes less than 3 s to recover from an OS crash. This approach can significantly reduce the downtime and maintenance costs in data centers, and is the first design and implementation of an OS-hypervisor combo capable of automatically resurrecting a crashed commercial server-OS. In addition to online diagnosis and recovery, this infrastructure can also be used for offline diagnosis and can be incorporated into the technical support tools of the OS vendor. Additionally, we have used parts of this infrastructure to speed-up the diagnosis of AIX OS-crashes for the IBM technical support teams.     

Prototyping and analysing ubiquitous computing environments using multiple layers

If ubiquitous computing (ubicomp) is to enhance physical environments then early and accurate assessment of alternative solutions will be necessary to avoid costly deployment of systems that fail to meet requirements. This paper presents APEX, a prototyping framework that combines a 3D Application Server with a behaviour modeling tool. The contribution of this framework is that it allows exhaustive analysis of the behaviour models that drive the prototype while at the same time enabling immersive exploration of a virtual environment simulating the proposed system. The development of prototypes is supported through three layers: a simulation layer (using OpenSimulator); a modelling layer (using CPN Tools) and a physical layer (using external devices and real users). APEX allows movement between these layers to analyse different features, from user experience to user behaviour. The multi layer approach makes it possible to express user behaviour in the modelling layer, provides a way to reduce the number of real users needed by adding simulated avatars, and supports user testing of hybrids of virtual and real components as well as exhaustive analysis. This paper demonstrates the approach by means of an example, placing particular emphasis on the simulation of virtual environments, low cost prototyping and the formal analysis capabilities.     

A software infrastructure for supporting spontaneous and personalized interaction in home computing environments

Our daily lives are expected to change dramatically due to the popularity of ubiquitous computing technologies. These will make it possible to integrate various aspects of our lives. However, a new approach is required to seamlessly deal with devices embedded in our environments. Future embedded systems will embody a new approach that will take into account a variety of new issues, for example, spontaneous interaction, personalization, privacy protection, and interoperability. In this paper, we propose a personal home server that will make it possible to coordinate home appliances. Since everyone will have a different personal home server, it will allow us to personalize how the appliances are used according to individual preferences. Our personal home server can seamlessly discover and configure appliances at any locations, such as at railroad stations, cars, and streets as well as houses. We also discuss its design and implementation and present its current status.     

Trustworthy self-optimization for organic computing environments using multiple simultaneous requests

Open distributed systems are rapidly getting more and more complex. Therefore, it is essential that such systems will be able to adapt autonomously to changes in their environment. They should be characterized by so-called self-x properties such as self-configuration, self-optimization and self-healing. The autonomous optimization of nodes at runtime in open distributed environments is a crucial part for developing self-optimizing systems. In this paper, we present a self-optimization approach that does not only consider pure load-balancing but also takes into account trust to improve the assignment of important services to trustworthy nodes. Our approach uses different optimization strategies to determine whether a service should be transferred to another node or not. The evaluation results showed that the proposed approach is able to balance the workload between nodes nearly optimal. Moreover, it improves significantly the availability of important services, i.e., the achieved availability was no lower than 85% of the maximum theoretical availability value.     

Towards user centred design (UCD) in architecture based on immersive virtual environments

This paper describes a generic concept of how to combine the experience of user centred design (UCD) in the field of Human Computer Interaction (HCI) with the traditional approach of participatory design (PD) in an architectural design process. Even if some basic requirements of this generic method are not available yet, this paper will also describe an approach, which enables planners even now to involve end users by using virtual environments (VE) as immersive and spatial prototype. It will be described and illustrated by the way of example using the building project Centre of Virtual Engineering of the Fraunhofer Institute for Industrial Engineering (IAO) in Stuttgart. It demonstrates that the transfer of the UCD approach to architectural planning combined with the provision of an adequate prototype can make a significant contribution towards an increase in quality and performance in building and construction projects.     

Navigation in desktop virtual environments: an evaluation and recommendations for supporting usability

Virtual reality (VR) can provide useful tools for a variety of applications. However, for these tools to be effective, they must be easy to use. In virtual environments (VEs), usability is impaired by poorly designed navigation systems. Insufficient realism and missing physiological orientation and motion cues impair spatial learning in desktop VEs. Capabilities for navigation in a VE are far more varied than in reality; so much greater flexibility can be offered, but designing VEs with too many options can overwhelm users. To assist designers in building effective, usable navigation systems for VEs, navigation techniques must be evaluated to identify which features actually support users in accomplishing their tasks and which features create unnecessary problems.This study evaluates navigation in two different VEs to develop recommendations for the design of navigation systems in desktop VEs. The study consists of an objective assessment of navigation control dynamics, a guideline-based evaluation and a review of data collected during two experimental studies. The findings indicate that real-world constraints, specialised navigation techniques and feedback regarding location and direction of travel are needed to support navigation in desktop VEs.     

Towards perceptual fidelity: Slant perception in real and interactive virtual environments

An innovative motoric measure of slant based on gait is proposed as the angle between the foot and the walking surface during walking. This work investigates whether the proposed action-based measure is affected by factors such as material and inclination of the walking surface. Experimental studies were conducted in a real environment set-up and in its virtual simulation counterpart evaluating behavioural fidelity and user performance in ecologically-valid simulations. In the real environment, the measure slightly overestimated the inclined path whereas in the virtual environment it slightly underestimated the inclined path. The results imply that the proposed slant measure is modulated by motoric caution. Since the “reality” of the synthetic environment was relatively high, performance results should have revealed the same degree of caution as in the real world, however, that was not the case. People become more cautious when the ground plane was steep, slippery, or virtual.     

A computational model of perceptual saliency for 3D objects in virtual environments

When giving directions to the location of an object, people typically use other attractive objects as reference, that is, reference objects. With the aim to select proper reference objects, useful for locating a target object within a virtual environment (VE), a computational model to identify perceptual saliency is presented. Based on the object’s features with the major stimulus for the human visual system, three basic features of a 3D object (i.e., color, size, and shape) are individually evaluated and then combined to get a degree of saliency for each 3D object in a virtual scenario. An experiment was conducted to evaluate the extent to which the proposed measure of saliency matches with the people’s subjective perception of saliency; the results showed a good performance of this computational model.     

Resource management framework for collaborative computing systems over multiple virtual machines

A resource management framework for collaborative computing systems over multiple virtual machines (CCSMVM) is presented to increase the performance of computing systems by improving the resource utilization, which has constructed a scalable computing environment for resource on-demand utilization. We design a resource management framework based on the advantages of some components in grid computing platform, virtualized platform and cloud computing platform to reduce computing systems overheads and maintain workloads balancing with the supporting of virtual appliance, Xen API, applications virtualization and so on. The content of collaborate computing, the basis of virtualized resource management and some key technologies including resource planning, resource allocation, resource adjustment and resource release and collaborative computing scheduling are designed in detail. A prototype is designed, and some experiments have verified the correctness and feasibility of our prototype. System evaluations show that the time in resource allocation and resource release is proportional to the quantity of virtual machines, but not the time in the virtual machines migrations. CCSMVM has higher CPU utilization and better performance than other systems, such as Eucalyptus 2.0, Globus4.0, et al. It is concluded that CCSMVM can accelerate the execution of systems by improving average CPU utilization from the results of comparative analysis with other systems, so it is better than others. Our study on resource management framework has some significance to the optimization of the performance in virtual computing systems.     

Automatic camera control in virtual environments augmented using multiple sparse videos

Automated virtual camera control has been widely used in animation and interactive virtual environments. We have developed a multiple sparse camera based free view video system prototype that allows users to control the position and orientation of a virtual camera, enabling the observation of a real scene in three dimensions (3D) from any desired viewpoint. Automatic camera control can be activated to follow selected objects by the user. Our method combines a simple geometric model of the scene composed of planes (virtual environment), augmented with visual information from the cameras and pre-computed tracking information of moving targets to generate novel perspective corrected 3D views of the virtual camera and moving objects. To achieve real-time rendering performance, view-dependent textured mapped billboards are used to render the moving objects at their correct locations and foreground masks are used to remove the moving objects from the projected video streams. The current prototype runs on a PC with a common graphics card and can generate virtual 2D views from three cameras of resolution 768×576 with several moving objects at about 11 fps.     

The use of ‘exploratory learning’ for supporting immersive learning in virtual environments

User interfaces are becoming more intuitive following the requirements of the individual learner and reinforcing the drive towards more personalised learning and greater learner autonomy. There are clearly a new set of challenges emerging for teaching practitioners that will have implications upon not just what is learned but importantly upon lesson planning. This paper explores these changes to teaching through a consideration of an exploratory learning model which allows practitioners to rethink how they teach in 3D and immersive spaces where learning sequences and experiences are choreographed to support peer interactions and exchanges. The ELM extends from Kolb’s experiential learning model to adapt the use of 3D applications, and provides examples from research and development projects to exemplify how the model works in practice. Teaching in these contexts provides less emphasis upon curriculum and more emphasis upon sequencing learning experiences, meta-reflection, peer assessment and group work.     

Towards the Scheduling of Multiple Workflows on Computational Grids

The workflow paradigm has become the standard to represent processes and their execution flows. With the evolution of e-Science, workflows are becoming larger and more computational demanding. Such e-Science necessities match with what computational Grids have to offer. Grids are shared distributed platforms which will eventually receive multiple requisitions to execute workflows. With this, there is a demand for a scheduler which deals with multiple workflows in the same set of resources, thus the development of multiple workflow scheduling algorithms is necessary. In this paper we describe four different initial strategies for scheduling multiple workflows on Grids and evaluate them in terms of schedule length and fairness. We present results for the initial schedule and for the makespan after the execution with external load. From the results we conclude that interleaving the workflows on the Grid leads to good average makespan and provides fairness when multiple workflows share the same set of resources.     

Adapting grid computing environments dependable with virtual machines: design, implementation, and evaluations

Due to its potential, using virtual machines in grid computing is attracting increasing attention. Most of the researches focus on how to create or destroy a virtual execution environments for different kinds of applications, while the policy of managing the virtual environments is not widely discussed. This paper proposes the design, implementation, and evaluation of an adaptive and dependable virtual execution environment for grid computing, ADVE, which focuses on the policy of managing virtual machines in grid environments. To build a dependable virtual execution environments for grid applications, ADVE provides an set of adaptive policies managing virtual machine, such as when to create and destroy a new virtual execution environment, when to migrate applications from one virtual execution environment to a new virtual execution environment. We conduct experiments over a cluster to evaluate the performance of ADVE, and the experimental results show that ADVE can improve the throughput and the reliability of grid resources with the adaptive management of virtual machines.     

Large scale distributed visualization on computational Grids: A review

Advances in science and engineering have put high demands on tools for high performance large-scale data exploration and analysis. Visualization is a powerful technology for analyzing data and presenting results. Todays science and engineering have benefited from state-of-the-art of Grid technologies and modern visualization systems. To visualize the large amount of data, rendering technologies are widely used to parallelize visualization tasks over distributed resources on computational Grids. It raises the necessity to balance the computational load and to minimize the network bandwidth requirements. This article explains in Grid environments how new approaches of visualization architecture and load-balancing algorithms address these challenges in a principled fashion. The Grid infrastructure that supports large scale distributed visualization is also introduced. Some typical visualization systems on Grids are referenced for discussions.