Thesis (M.A.)--University of Toronto, 2004. / Adviser: Jim Hewitt.

Thesis (Ed. D.)--University of Toronto, 2005. / Includes bibliographical references (leaves 205-214).

Thesis (Ed. D.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains xi, 129 p. : ill. Includes abstract. Includes bibliographical references (p. 97-105).

This thesis investigates the development of a low cost, component based facial virtual conferencing system. The design is decomposed into an encoding phase and a decoding phase, which communicate with each other via a network connection. The encoding phase is composed of three components: model acquisition (which handles avatar generation), pose estimation and expression analysis. Audio is not considered part of the encoding and decoding process, and as such is not evaluated. The model acquisition component is implemented using a visual hull reconstruction algorithm that is able to reconstruct real-world objects using only sets of images of the object as input. The object to be reconstructed is assumed to lie in a bounding volume of voxels. The reconstruction process involves the following stages: - Space carving for basic shape extraction; - Isosurface extraction to remove voxels not part of the surface of the reconstruction; - Mesh connection to generate a closed, connected polyhedral mesh; - Texture generation. Texturing is achieved by Gouraud shading the reconstruction with a vertex colour map; - Mesh decimation to simplify the object. The original algorithm has complexity O(n), but suffers from an inability to reconstruct concave surfaces that do not form part of the visual hull of the object. A novel extension to this algorithm based on Normalised Cross Correlation (NCC) is proposed to overcome this problem. An extension to speed up traditional NCC evaluations is proposed which reduces the NCC search space from a 2D search problem down to a single evaluation. Pose estimation and expression analysis are performed by tracking six fiducial points on the face of a subject. A tracking algorithm is developed that uses Normalised Cross Correlation to facilitate robust tracking that is invariant to changing lighting conditions, rotations and scaling. Pose estimation involves the recovery of the head position and orientation through the tracking of the triangle formed by the subject's eyebrows and nose tip. A rule-based evaluation of points that are tracked around the subject's mouth forms the basis of the expression analysis. A user assisted feedback loop and caching mechanism is used to overcome tracking errors due to fast motion or occlusions. The NCC tracker is shown to achieve a tracking performance of 10 fps when tracking the six fiducial points. The decoding phase is divided into 3 tasks, namely: avatar movement, expression generation and expression management. Avatar movement is implemented using the base VR system. Expression generation is facilitated using a Vertex Interpolation Deformation method. A weighting system is proposed for expression management. Its function is to gradually transform from one expression to the next. The use of the vertex interpolation method allows real-time deformations of the avatar representation, achieving 16 fps when applied to a model consisting of 7500 vertices. An Expression Parameter Lookup Table (EPLT) facilitates an independent mapping between the two phases. It defines a list of generic expressions that are known to the system and associates an Expression ID with each one. For each generic expression, it relates the expression analysis rules for any subject with the expression generation parameters for any avatar model. The result is that facial expression replication between any subject and avatar combination can be performed by transferring only the Expression ID from the encoder application to the decoder application. The ideas developed in the thesis are demonstrated in an implementation using the CoRgi Virtual Reality system. It is shown that the virtual-conferencing application based on this design requires only a bandwidth of 2 Kbps. / Adobe Acrobat Pro 9.4.6 / Adobe Acrobat 9.46 Paper Capture Plug-in

This dissertation investigated the effects of group size, group member proximity and the interaction of these two variables on the performance of brainstorming groups in a synchronous, computer-mediated environment. A laboratory experiment was employed to manipulate the independent variables group size (4- and 8-member) group member proximity. Group member proximity was manipulated by allowing proximate groups to work in a single meeting room, while members of distributed group worked in separate rooms. The subjects, upper-level, undergraduate business students, were asked to identify and discuss all "people, groups and organizations" that would be affected by a proposed policy to require all undergraduate business students to have individual access to a personal computer. The computer-mediated brainstorming system allowed all group members to enter and share information simultaneously, as all communication was electronic. Group performance was assessed by counting the total number of unique solutions generated and by the sum of expert rated quality scores for each unique solution. Groups in all conditions contributed approximately the same number of comments and felt equally satisfied. Contrary to an ample body of noncomputer-mediated brainstorming research, large groups were more productive than small groups for both idea quantity and quality. Small groups were, however, more productive than large groups on a per person basis, as increased group size yielded diminishing returns. Remote groups were more productive than proximate groups. Group researchers have found that group interaction produces productivity gains and losses, each of which increase in strength as the group size increases. This research found group productivity losses for computer-mediated brainstorming to be relatively constant, as the technology mitigated productivity inhibitors in conditions where prior noncomputer-mediated research has found these losses to increase (i.e., larger groups).

Fu, Zhengjia. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (p. 64-70 ). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iv / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Design for group network communication --- p.6 / Chapter 2.1 --- Performance metrics of network Voice Conference: GMOS --- p.7 / Chapter 2.2 --- Conference Leader Selection strategies --- p.11 / Chapter 2.3 --- Experiment Description --- p.14 / Chapter 2.4 --- Data analysis and results --- p.16 / Chapter 2.5 --- Applications of Proposals to Voice Conference --- p.25 / Chapter 3 --- P2P Application Identification --- p.27 / Chapter 3.1 --- Periodic Group Communication Patterns --- p.28 / Chapter 3.1.1 --- Terminology for Behavioral Patterns --- p.29 / Chapter 3.1.2 --- Pattern 1: Gossip of Buffer Maps --- p.30 / Chapter 3.1.3 --- Pattern 2: Content flow control --- p.31 / Chapter 3.1.4 --- Pattern 3: Synchronized Link Activation and Deactivation --- p.32 / Chapter 3.2 --- Identification Based on behavioral signatures --- p.33 / Chapter 3.2.1 --- Algorithm Overview --- p.34 / Chapter 3.2.2 --- Sequence Generation (SG1): Time Series for the Gossip Pattern --- p.36 / Chapter 3.2.3 --- Transform Time-domain Sequence to Frequency-domain Sequence --- p.36 / Chapter 3.2.4 --- Sequence Generation (SG2): Time Series for Content Flow Control Pattern --- p.40 / Chapter 3.2.5 --- Sequence Generation (SG3): Time Series for Synchronized Start and Finish of Flows --- p.41 / Chapter 3.2.6 --- Analyzer step --- p.47 / Chapter 3.3 --- Behavioral signatures of popular P2P applications --- p.47 / Chapter 3.4 --- Experiment Results --- p.49 / Chapter 3.5 --- Discussion --- p.52 / Chapter 4 --- Related Work --- p.58 / Chapter 5 --- Conclusion --- p.62 / Bibliography --- p.64

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI/Dissertation Abstracts International.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 135-142). Available also in a digital version from Dissertation Abstracts.

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Despite the growth in the size and acceptance of distance education, there have been persistent criticisms of this form of education because it often fails to provide for interaction among students and between students and instructors. Without this, it is suggested, distance education can only be an inferior imitation of the best face-to-face education because learners are unable to clarify and challenge assumptions and to construct meaning through dialogue. Some critics believe distance education's inability to reproduce a critical dialogue among students and between students and instructor can be addressed through the use of two-way communication technologies such as text-based, asynchronous (i.e., not in real time) computer conferencing. Appropriately-designed computer conferencing, it is argued, will facilitate interaction among students and between the instructor and students thus making distance education more appropriate for the higher-level cognitive goals of college and university education. At the same time, using this' technology will retain the flexibility of time and place-independence that is characteristic of distance education. The literature on educational computer conferencing is replete with references to its potential to create a new paradigm of education characterized by interactive group knowledge-building and critical thinking, but there are few empirical studies that have substantiated this view. Little is known about how and why learners participate and what factors may affect their participation. Similarly there has been little empirical study of the quality of computer conferencing interaction. This case study of a university-level course delivered by computer conferencing was designed to address these issues. It was guided by two purposes: 1) to determine whether the quantitative and qualitative dimensions of participation in this online course were consistent with key aspects of the new paradigm of networked learning as articulated in the literature, that is, if students were actively participating, building on each others contributions and thinking critically about the discussion topics; and 2) to determine what factors affected student participation and critical thinking. The results of this study suggest that some of the claims about the potential of this technology to transform conventional and distance education may be overstated. The emergence of a dynamic and interactive educational process that facilitates critical thinking was shown to be contingent on a variety of factors. The results suggest, however, that with the appropriate course design, instructor interventions, content, and students, computer conferencing can be used for these purposes and should be given serious consideration by distance educators as a way of facilitating interaction and critical thinking in distance education.