A telepresença, como um refinamento da teleoperação, permite que o indivíduo controle não apenas a simulação mas a própria realidade. Uma vez que, esta proporciona a habilidade de manipular a realidade física remotamente em tempo real, através de sua representação virtual. Através da tecnologia de realidade virtual, pode-se criar uma grande diversidade de ambientes apropriados aos mais variados tipos de aplicações, possibilitando simulações de situações do mundo real em um ambiente ou mundo virtual. A aplicação de ambientes virtuais no processo de manufatura está relacionada tanto com a manutenção e treinamento, como também a criação e simulação de protótipos virtuais antes de sua utilização no chão-de-fábrica. O uso de redes de Petri para modelagem de ambientes virtuais, mostra-se como uma poderosa ferramenta gráfica/matemática que pode capturar naturalmente as principais características dos sistemas de realidade virtual, além de proporcionar resultados empíricos interessantes na verificação automática de concorrência e sistemas de tempo real. Por permitir modelar a computação não determinística e paralela, a modelagem de ambientes virtuais com redes de Petri é adequada não apenas para simulação, verificação e validação desses sistemas, mas para o próprio controle dos ambientes modelados. Ao associar os elementos de uma rede de Petri com os elementos do paradigma orientado à objetos de um conjunto de classes que constituem os objetos que irão compor os ambientes virtuais e os sistemas de telepresença, obtém-se uma valiosa ferramenta para o controle dos métodos dos objetos virtuais e reais a serem invocados. O objetivo deste trabalho é o desenvolvimento do modo de associação de redes de Petri com objetos virtuais e reais para controle de ambientes virtuais imersivos e telepresença, com base na descrição de um sistema de autoria de telepresença com controle em RP. Os resultados obtidos trarão avanços quanto ao desenvolvimento e implantação de aplicações de manufatura virtual em um ambiente de visualização 3D imersivo. / The telepresence, as a refinement of teleoperation, allows the individual not only to control the simulation but also the own reality. Since this provides the ability to manipulate the physical reality remotely in real time, through its virtual representation. Through the technology of virtual reality, one can create a wide variety of environments suitable for all kinds of applications, enabling simulations of the situations in a real world environment or virtual world. The application of virtual environments in the manufacturing process is related to both the maintenance and training, and also the creation and simulation of virtual prototypes before their use in the shop-floor. The use of Petri nets for modeling virtual environments, shows itself as a powerful graphics/mathematics tool that can capture the main features of virtual reality systems, as well as offering interesting empirical results in automatic verification of concurrence and real time systems. By allowing to model non-deterministic and parallel computation, modeling of virtual environments with Petri nets is appropriate not only for simulation, verification and validation of these systems, but also for controlling the environments modeled. By associating the elements of a Petri net with the elements of the object oriented paradigm of a set of classes that are the objects that will compose the virtual environments and telepresence systems, one gets a valuable tool for controlling of the methods of virtual and real objects to be invoked. The objective of this work is the development of the mode of association of Petri nets with virtual and real objects for controlling immersive virtual environments and telepresence, based on the description of a telepresence authoring system controlled by PN. The results will bring progress on the development and deployment of virtual manufacturing applications in an immersive 3D visualization environment.

As the use of simulation increases across many diff erent application domains, the need for high- fidelity three-dimensional virtual representations of real-world environments has never been greater. This need has driven the research and development of both faster and easier methodologies for creating such representations. In this research, we present two diff erent inference-based geometric modeling techniques that support the automatic construction of complex cluttered environments. The fi rst method we present is a surface reconstruction-based approach that is capable of reconstructing solid models from a point cloud capture of a cluttered environment. Our algorithm is capable of identifying objects of interest amongst a cluttered scene, and reconstructing complete representations of these objects even in the presence of occluded surfaces. This approach incorporates a predictive modeling framework that uses a set of user provided models for prior knowledge, and applies this knowledge to the iterative identifi cation and construction process. Our approach uses a local to global construction process guided by rules for fi tting high quality surface patches obtained from these prior models. We demonstrate the application of this algorithm on several synthetic and real-world datasets containing heavy clutter and occlusion. The second method we present is a generative modeling-based approach that can construct a wide variety of diverse models based on user provided templates. This technique leverages an inference-based construction algorithm for developing solid models from these template objects. This algorithm samples and extracts surface patches from the input models, and develops a Petri net structure that is used by our algorithm for properly fitting these patches in a consistent fashion. Our approach uses this generated structure, along with a defi ned parameterization (either user-defi ned through a simple sketch-based interface or algorithmically de fined through various methods), to automatically construct objects of varying sizes and con figurations. These variations can include arbitrary articulation, and repetition and interchanging of parts sampled from the input models. Finally, we affim our motivation by showing an application of these two approaches. We demonstrate how the constructed environments can be easily used within a physically-based simulation, capable of supporting many diff erent application domains.

Deictic pointing—pointing at things during conversations—is natural and ubiquitous in human communication. Deictic pointing is important in the real world; it is also important in collaborative virtual environments (CVEs) because CVEs are 3D virtual environments that resemble the real world. CVEs connect people from different locations, allowing them to communicate and collaborate remotely. However, the interaction and communication capabilities of CVEs are not as good as those in the real world. In CVEs, people interact with each other using avatars (the visual representations of users). One problem of avatars is that they are not expressive enough when compare to what we can do in the real world. In particular, deictic pointing has many limitations and is not well supported. This dissertation focuses on improving the expressiveness of distant pointing—where referents are out of reach—in desktop CVEs. This is done by developing a framework that guides the design and development of pointing techniques; by identifying important aspects of distant pointing through observation of how people point at distant referents in the real world; by designing, implementing, and evaluating distant-pointing techniques; and by providing a set of guidelines for the design of distant pointing in desktop CVEs. The evaluations of distant-pointing techniques examine whether pointing without extra visual effects (natural pointing) has sufficient accuracy; whether people can control free arm movement (free pointing) along with other avatar actions; and whether free and natural pointing are useful and valuable in desktop CVEs. Overall, this research provides better support for deictic pointing in CVEs by improving the expressiveness of distant pointing. With better pointing support, gestural communication can be more effective and can ultimately enhance the primary function of CVEs—supporting distributed collaboration.

Thesis (M.A.)--Boise State University, 2009. / Includes bibliographical references (leaves 97-102).

'Virtual Environments' Breakout session from the Living the Future 8 Conference, April 23-24, 2012, University of Arizona Libraries, Tucson, AZ.

One of the fundamental aspects of a virtual environment is the virtual agents that inhabit them. In many applications, virtual agents are required to perceive input information from their environment and make decisions appropriate to their task based on their programmed reaction to those inputs. The research presented in this thesis focuses on the reactive behaviour of the agents. We propose a new control architecture to allow agents to behave autonomously in navigation tasks in unknown environments. Our behaviour-based architecture uses fuzzy logic to solve problems of agent control and action selection and which can coordinate conflicts among different operations of reactive behaviours. A Fuzzy Associative Memory (FAM) is used as the process of encoding and mapping the input fuzzy sets to the output fuzzy set and to optimise the fuzzy rules. Our action selection algorithm is based on the fuzzy α-level method with the Hurwicz criterion. The main objective of the thesis was to implement agent navigation from point to point by a coordination of planning, sensing and control. However, we believe that the reactive architecture emerging from this research is sufficiently general that it could be applied to many applications in widely differing domains where real-time decision making under uncertainty is required. To illustrate this generality, we show how the architecture is applied to a different domain. We chose the example of a computer game since it clearly demonstrates the attributes of our architecture: real-time action selection and handling uncertainty. Experimental results are presented for both implementations which show how the fuzzy method is applied, its generality and that it is robust enough to handle different uncertainties in different environments. In summary, the proposed reactive architecture is shown to solve aspects of behaviour control for autonomous virtual agents in virtual environments and can be applied to various application domains.

Thesis (Ph. D.)--University of Canterbury, 2008. / Typescript (photocopy). Includes bibliographical references (leaves 216-239). Also available via the World Wide Web.

Thesis (Ph.D)--Computing, Georgia Institute of Technology, 2009. / Committee Chair: MacIntyre, Blair; Committee Member: Bolter, Jay; Committee Member: Guzdial, Mark; Committee Member: Mateas, Michael; Committee Member: Mynatt, Elizabeth. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (M.A.)--Boise State University, 2009. / Title from t.p. of PDF file (viewed June 22, 2009). Includes bibliographical references (leaves 97-102).

Everyday face-to-face social interaction is increasingly being supplemented by computer- and video-mediated communication. With mediation, however, comes the potential loss of important non-verbal cues. It is therefore important to attempt to maintain the quality of the mediated interaction, such that it retains as many of the aspects of a real-world interaction as possible. Social presence is a measure of how similar a mediated interaction is to face-to-face, the most socially present situation, in terms of perceptions of and behaviour towards an interlocutor. Social presence can be mediated by many factors, one of which is mutual gaze, and social perceptions of an interlocutor are also thought to be related to task performance. For a successful interaction, therefore, an optimum amount of mutual gaze for maximising social presence and task performance is desirable. This research aims to investigate the relationship between mutual gaze, task performance and social presence, in order to discover the ideal conditions under which a successful mediated interaction can occur. Previous gaze research paradigms have involved one conversational partner staring continuously at the other, and the resulting mutual gaze being measured. It is hypothesised that this method may actually suppress mutual gaze, primarily due to social reasons. It is potentially, therefore, not the optimum experimental design for mutual gaze research. The first study in this thesis used eye-tracking to explore this hypothesis and investigate the relationship between mutual gaze and task performance. A suitable paradigm was developed, based on that used in previous research into eye movements and non-verbal communication. Two participants – Instruction Giver (IG) and Instruction Follower (IF) – communicated via avatars in Second Life to solve simple arithmetic tasks. There were two between-participant looking conditions: staring (the IG’s avatar stared continuously at the IF); and notstaring, (IG’s avatar looked at IF and task-relevant objects). Constant staring did, indeed, show evidence of decreasing mutual gaze within the dyad. Mutual gaze was positively correlated with task performance scores, but only in the not-staring condition. When not engaged in mutual gaze, the IF looked more at task-related objects in the not-staring condition than in the staring condition; this suggests that social factors are likely to be driving the gaze aversion in the staring condition. Furthermore, there are no task-related benefits to staring. The second study explored further how much looking by one person at another will maximise both mutual gaze and task performance between the dyad. It also investigated the relationship between mutual gaze, task performance and both manipulated and perceived social presence. Individual participants interacted with a virtual agent within the Second Life paradigm previously used in the human-human study. Participants were either told they were interacting with a computer (i.e. an agent) or another human (an avatar). This provided the between-participants manipulated social presence variable, or agency. The virtual agent was programmed to look at the participant during either 0%, 25%, 50% or 75% of the interaction, providing the within-participants variable looking condition. The majority of effects were found in the 75% looking condition, including the highest mutual gaze uptake and the highest social presence ratings (measured via a questionnaire). Although the questionnaire did not detect any differences in social presence between the agent and avatar condition, participants were significantly faster to complete the tasks in the avatar condition than in the agent condition. This suggests that behavioural measures may be more effective at detecting differences in social presence than questionnaires alone. The results are discussed in relation to different theories of social interaction. Implications and limitations of the findings are considered and suggestions for future work are made.