Η παρούσα διπλωματική εργασία ασχολείται με την κατασκευή ενός εικονικού περιβάλλοντος που αναπαριστά μια σχολική τάξη. Στην εικονική τάξη προστίθενται εικονικοί χαρακτήρες που αποτελούν τους μαθητές της τάξης καθώς επίσης και τη δασκάλα τους. Το σενάριο που ακολουθεί είναι η ενημέρωση των εικονικών μαθητών από τη διδάσκουσα για τους τρόπους αντίδρασης των μαθητών σε περίπτωση σεισμού. / -

Fixed-base driving simulators are commonplace in research and training. Simulators provide safe and controlled environments to train users on vehicle and device operation, to evaluate the safety of devices and controls, and to conduct research on driving and driving behaviours. One drawback to simulators is simulator sickness. As with motion sickness, simulator sickness can cause nausea, but additionally it has symptoms such as headache and eyestrain. Simulator sickness is a problem for multiple reasons: it can skew experimental results, it can waste participants’ and experimenter’s time, and it can limit testable populations. In addition, participants may modify their behaviour to avoid sickness, affecting experimental results or impeding learning. While sickness can reduce over multiple exposures, it is not known if any observable behaviours accompany these reductions. It is also not known why there are such marked individual differences in susceptibility. To test for behaviours that could be responsible for reducing sickness, I examined participants across two sessions in a fixed-base driving simulator. I found that gaze behaviour (eye and head movements) changed along with sickness. To determine the cause for this finding I instructed participants (pre-drive) to fixate their gaze during the curves of a simulated drive. This gaze modification was effective in reducing sickness during a first-time experience in the simulator, supporting a causal link. Next, I attempted to replace the missing vestibular input in a fixed-base simulator, so that the visual and vestibular perceptions of motion matched. This experiment showed that by providing vestibular stimulation appropriate or opposite of what would occur in the real world reduced sickness. This provided support for the theory that distracting stimulation (electrical in this case) could reduce attention to visual motion cues and therefore reduce conflict, a novel finding for simulator sickness research. Finally, I tested for any correlations between individual differences and sickness. I found that history of motion sickness and current illness both correlated with sickness, potentially useful as a pre-screening tool. In addition, driving behaviours such as speed, braking, and acceleration all correlated with sickness, showing that how a person behaves in a simulation could also contribute to sickness. / CFI, OGS, Auto21

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Computer-aided fixture planning (CAFP) is an essential part of Computer-aided design and manufacturing (CAD/CAM) integration. Proper fixture planning can dramatically reduce the manufacturing cost, the lead-time, and labor skill requirements in product manufacturing. However, fixture planning is a highly experience-based activity. Due to the extreme diversity and complexity of manufacturing workpieces and processes, there are not many fixture planning tools available for industry applications. Moreover, existing CAFP methods rarely consider integrating fixture environmental factors into fixture planning. Automatic fixture planning using VR can provide a viable way for industries. This thesis develops automated approaches to fixture planning in a virtual environment (VE). It intends to address two important issues: automatic algorithms for fixture planning, and the VE to support high fidelity evaluation of fixture planning. The system consists of three parts including fixture assembly planning, feasibility analysis of assembly tools, and motion planning for fixture loading and unloading. The virtual fixture planning system provides the fixture designer a tool for fixture planning and evaluation. Geometrical algorithms are developed to facilitate the automatic reasoning. A Web-based VE for fixture planning is implemented. The three-dimensional (3D) model visualization enables the fixture simulation and validation effectively to investigate existing problems. Approaches to construct desktop-based large VEs are also investigated. Cell segmentation methods and dynamic loading strategies are investigated to improve the rendering performance. Case studies of virtual building navigation and product assembly simulations are conducted. The developed algorithms can successfully generate the assembly plan, validate the assembly tools, and generate moving paths for fixture design and applications. The VE is intuitive and sufficient to support fixture planning, as well as other virtual design and manufacturing tasks.

In this thesis, we propose a new design of privacy and session control for improving a collaborative molecular modeling CVR system AMMP-VIS [1]. The design mainly addresses the issue of competing user interests and privacy protection coordination. Based on our investigation of AMMP-VIS, we propose a four-level access control structure for collaborative sessions and dynamic action priority specification for manipulations on shared molecular models. Our design allows a single user to participate in multiple simultaneous sessions. Moreover, a messaging system with text chatting and system broadcasting functionality is included. A 2D user interface [2] for easy command invocation is developed in Python. Two other key aspects of system implementation, the collaboration Central deployment and the 2D GUI for control are also discussed. Finally, we describe our system evaluation plan which is based on an improved cognitive walkthrough and heuristic evaluation as well as statistical usage data.

Computer-aided fixture planning (CAFP) is an essential part of Computer-aided design and manufacturing (CAD/CAM) integration. Proper fixture planning can dramatically reduce the manufacturing cost, the lead-time, and labor skill requirements in product manufacturing. However, fixture planning is a highly experience-based activity. Due to the extreme diversity and complexity of manufacturing workpieces and processes, there are not many fixture planning tools available for industry applications. Moreover, existing CAFP methods rarely consider integrating fixture environmental factors into fixture planning. Automatic fixture planning using VR can provide a viable way for industries. This thesis develops automated approaches to fixture planning in a virtual environment (VE). It intends to address two important issues: automatic algorithms for fixture planning, and the VE to support high fidelity evaluation of fixture planning. The system consists of three parts including fixture assembly planning, feasibility analysis of assembly tools, and motion planning for fixture loading and unloading. The virtual fixture planning system provides the fixture designer a tool for fixture planning and evaluation. Geometrical algorithms are developed to facilitate the automatic reasoning. A Web-based VE for fixture planning is implemented. The three-dimensional (3D) model visualization enables the fixture simulation and validation effectively to investigate existing problems. Approaches to construct desktop-based large VEs are also investigated. Cell segmentation methods and dynamic loading strategies are investigated to improve the rendering performance. Case studies of virtual building navigation and product assembly simulations are conducted. The developed algorithms can successfully generate the assembly plan, validate the assembly tools, and generate moving paths for fixture design and applications. The VE is intuitive and sufficient to support fixture planning, as well as other virtual design and manufacturing tasks.

The research program described in this dissertation updates the knowledge base concerning human navigation and presents new methods for investigating selection and use of cognitive navigational strategies. Four experiments were designed to answer questions about the effects of environmental and experiential factors on cognitive mapping and selection of navigation strategies. Humans are thought to navigate using two different reference frames often referred to as “world based” and “person based”. These reference frames correspond to two probable cognitive/memory systems respectively labelled “allocentric” for the formation and use of cognitive maps of the environment, and “egocentric” for navigation by stimulus response or guidance. Different navigational strategies are associated with the two systems. Allocentric strategies rely on the presence of a stable environmental structure containing a number of more distal, relational stimuli whereas egocentric strategies rely only on the presence of simple, local cues (cue-based egocentric) or on body movements (response-based egocentric). The experiments tested navigation behaviour and strategy selection using virtual environment analogues of an animal model, the Morris water maze. Adaptations included, 1) the Place maze biasing participants toward the use of an allocentric strategy, 2) the Cue maze (and Floor Cue maze) biasing participants toward the use of an egocentric strategy, and 3) the Dual-strategy maze that has no bias because participants can choose to utilize either an allocentric or egocentric strategy. Experiment 1 was a behavioural study testing 101 university students in the Place maze and Floor Cue maze, with and without the opportunity to explore the environment before testing. The experiment showed for the first time that exploration is necessary for allocentric but not for egocentric navigation, suggesting that prior exploration is important for cognitive mapping. Experiment 2 outlined a novel and reliable eye tracking method for differentiating strategy use in the Place and Cue mazes. Eye movements were measured during the first orientation second of behavioural trials to differentiate allocentric from egocentric strategy use. Experiment 3 employed the established eye tracking method to test the effects of experience on strategy selection. Participants were trained in either the Place maze or the Cue maze and then tested in the Dual-strategy maze. A strategy probe trial was introduced at the end of testing to indicate whether participants had selected an allocentric or an egocentric strategy. Training experience had a strong behavioural effect on later strategy selection at the end of testing. Furthermore the effect of experience occurred independently of the gender of participants. However, the experience effect was only briefly shown using eye tracking measures. Experiment 4 was a successful feasibility study showing that eye tracking measures can be utilized to measure navigational strategy use in survivors of traumatic brain injury. Together these experiments may indicate that strategies are not innate or within the person but rather are interactions of the person with the environment. / Graduate

Several researchers have successfully developed realistic models of real world objects/ phenomena and then have simulated them in the virtual world. In this thesis, we propose the opposite: instantiating virtual world events in the real world. The interactive 3D virtual environment provides a useful, realistic 3D world that resembles objects/phenomena of a real world, but it has limited capability to communicate with the physical environment. We argue that new and intuitive 3D user interfaces, such as 3D virtual environment interfaces, may provide an alternative form of media for communicating with the real environment. We propose a 3D virtual world-based add-on architecture that achieves a synchronized virtual-real communication. In this framework, we explored the possibilities of integrating haptic and real world object interactions with Linden Lab's multiuser online 3D virtual world, Second Life. We enhanced the open source Second Life viewer client in order to facilitate communications between the real and virtual world. Moreover, we analyzed the suitability of such an approach in terms of user perception, intuition and other common parameters. Our experiments suggest that the proposed approach not only demonstrates a more intuitive mode of communication system, but also is appealing and useful to the user. Some of the potential applications of the proposed approach include remote child-care, communication between distant lovers, stress recovery, and home automation.

ABSTRACT PRESENTATION OF CLASSICAL ARCHAEOLOGICAL SITES IN VIRTUAL ENVIRONMENT CASE STUDY: SAGALASSOS BASAgA&Ccedil / , &Ouml / zge M.S, Department of Architecture in Restoration Supervisor: Dr. Fuat G&Ouml / K&Ccedil / E July 2005, 123 pages Parallel to the growing concern for the protection and presentation of archaeological sites, virtual environments (VE) are in use for visualization purposes since mid 1980&rsquo / s. This thesis investigates the potentials and problems of presenting a classical archaeological site in VE from the viewpoint of conservation science, to ensure the welfare of the remains. The study is handled in two sections as a conceptual part and a case study. The conceptual part, first dwells upon the history, aim and techniques of the VE presentations. This section ends with the development of criteria for the evaluation of VE presentations of classical archaeological sites. For the case study, the antique city of Sagalassos is investigated through its history, urban tissue, architecture, multidisciplinary studies and VE projects. The thesis concludes with general remarks on the presentation of classical archaeological sites in VE and proposes some solutions to improve the presentation of Sagalassos in particular.

近年來3D虛擬環境與語音界面(Voice User Interface)在個人電腦上的應用逐漸受到重視。說話是人類最自然的溝通方式，若能在虛擬環境中加入語音界面，將使人物間的互動更為流暢。近年來雖有許多研究致力於3D虛擬環境與語音界面的整合，但在多人環境中對話管理(Dialog Management)等相關問題上，一直缺乏有效的解決方案。本研究的主要目的，即在解決語音界面整合及對話管理等問題，並實現多人虛擬環境的語音互動機制。我們針對虛擬環境中語音與動畫同步、對話管理機制與多人環境中之語音處理機制等問題，設計一個以VoiceXML為基礎的XAML-V (eXtensible Animation Markup Language – Voice extension ) 語言，並將其實作結果於一個多人虛擬環境系統中驗証其可行性及有效性。 / The applications of 3D virtual environments and voice user interface (VUI) on personal computers have received significant attentions in recent years. Since speech is the most natural way of communication, incorporating VUI into virtual environments can enhance user interaction and immersiveness. Although there have been many researches addressing the issue of integrating VUI and 3D virtual environment, most of the proposed solutions do not provide an effective mechanism for multi-user dialog management. The objective of this research is on providing a solution for VUI integration and dialog management and realizing such a mechanism in a multi-user virtual environment. We have designed a dialog scripting language called XAML-V (eXtensible Animation Markup Language – Voice Extension), based on the VoiceXML standard, to address the issues of synchronization between VUI and animation and dialog management for multi-user interaction. We have also implemented such a language and realized it on a multi-user virtual environment to evaluate the effectiveness of this design.