This thesis explores the issues involved in modeling and rendering virtual environments with special emphasis on photo-realistic visualization and optimizing models for real-time applications. Architectural walk-through systems are expected to give convincingly realistic interactive visualizations of complex virtual environments (Brooks, 1986). This pursued high degree impression of reality enhanced by interactivity, leads the user into a state of immersion, or the suspension of disbelief. The use of these systems ranges from virtual prototyping of building designs, stage and set lighting design, and architectural design reviews where the demands for greater realism and higher frame rates are always increasing. Until recently, the major focus has been on quickly rendering a complex model, rather than on photo-realism. The primary goal was reducing the number of graphics primitives rendered per frame without noticeably degrading image quality. The aim of this research is to study some of the real-time rendering and illumination techniques, bringing out the limitations and advantages of each. In addition the study investigates the extent of inclusion of standard 3 Dimensional modeling packages in the methodology pipeline, providing architects and designers with some guidelines for photo-realistic visualization and real-time simulation of their models. This is demonstrated through an example model of Tadao Ando's Church on the Water. A 3D photo-realistic reconstruction and real-time simulation is attempted, using widely available standard tools. The aim is to develop a methodology for building a compelling, interactive and highly realistic virtual representation. The whole methodology is based not on proprietary commercial 3D game engines, but on international open standard programming languages and API's, while leaving the user to freely select and use his/her 3D character-modeling package of choice. However, several shortcomings in both hardware and software became apparent. These are described, and a number of recommendations are provided. / Master of Science

No / The first recorded crowdsourcing activity was in 1714 [1], with intermittent public event occurrences up until the millennium when such activities become widespread, spanning multiple domains. Crowdsourcing, however, is relatively novel as a methodology within virtual environment studies, in archaeology, and within the heritage domains where this research is focused. The studies that are being conducted are few and far between in comparison to other areas. This paper aims to develop a recent concept in crowdsourcing work termed `crowd behaviour mining' [2] using virtual environments, and to develop a unique concept in crowdsourcing activities that can be applied beyond the case studies presented here and to other domains that involve human behaviour as independent variables. The case studies described here use data from experiments involving separate heritage projects and conducted during two Royal Society Summer Science Exhibitions, in 2012 and 2015 respectively. `Crowd Behaviour Mining' analysis demonstrated a capacity to inform research in respect of potential patterns and trends across space and time as well as preferences between demographic user groups and the influence of experimenters during the experiments.

This study examined the role of home environments in the cognitive and behavioral outcomes of children born to teenage mothers. The sample consisted of 1,011 firstborn children aged 6 to 18 and their mothers selected from the 1990 National Longitudinal Survey of Youth (NLSY). Multivariate regression analyses revealed that the quality of home environments mediated the effects of father presence on the behavioral adjustment of children, even taking other socio-demographic and maternal characteristics into account. Moreover, the results showed that the home environment was the best predictor for both the academic achievement and the behavioral problems of children even after controlling for such background factors as family income, number of children, maternal education, and self-esteem. Also, when other variables in the model were statistically accounted for, the mothers' age at first birth was unrelated to the quality of home environments, and with controlling for the home environment, it was not a significant predictor of either the cognitive attainment or the behavioral adjustment of children. The findings evidence the importance of home environments for the optimal development of children, and suggest that strong home environments contribute to prevent potential negative outcomes and promote positive developmental outcomes of children born to teenage mothers. / Ph. D.

This dissertation aimed to expand knowledge and practical uses of educational technology tools in high-stakes team training environments. This study depicted the real-world impacts of virtual reality (VR) technology on learning and training for the Royal New Zealand Police Academy and those training teams in high-stakes environments. Recommendations for improvement in designing these technologies and training resulted from the study. The study involving VR and the Bedford Workload Scale employed pre- and post-training to determine if using that technology produced statistical significance and improved user learning in VR tactical police training. The final study resulted in similar pre- and post-test results from participants (n = 74), indicating VR may produce realistic levels of cognitive load in virtual participants, and one statistically significant finding for participants who had previous experience using VR, suggesting that cognitive load may be higher during training for those with previous experience. The findings revealed that VR shows promise for increasing the value and efficacy of compliance training in tactical police settings and similar high-stakes team training environments.

Ram pressure stripping is a well-known galactic quenching mechanism capable of removing star-forming gas from a galaxy as it falls into a group or cluster. However, prior to stripping, ram pressure can induce brief periods of enhanced star formation by compressing the gas on the leading side of an infalling galaxy. Studies of this phenomenon have focused primarily on a unique population of galaxies for which a stripped tail of gas opposing the direction of motion is visible, known as jellyfish galaxies. The role of this effect in galaxy evolution overall is currently unknown. This thesis investigates the importance of ram pressure-induced star formation across all infalling galaxies to generalize our understanding of the effect. We use several metrics to measure the star formation asymmetries of a large sample of group and cluster galaxies in the Sloan Digital Sky Survey using $u$-band imaging from the Canada-France Imaging Survey as a tracer for star formation rate. We find that the distributions of star formation asymmetries of satellite galaxies are indistinguishable from those of a control sample of isolated field galaxies. Subdividing the sample by host halo mass and time since infall, we still find no environmental dependence of ram pressure as an enhancer of star formation. We conclude that any statistical star formation enhancement is small for infalling galaxies, suggesting that this effect is either uncommon or short-lived. / Thesis / Master of Science (MSc)

This research empirically investigated the Video Game Experience Measure (VGEM), which captures general aspects of video game experience in a five-factor model, tapping factors such as frequency and intensity of gameplay, and self-reported confidence in specific game-related skills as well as more general self-efficacy. The VGEM captures facets of video game experience that have been represented in prior research, and which have individually been found to relate to players’ gameplay performance. These factors of individuals’ video game experience have been found to introduce notable variance in game-based experimentation, but the extent to which each aspect impacts performance has been sparsely researched. This study used well-established basic cognitive research tasks to investigate whether the VGEM is able to discriminate between individuals’ prior experience along different factors or dimensions of video gameplay, and whether the measure is able to account for variance in cognitive task performance on three cognitive tasks, including Fitts’ Law task, a measure of hand-eye coordination and reaction time, Task-Switching and Mixing task, a measure of cognitive flexibility, and Stroop task, a measure of attention and cognitive inhibition. Additionally, demographic factors such as sex and age are investigated as they relate to cognitive task performance. This study’s participants were undergraduate students at the University of Central Florida who volunteered to participate through the UCF Psychology SONA system recruitment system in exchange for course credit, the final dataset contained 295 participants. Results showed that the Video Game Experience Measure factors explained a significant proportion of the variance in cognitive task performance in this sample and were generally more predictive of performance than demographic factors. Findings from this research demonstrate that the Video Game Experience Measure may be used to more accurately account for variance in novel game-based task performance in experimental study samples, provide insight into factors related to aspects of video game experience, and elucidate differences between, in addition to non-players, types of players that emerge from combinations of demographic, motivational, and experiential factors.

O nível de perturbação a que um ambiente está sujeito pode afetar profundamente o processo de regeneração natural, através de modificações nas fontes de regeneração. Os principais mecanismos de regeneração natural das florestas são a chuva de sementes (dispersão), o banco de sementes do solo e o estabelecimento de plântulas. O presente estudo tem como objetivo analisar uma das principais etapas da regeneração, a chuva de sementes, em áreas de perturbações naturais (clareiras) e antrópicas (área queimada) e áreas sem indícios de perturbação recente na Mata Atlântica do sul da Bahia. Para a amostragem, foram instalados coletores de sementes em ambientes de sub-bosque, de clareiras naturais e de uma área perturbada por fogo, num total de 144 coletores de 0,50 x 0,50 m, amostrados mensalmente. A chuva de sementes da Floresta Ombrófila Densa analisada foi contínua ao longo dos dois anos amostrados, mas apresentou flutuações entre períodos do ano e variações entre os ambientes analisados. Foram amostradas 41.910 sementes, pertencentes a 198 morfoespécies, sendo que as 120 que puderam ser identificadas foram distribuídas em 31 famílias e 57 gêneros. As 78 espécies indeterminadas representam apenas 256 sementes ou 0,6% do total de sementes amostradas. A menor quantidade total de sementes nesses dois anos foi observada no ambiente de clareiras (7.555, representando 1,25 sementes/m²/dia), enquanto o maior número de sementes foi observado na área queimada (13.656, ou seja, 2,17 sementes/m²/dia). Não foram constatadas diferenças significativas entre a proporção de espécies anemocóricas para os ambientes de clareiras e sub-bosque em nenhum dos anos analisados. Os ambientes mais similares foram o sub-bosque próximo à área queimada (MP) e o subbosque adjacente às clareiras (SB), seguido pelas clareiras (C) e pelo sub-bosque próximo à área queimada (MP). Os períodos de maior taxa de deposição de sementes estiveram concentrados principalmente no meio de ano para praticamente todos os ambientes. A chuva de sementes foi dominada por um pequeno número de espécies produzindo cerca de 98% do total de sementes amostradas, e com muitas espécies sendo representadas por poucas sementes ao longo do período de estudo. Essa dominância foi representada principalmente por três espécies arbóreas pioneiras nativas: Miconia mirabilis, Cecropia pachystachya e Henriettea succosa. Em análise mais detalhada da chuva de sementes destas espécies foi observado que as espécies Miconia mirabilis e Cecropia pachystachya mostraram um padrão anual de deposição de suas sementes, sugerindo que estas espécies possuem uma fenologia definida com longos períodos de deposição de sementes durante o ano. Henriettea succosa foi a espécie que obteve uma distribuição mais homogênea entre os quatros ambientes observados, porém sua maior deposição de sementes ocorreu exclusivamente no mês de abril de 1999. / The disturbance level to which a forest is exposed to may affect its dynamics, modifying the recruits sources. The main mechanisms of forest natural regeneration is seed rain (dispersion), soil seed bank and seedlings establishment. This study aims to analyze seed rain within fire and natural (gaps) disturbed areas and sites with no sign of recent disturb at Atlantic Forests of South Bahia. Sampling was taken monthly through seed rain collectors located under gaps, understorey and fire disturbed areas, in a total of 144 0,5x0,5 m collectors. Although seed rain sampling was continuous, fluctuations were noticed for distinct seasonal periods and environments. A total of 41.910 seeds were sampled, representing 198 morfo-species; 120 were identified and classified into 31 botanical families and 57 genera. The remaining 78 morfo-species were represented by 256 seeds or 0,6% of total sampled seeds. The lower quantities of seeds were observed within gaps environments (7.555 seeds, representing 1,25 seeds/m²/day), while the higher amounts were observed for the fire disturbed areas (13.656 seeds or 2,17 seeds/m²/day). No significant differences were found regarding anemochoric species occurrence between gaps and understorey environments. Similarities were found between fire disturbed areas (MP) and their surrounding understorey environments (SB) and also between gaps (C) and understorey close to fire disturbed areas (SB). The periods of seeds deposition higher rate had been mainly concentrated in the middle of the year for practically all environments. Seed rain was characterized by few species that produced around 98% of the total amount of sampled seeds, with most of the species being represented by few seeds during this study. The dominant species were represented by three native pioneer tree species: Miconia mirabilis, Cecropia pachystachya and Henriettea succosa. A more detailed analysis of the seed rain revealed that Miconia mirabilis and Cecropia pachystachya have an annual deposition pattern, suggesting that these species have a defined phenology, with long periods of seeds deposition along a year. Henriettea succosa presented the most homogeneous distribution among the observed environments, with higher levels of deposition during April 1999. Further studies are needed to understand the observed patterns of this study, especially on M. mirabilis and C. pachystachya phenology.

O nível de perturbação a que um ambiente está sujeito pode afetar profundamente o processo de regeneração natural, através de modificações nas fontes de regeneração. Os principais mecanismos de regeneração natural das florestas são a chuva de sementes (dispersão), o banco de sementes do solo e o estabelecimento de plântulas. O presente estudo tem como objetivo analisar uma das principais etapas da regeneração, a chuva de sementes, em áreas de perturbações naturais (clareiras) e antrópicas (área queimada) e áreas sem indícios de perturbação recente na Mata Atlântica do sul da Bahia. Para a amostragem, foram instalados coletores de sementes em ambientes de sub-bosque, de clareiras naturais e de uma área perturbada por fogo, num total de 144 coletores de 0,50 x 0,50 m, amostrados mensalmente. A chuva de sementes da Floresta Ombrófila Densa analisada foi contínua ao longo dos dois anos amostrados, mas apresentou flutuações entre períodos do ano e variações entre os ambientes analisados. Foram amostradas 41.910 sementes, pertencentes a 198 morfoespécies, sendo que as 120 que puderam ser identificadas foram distribuídas em 31 famílias e 57 gêneros. As 78 espécies indeterminadas representam apenas 256 sementes ou 0,6% do total de sementes amostradas. A menor quantidade total de sementes nesses dois anos foi observada no ambiente de clareiras (7.555, representando 1,25 sementes/m²/dia), enquanto o maior número de sementes foi observado na área queimada (13.656, ou seja, 2,17 sementes/m²/dia). Não foram constatadas diferenças significativas entre a proporção de espécies anemocóricas para os ambientes de clareiras e sub-bosque em nenhum dos anos analisados. Os ambientes mais similares foram o sub-bosque próximo à área queimada (MP) e o subbosque adjacente às clareiras (SB), seguido pelas clareiras (C) e pelo sub-bosque próximo à área queimada (MP). Os períodos de maior taxa de deposição de sementes estiveram concentrados principalmente no meio de ano para praticamente todos os ambientes. A chuva de sementes foi dominada por um pequeno número de espécies produzindo cerca de 98% do total de sementes amostradas, e com muitas espécies sendo representadas por poucas sementes ao longo do período de estudo. Essa dominância foi representada principalmente por três espécies arbóreas pioneiras nativas: Miconia mirabilis, Cecropia pachystachya e Henriettea succosa. Em análise mais detalhada da chuva de sementes destas espécies foi observado que as espécies Miconia mirabilis e Cecropia pachystachya mostraram um padrão anual de deposição de suas sementes, sugerindo que estas espécies possuem uma fenologia definida com longos períodos de deposição de sementes durante o ano. Henriettea succosa foi a espécie que obteve uma distribuição mais homogênea entre os quatros ambientes observados, porém sua maior deposição de sementes ocorreu exclusivamente no mês de abril de 1999. / The disturbance level to which a forest is exposed to may affect its dynamics, modifying the recruits sources. The main mechanisms of forest natural regeneration is seed rain (dispersion), soil seed bank and seedlings establishment. This study aims to analyze seed rain within fire and natural (gaps) disturbed areas and sites with no sign of recent disturb at Atlantic Forests of South Bahia. Sampling was taken monthly through seed rain collectors located under gaps, understorey and fire disturbed areas, in a total of 144 0,5x0,5 m collectors. Although seed rain sampling was continuous, fluctuations were noticed for distinct seasonal periods and environments. A total of 41.910 seeds were sampled, representing 198 morfo-species; 120 were identified and classified into 31 botanical families and 57 genera. The remaining 78 morfo-species were represented by 256 seeds or 0,6% of total sampled seeds. The lower quantities of seeds were observed within gaps environments (7.555 seeds, representing 1,25 seeds/m²/day), while the higher amounts were observed for the fire disturbed areas (13.656 seeds or 2,17 seeds/m²/day). No significant differences were found regarding anemochoric species occurrence between gaps and understorey environments. Similarities were found between fire disturbed areas (MP) and their surrounding understorey environments (SB) and also between gaps (C) and understorey close to fire disturbed areas (SB). The periods of seeds deposition higher rate had been mainly concentrated in the middle of the year for practically all environments. Seed rain was characterized by few species that produced around 98% of the total amount of sampled seeds, with most of the species being represented by few seeds during this study. The dominant species were represented by three native pioneer tree species: Miconia mirabilis, Cecropia pachystachya and Henriettea succosa. A more detailed analysis of the seed rain revealed that Miconia mirabilis and Cecropia pachystachya have an annual deposition pattern, suggesting that these species have a defined phenology, with long periods of seeds deposition along a year. Henriettea succosa presented the most homogeneous distribution among the observed environments, with higher levels of deposition during April 1999. Further studies are needed to understand the observed patterns of this study, especially on M. mirabilis and C. pachystachya phenology.

A realização de videoconferências sem o uso de equipamentos que possuam tecnologia proprietária ou sem o uso de redes não comerciais (como a Internet 2) ou com características não comuns (como o protocolo Multicast) tem se revelado um desafio para os estudiosos do assunto. Este trabalho apresenta uma proposta de solução desse problema demonstrando que é possível estabelecer-se uma videoconferência entre muitas salas sobre a Internet 1, com qualidade de serviço, usando equipamentos comerciais comuns de informática e sem sobrecarga da rede. Para isso, por intermédio da integração de duas tecnologias grid (AccessGrid e Grid Delivery), são propostas as bases de uma nova versão de Access Grid, chamado MPAG (MultiPeer Access Grid). / The development of videoconferencing without the use of equipments with customized technology or without commercial networks (like Internet 2) or without common characteristics (as Multicast, for instance) has appeared as a challenge to the subject researchers. This work presents a proposal of solution to this problem, showing that is possible to create a videoconference between many rooms under the Internet 1, with quality of service, using common commercial computing equipments and without overloading the network. For this, two technologies of grid (AccessGrid and Grid Delivery) have been integrated, proposing the basis of a new version of Access Grid, called MPAG (MultiPeer Access Grid).

This thesis is concerned with the robots' motion planning problem. In particular it is focused on the path planning and motion planning for Autonomously Guided Vehicles (AGVs) in well-structured, two-dimensional static and dynamic environments. Two algorithms are proposed for solving the aforementioned problems. The first algorithm establishes the shortest collision-semi-free path for an AGV from its start point to its goal point, in a two-dimensional static environment populated by simple polygonal obstacles. This algorithm constructs and searches a reduced visibility graph, within the AGV's configuration space, using heuristic information about the problem domain. The second algorithm establishes the time minimal collision-semi-free motion for an AGV, from its start point to is goal point, in a two-dimensional dynamic environment populated by simple polygonal obstacles. This algorithm considers the AGV's spacetime configuration space, thus reducing the dynamic motion planning problem to the static path planning problem. A reduced visibility graph is then constructed and searched using information about the problem domain, in the AGV's space-time configuration space in order to establish the time-minimal motion between the AGV's start and goal configurations. The latter algorithm is extended to solve more complicated instances of the dynamic motion planning problem, where the AGV's environment is populated by obstacles, which change their size as well as their position over time and obstacles, which have piecewise linear motion. The proposed algorithms can be used to efficiently and safely navigate AGVs in well structured environments. For example, for the navigation of an AGV, in industrial environments, where it operates as part of the manufacturing process or in chemical and nuclear plants, where the hostile environment is inaccessible to humans. The main contributions in this thesis are, the systematic study of the V*GRAPH algorithm and identification of its methodic and algorithmic deficiencies; recommendation of corrections and further improvements on the V* GRAPH algorithm, which in turn lead to the proposition of the V*MECHA algorithm for robot path planning; proposition of the D*MECHA algorithm for motion planning in dynamic environments; extension to the D*MECHA algorithm to solve more complicated instances of the dynamic robot motion planning problem; discussion of formal proofs of the proposed algorithms' correctness and optimality and critical comparisons with existing similar algorithms for solving the motion planning problem.