Realistic simulation and animation of clouds using SkewT-LogP diagrams

Nuvens e clima são tópicos importantes em computação gráfica, nomeadamente na simulação e animação de fenómenos naturais. Tal deve-se ao facto de a simulação de fenómenos naturais−onde as nuvens estão incluídas−encontrar aplicações em filmes, jogos e simuladores de voo. Contudo, as técnicas existentes em computação gráfica apenas permitem representações de nuvens simplificadas, tornadas possíveis através de dinâmicas fictícias que imitam a realidade. O problema que este trabalho pretende abordar prende-se com a simulação de nuvens adequadas para utilização em ambientes virtuais, isto é, nuvens com dinâmica baseada em física que variam ao longo do tempo. Em meteorologia é comum usar técnicas de simulação de nuvens baseadas em leis da física, contudoossistemasatmosféricosdeprediçãonuméricasãocomputacionalmente pesados e normalmente possuem maior precisão numérica do que o necessário em computação gráfica. Neste campo, torna-se necessário direcionar e ajustar as características físicas ou contornar a realidade de modo a atingir os objetivos artísticos, sendo um fator fundamental que faz com que a computação gráfica se distinga das ciências físicas. Contudo, simulações puramente baseadas em física geram soluções de acordo com regras predefinidas e tornam-se notoriamente difíceis de controlar. De modo a enfrentar esses desafios desenvolvemos um novo método de simulação de nuvens baseado em física que possui a característica de ser computacionalmente leve e simula as propriedades dinâmicas relacionadas com a formação de nuvens. Este novo modelo evita resolver as equações físicas, ao apresentar uma solução explícita para essas equações através de diagramas termodinâmicos SkewT/LogP. O sistema incorpora dados reais de forma a simular os parâmetros necessários para a formação de nuvens. É especialmente adequado para a simulação de nuvens cumulus que se formam devido ao um processo convectivo. Esta abordagem permite não só reduzir os custos computacionais de métodos baseados em física, mas também fornece a possibilidade de controlar a forma e dinâmica de nuvens através do controlo dos níveis atmosféricos existentes no diagrama SkewT/LogP. Nestatese,abordámostambémumoutrodesafio,queestárelacionadocomasimulação de nuvens orográficas. Do nosso conhecimento, esta é a primeira tentativa de simular a formação deste tipo de nuvens. A novidade deste método reside no fato de este tipo de nuvens serem não convectivas, oque se traduz nocálculodeoutrosníveis atmosféricos. Além disso, atendendo a que este tipo de nuvens se forma sobre montanhas, é também apresentadoumalgoritmoparadeterminarainfluênciadamontanhasobreomovimento da nuvem. Em resumo, esta dissertação apresenta um conjunto de algoritmos para a modelação e simulação de nuvens cumulus e orográficas, recorrendo a diagramas termodinâmicos SkewT/LogP pela primeira vez no campo da computação gráfica.Clouds and weather are important topics in computer graphics, in particular in the simulation and animation of natural phenomena. This is so because simulation of natural phenomena−where clouds are included−find applications in movies, games and flight simulators. However, existing techniques in computer graphics only offer the simplified cloud representations, possibly with fake dynamics that mimic the reality. The problem that this work addresses is how to find realistic simulation of cloud formation and evolution, that are suitable for virtual environments, i.e., clouds with physically-based dynamics over time. It happens that techniques for cloud simulation are available within the area of meteorology, but numerical weather prediction systems based on physics laws are computationally expensive and provide more numerical accuracy than the required accuracy in computer graphics. In computer graphics, we often need to direct and adjust physical features, or even to bend the reality, to meet artistic goals, which is a key factor that makes computer graphics distinct from physical sciences. However, pure physically-based simulations evolve their solutions according to pre-set physics rules that are notoriously difficult to control. In order to face these challenges we have developed a new lightweight physically-based cloudsimulationschemethatsimulatesthedynamicpropertiesofcloudformation. This new model avoids solving the physically-based equations typically used to simulate the formation of clouds by explicitly solving these equations using SkewT/LogP thermodynamic diagrams. The system incorporates a weather model that uses real data to simulate parameters related to cloud formation. This is specially suitable to the simulation of cumulus clouds, which result from a convective process. This approach not only reduces the computational costs of previous physically-based methods, but also provides a technique to control the shape and dynamics of clouds by handling the cloud levels in SkewT/LogP diagrams. In this thesis, we have also tackled a new challenge, which is related to the simulation oforographic clouds. From ourknowledge, this isthefirstattempttosimulatethis type of cloud formation. The novelty in this method relates to the fact that these clouds are non-convective, so that different atmospheric levels have to be determined. Moreover, since orographic clouds form over mountains, we have also to determine the mountain influence in the cloud motion. In summary, this thesis presents a set of algorithms for the modelling and simulation of cumulus and orographic clouds, taking advantage of the SkewT/LogP diagrams for the first time in the field of computer graphics

Métodos de representação virtual e visualização para informação arquitetónica e contextual em sítios arqueológicos

This work seeks to outline some guidelines in order to improve the use of 3D visualization applied to archaeological data of diverse nature and at different scales. One difficulty found in this process is related to the still frequent two-dimensional representation of the three-dimensional archaeological reality. Aware that the existence of data of two-dimensional nature is fundamental in the archaeological process and that they result, on the one hand, from the manual archaeological recording processes and, on the other hand, from the intense analysis and interpretation activity of the archaeological investigation team, we seek to ensure an adequate 3D representation based on 3D acquisition methods mostly available to the archaeology teams. Archaeological visualization in three-dimensional support is an increasingly frequent and necessary practice, but it continues to show some difficulties. These are substantiated in the reduced number of visualization techniques used, the use of visualization tools that are not very customized for the archaeological needs and the privileged use of visual features of the models during the archaeological process phases. Thus, the main objective of this work is to design and evaluate appropriate methods for visualizing archaeological data. To determine which visualization methods are most used during the phases of the archaeological process, an online user-survey was carried out, which allowed consolidating the 3D representation methodologies used, as well as to propose a visualization model that also categorizes the appropriate visualization techniques which increase the visual perception and understanding of the archaeological elements. Three prototypes are defined according to the different 3D data acquisition methodologies presented and visualization methodologies are designed in order to, on the one hand, take into account the scale and diversity of the archaeological elements and, on the other hand, to account for the need to ensure visualization methods which are easily assimilated by archaeologists. Each prototype was evaluated by two archaeologists with different professional background. They were proposed, through a set of previously determined tasks, to assess the interaction with 3D models and with the visualization methods and the satisfaction of the visualization results regarding the archaeological needs. The evaluation of the prototypes allowed to conclude that the presented visualization methods increase the perception of 3D models which represent archaeological elements. In addition, it was also possible to produce new objects that reveal elements of archaeological interest. It is suggested to make these methodologies available on a web-based application and on mobile platforms.Este trabalho procura esboçar algumas diretrizes no sentido de melhorar a utilização da visualização 3D aplicada aos dados arqueológicos de natureza diversa e a escalas distintas. Uma dificuldade encontrada neste processo prende-se com a, ainda frequente, representação bidimensional da realidade arqueológica tridimensional. Ciente de que a existência de dados de natureza bidimensional são fundamentais no processo arqueológico e que resultam, por um lado, dos processos manuais de registo arqueológicos e, por outro, da intensa atividade de análise e interpretação da equipa de investigação arqueológica, procuramos assegurar uma representação 3D adequada, com base em metodologias de aquisição de dados 3D geralmente disponíveis às equipas de arqueologia. A visualização arqueológica em suporte tridimensional é uma prática cada vez mais frequente e necessária, mas que continua a evidenciar algumas dificuldades. Estas substanciam-se no reduzido número de técnicas de visualização usadas, na utilização de ferramentas de visualização pouco adaptadas às necessidades arqueológicas e na utilização preferencial de características visuais dos modelos durante as fases do processo arqueológico. Assim, o objetivo primordial deste trabalho é desenhar e avaliar métodos adequados à visualização de dados arqueológicos. Para determinar que métodos de visualização são mais utilizados durante as fases do processo arqueológico realizou-se um questionário online que permitiu consolidar as metodologias de representação 3D usadas, bem como propor um modelo de visualização que também categoriza as técnicas de visualização adequadas para aumentar a perceção e a compreensão visual dos elementos arqueológicos. Definem-se três protótipos de acordo com as distintas metodologias de aquisição de dados 3D apresentados e são desenhadas metodologias de visualização que, por um lado, têm em conta a escala e a diversidade dos elementos arqueológicos e, por outro, a necessidade de assegurar métodos de visualização facilmente assimilados pelos arqueólogos. Cada protótipo foi avaliado por dois arqueólogos com experiências profissionais distintas. O que lhes foi proposto, através de um conjunto de tarefas previamente estabelecidas, foi aferir da facilidade de interação com os modelos 3D e com os métodos de visualização e adequação dos resultados de visualização às necessidades dos arqueólogos. A avaliação dos protótipos permitiu concluir que os métodos de visualização apresentados aumentam a perceção dos modelos 3D que representam elementos arqueológicos. Para além disso foi possível produzir também novos objetos que revelam elementos com interesse arqueológico. É sugerida a disponibilização destas metodologias em ambiente web e plataformas móveis.Programa Doutoral em Informátic

Recreational ecosystem service benefits from the Chestermere Lake Reservoir : value for day use non-resident visitors

x, 125 leaves : col. ill. ; 29 cmIrrigation infrastructure provides many ecosystem service (ES) benefits that enhance the well-being of Albertans and is central to economic activity in southern Alberta. Management of irrigation infrastructure and water resources is becoming increasingly challenging as Alberta’s population and economy grows. Past water allocation decisions have not generally considered the need of ecosystems leading to declining ecosystem health, and changes to provision of ES benefits in Alberta. The goals of current Alberta government policy include changing how water and land is managed to ensure that ecosystem health and ES provision is maintained. The research in this thesis concentrates on establishing the value of recreational ES benefits provided by the Chestermere Lake Reservoir, and obtaining information on the spatial aspects and visitor characteristics. A mixed method approach is used combining a qualitative discussion with a quantitative analysis using a geographic information system (GIS) and the travel cost method (TCM). The selection of the mixed method and combined GIS-TCM approach was based on past success in previous studies. The findings reveal a substantial value for recreational ES benefits provided by the Chestermere Lake Reservoir occurring within a limited area similar to other studies of recreational benefits from reservoirs. The findings of this research provide information for decisions makers, water infrastructure managers, and water transfer participants when assessing the impact of planned actions. Further research is recommended to build upon the findings of this study and further expand the available information on ES benefits to include all ES provided by southern Alberta

Assessing the Influence and Effectiveness of Watershed Report Cards on Watershed Management: A Study of Watershed Organizations in Canada

The concept and practice of watershed management have evolved since the early twentieth century and continue to change. Contemporary watershed management, as a means to improve environmental, social, and economic well-being, is generally accepted world-wide and is gaining popularity. Recognition of the ever-changing, complex, conflicting, and unpredictable nature of the forces that influence ecological and human systems has given rise to concepts and principles related to ecological or watershed health, sustainability, and good governance. Numerous terms have emerged to describe and explain contemporary watershed management processes that incorporate these concepts and principles, including ‘integrated’ and ‘sustainable’ watershed management. While there is growing consensus that integrated or sustainable watershed management should be practiced, there is little agreement on what these two terms mean and how they differ. The rational comprehensive or synoptic model is a widely-accepted normative framework to guide watershed management processes. This model presumes a ‘top-down’ linear, systematic, and logical sequence of steps characterized by complete knowledge of the issues and consequences of actions and dominated by rational decision making – circumstances that rarely happen in real life. Implementation gaps between theory and practice exist because of persistent and common challenges relating to complexity, conflict, uncertainty, and change in human and ecological systems. Failure to account for these factors has restricted the utility of this model for guiding watershed management processes, prompting questions about how the model might be adjusted to incorporate concepts and principles associated with watershed health, sustainability, and good governance. In response to the need to demonstrate progress towards watershed health and sustainability, a growing number of watershed organizations in Canada are pioneering the development of indicator-based assessment reports. The actual versus anticipated outcomes of watershed indicator reports and their existing and potential role in the watershed management process have not been systematically assessed or compared. A review of academic and professional literature and a mixed methods research approach comparing 13 case studies from 7 provinces across Canada were used to explore these knowledge gaps. A more in-depth investigation of two of the case studies, the Fraser Basin Council and the Humber Watershed Alliance, was also completed. Contextual factors influencing the practice of watershed management and the process used for developing watershed report cards are identified through an analysis of available documents. This information is supplemented with opinions gathered from 109 in-depth and semi-structured interviews/questionnaires. In addition, informants provided viewpoints regarding the usefulness, effectiveness, benefits, and value of watershed report cards, along with ideas about how they can be improved. This study concludes that while sustainable watershed management (SWM) and integrated watershed management (IWM) are closely aligned concepts, the distinguishing factor is scope. The primary goal of SWM is environmental, social, and economic sustainability within a watershed unit, whereas the central focus of IWM is the protection and/or restoration of water and land resources within a watershed to sustain human well-being. In Canada, IWM rather than SWM is generally pursued. Nevertheless, sustainability is an ultimate goal of IWM. Sustainability principles are acknowledged, valued, and applied. This study concludes that IWM can play a significant role in supporting a broad sustainability agenda. This study contributes to a growing body of knowledge seeking to enrich the theory of watershed management and improve and streamline practice. To improve the utility of the rational comprehensive model for guiding contemporary watershed management, modifications are presented which include separate phases for visioning and learning and couch the process within an overall conceptual framework that balances management, research, and monitoring activities. These adjustments reflect the concepts of integration, collaboration, and shared learning and acknowledge the shift away from ‘command and control’ bureaucratic processes to collaborative ‘middle ground’ polycentric governance structures. Rather than focusing strictly on a sequence of steps and a prescribed process, the consideration of a series of context-specific questions is advocated to help scope and streamline processes to match stakeholder capacity, address issues of greatest concern, and sustain interest and enthusiasm. However, concerted effort is required to counteract competing and entrenched socio-political and economic doctrines and traditions. Monitoring, evaluating, and reporting are key components in the IWM process. Study findings reveal that watershed report cards in Canada are a fledgling tool and no standard approach exists. Each case-study watershed organization has a unique approach to selecting, organizing, and presenting indicators. As a result, report card styles and formats vary. Despite a general consensus that watershed report cards are worthwhile, expectations often exceed outcomes, and common traits which challenge their effectiveness exist. The usefulness and effectiveness of watershed report cards are hampered by several common shortfalls: (1) universal lack of consistent, spatially-specific, and timely data, (2) inconsistent measures and indicators between successive watershed reports, (3) ambiguous or non-existent goals, objectives, targets, and benchmarks, and (4) messages that are unclear, difficult to understand, or fail to resonate with the target audiences. The ‘lessons learned’ from an assessment of the attributes and perceived benefits of watershed report cards parallel those discovered for community indicator initiatives. Building on this research, recommendations for improvement include (1) focus on stakeholder issues of prime concern, (2) use consistent measures and indicators, (3) limit the number of indicators and simplify report card styles and formats, (4) select spatially explicit, temporally relevant, and science-based indicators and measures, (5) explain and illustrate major cause-effect linkages, (6) use the report card process to build a constituency of support, (7) incorporate marketing and outreach activities, and (8) introduce performance measures to assess efficiency and how well collective practice demonstrates sustainability principles. This study concludes that opportunities exist for improving watershed report cards and boosting their multi-purpose role as a predominant planning, assessment, advocacy, communication, learning, and research tool in support of IWM, and ultimately, sustainability

Display computers

A Display Computer (DC) is an everyday object: Display Computer = Display + Computer. The “Display” part is the standard viewing surface found on everyday objects that conveys information or art. The “Computer” is found on the same everyday object; but by its ubiquitous nature, it will be relatively unnoticeable by the DC user, as it is manufactured “in the margins”. A DC may be mobile, moving with us as part of the everyday object we are using. DCs will be ubiquitous: “effectively invisible”, available at a glance, and seamlessly integrated into the environment. A DC should be an example of Weiser’s calm technology: encalming to the user, providing peripheral awareness without information overload. A DC should provide unremarkable computing in support of our daily routines in life. The nbaCub (nightly bedtime ambient Cues utility buddy) prototype illustrates a sample application of how DCs can be useful in the everyday environment of the home of the future. Embedding a computer into a toy, such that the display is the only visible portion, can present many opportunities for seamless and nontraditional uses of computing technology for our youngest user community. A field study was conducted in the home environment of a five-year old child over ten consecutive weeks as an informal, proof of concept of what Display Computers for children can look like and be used for in the near future. The personalized nbaCub provided lightweight, ambient information during the necessary daily routines of preparing for bed (evening routine) and preparing to go to school (morning routine). To further understand the child’s progress towards learning abstract concepts of time passage and routines, a novel “test by design” activity was included. Here, the role of the subject changed to primary designer/director. Final post-testing showed the subject knew both morning and bedtime routines very well and correctly answered seven of eight questions based on abstract images of time passage. Thus, the subject was in the process of learning the more abstract concept of time passage, but was not totally comfortable with the idea at the end of the study

Enhancing Volunteered Geographical Information (VGI) Visualization with Open Source Web-Based Software

Recent advances in information technology such as Web mapping and location-aware mobile devices have enabled non-experts to create, use and share volumes of spatial data in an increasingly accessible fashion. Such user-generated spatial data is usually referred to as Volunteered Geographic Information (VGI). Two of the fundamental challenges associated with the exploitation of VGI relate to information overload and extraction of meaning. In order to deal with these challenges and improve the utility of VGI, this thesis investigates the potential of several interactive geovisualization techniques including filtering, dynamic spatial aggregation, linking and brushing, and tag-based visualizations. As a preliminary work to explore and structure the new research field of VGI, a framework of the different types of VGI is elaborated and followed by a review of the challenges and current solutions related to the utilization of VGI. Based on this review, a web-based prototype is developed to serve as a platform for the evaluation of selected geovisualization techniques. The prototype is then used in a series of workshops with rich citizen-generated data related to place-based community assets. The results of the case study show that the implemented geovisualization techniques enable users to find relevant subsets of information and to gain new insights on the data. Based on the potential shown by these results, future research directions are suggested