Produzir imagens de alta qualidade por computador, no menor tempo possível, que sejam convincentes ao público alvo, utilizando-se de maneira ótima todos os recursos computacionais à disposição, é uma tarefa que envolve uma cadeia de processos específicos, sendo um grande desafio ainda nos dias de hoje. O presente trabalho apresenta um estudo sobre toda esta cadeia de processos, com foco na avaliação de métodos de Iluminação Global empregados na Síntese de Imagens fotorrealistas para as áreas de Animação e Efeitos Visuais. Com o objetivo de auxiliar o usuário na tarefa de produzir imagens fotorrealistas de alta qualidade, foram realizados experimentos envolvendo diversas cenas de teste e seis métodos de Iluminação Global do Estado da Arte: Path Tracing, Light Tracing, Bidirectional Path Tracing, Metropolis Light Transport, Progressive Photon Mapping e Vertex Connection and Merging. O sintetizador escolhido para execução do experimento foi o Mitsuba Renderer. Para avaliação da qualidade dos resultados, duas métricas perceptuais foram adotadas: o Índice de Similaridade Estrutural SSIM e o Previsor de Diferenças Visuais HDR-VDP-2. A partir da avaliação dos resultados, foi construído um Guia de Recomendações para o usuário, indicando, com base nas características de uma cena arbitrária, o método de Iluminação Global mais adequado para realizar a síntese das imagens. Por fim, foram apontados caminhos de pesquisa para trabalhos futuros, sugerindo o emprego de classificadores, métodos de redução de parâmetros e Inteligência Artificial a fim de automatizar o processo de produção de imagens fotorrealistas e de alta qualidade. / The task of generating high quality computer images in the shortest time possible, believable to the targets audience perception, using all computational resources available, is still a challenging procedure, composed by a chain of specific processes. This work presents a study of this chain, focusing on the evaluation of Global Illumination methods used on the Synthesis of Photorealistic Images, in the areas of Animation and Visual Effects. To achieve the goal of helping users to produce high-quality photorealistic images, two experiments were proposed containing several test scenes and six State-of-the-Art Global Illumination methods: Path Tracing, Light Tracing, Bidirectional Path Tracing, Metropolis Light Transport, Progressive Photon Mapping and Vertex Connection and Merging. In order to execute the tests, the open source renderer Mitsuba was used. The quality of the produced images was analyzed using two different perceptual metrics: Structural Similarity Index SSIM and Visual Difference Predictor HDR-VDP-2. By analyzing results, a Recommendation Guide was created, providing suggestions, based on an arbitrary scenes characteristics, of the most suitable Global Illumination method to be used in order to synthesize images from the given scene. In the end, future ways of research are presented, proposing the use of classifiers, parameter reduction methods and Artificial Intelligence, in order to build an automatic procedure to generate high quality photorealistic images.

Esta dissertação propõe uma leitura sobre o tema da iluminação artificial, destacando o seu papel em espaços museográficos, por estes elevarem a um expoente máximo, as potencialidades e exigências do desenho da luz. No final do século XVIII, quando os museus começaram a surgir como veículos de divulgação cultural, o seu funcionamento dependia das condições da luz natural. Na transição para o século XX, uma das grandes transformações nesses espaços resultou da introdução da iluminação elétrica, cujo desempenho, desde então, não cessou de melhorar. Hoje, a tecnologia LED surpreende-nos com resultados quantitativos e qualitativos inéditos. Em pleno século XXI, com a atual evolução das sociedades, das tecnologias e das condições ambientais mundiais, enfrentamos um novo momento de viragem. Neste sentido, a pesquisa elegeu cinco tópicos gerais de análise cuja reflexão, em nossa opinião, revela-se determinante para o resultado do projeto de iluminação de um museu contemporâneo. Começa-se pelas Pessoas, porque a luz é, antes de tudo, um elemento essencial à condição humana e, a sua vertente artificial, resulta da invenção do homem. Explora-se o tema da Arquitetura, cujas formas apenas são perceptíveis sob o efeito da luz, originando esta relação indissociável. Avalia-se o Contexto, uma vez que as condicionantes locais influenciam qualquer projeto, mesmo o de iluminação. Prossegue-se com a Tecnologia, indispensável para o desenvolvimento de uma intervenção contemporânea. Enfim, examina-se a Obra de arte, o foco derradeiro de uma exposição museográfica, por excelência. Por último, alguns exemplos contemporâneos procuram ilustrar os temas explorados. E é das iniciais desses cinco temas que surge a palavra-síntese deste trabalho: PACTO. Com efeito, acreditamos que o triunfo do projeto de iluminação museográfico dependerá do pacto, por outras palavras, do acordo e da sintonia entre os elementos cruciais envolvidos no processo: as Pessoas, a Arquitetura, o Contexto, a Tecnologia e a Obra de arte. Através de uma metodologia apoiada na permanente atualização teórica com bibliografia específica, mas acima de tudo, numa participação ativa em conferências e workshops internacionais especializados sobre o tema, procuramos absorver e aqui relatar as mais recentes descobertas e aplicações práticas de um elemento tão dinâmico e interdisciplinar como é a luz artificial. Num museu do século XXI, além da inevitabilidade do pensamento sustentável e eficiente, junta-se ao processo o desafio de adequadamente valorizar a arquitetura, enaltecer as obras de arte com máxima preservação e, com toda a sensibilidade possível, tornar a experiência do visitante funcional e, principalmente, inesquecível. / This work proposes a reading about artificial lighting, emphasizing its role in museographic spaces that raise, in a maximum exponent, the potential and exigencies of lighting design. In the late XVIII century, when the museums began to emerge as cultural spreading vehicles, their operation depended on the natural light conditions. In the transition to the XX century, one of the major changes in those spaces resulted from the introduction of electric lighting, whose performance didn\'t stop to improve since then. Today, LED technology surprises us with unprecedented quantitative and qualitative results. In the XXI century, with the current evolution of societies, technologies and global environmental conditions, we are facing a new turning point. In this sense, this research selected five general topics of analysis whose reflection, in our opinion, is decisive to contemporary museum lighting design results. It begins with People, because, first of all, light is an essential element for the human condition and the artificial version is its own invention. It explores the Architecture theme, whose forms are only perceptible under light, resulting in this inseparable relationship. It evaluates the Context, since the local conditions affect any project, even the lighting design one. It continues with Technology, essential for the development of any contemporary intervention. It examines the Artwork, the ultimate focus of a museum-exhibition, par excellence. Finally, some contemporary examples try to illustrate the explored themes. And with the initials of those five themes it comes the word that synthesizes this work: PACTO (in english: PACT). Actually, we believe that the triumph of a museum\'s lighting project will depend on the pact, in other words, the agreement and the harmony between the five crucial elements involved in the process: People, Architecture, Context, Technology and Artwork. Through a methodology supported by the permanent theoretical update with specific bibliography, but mainly through an active participation in international conferences and workshops specialized on this topic, we tried to absorb and here report the most recent discoveries and practical applications of such a dynamic and interdisciplinary element as artificial light. Besides the sustainable and efficient thinking, a 21st century museum must add to the process the challenge of adequately enhance the architecture, rise the art works perception with maximum preservation and, with total sensitivity, make the visitor experience functional and, above all, unforgettable.

Esta dissertação propõe uma leitura sobre o tema da iluminação artificial, destacando o seu papel em espaços museográficos, por estes elevarem a um expoente máximo, as potencialidades e exigências do desenho da luz. No final do século XVIII, quando os museus começaram a surgir como veículos de divulgação cultural, o seu funcionamento dependia das condições da luz natural. Na transição para o século XX, uma das grandes transformações nesses espaços resultou da introdução da iluminação elétrica, cujo desempenho, desde então, não cessou de melhorar. Hoje, a tecnologia LED surpreende-nos com resultados quantitativos e qualitativos inéditos. Em pleno século XXI, com a atual evolução das sociedades, das tecnologias e das condições ambientais mundiais, enfrentamos um novo momento de viragem. Neste sentido, a pesquisa elegeu cinco tópicos gerais de análise cuja reflexão, em nossa opinião, revela-se determinante para o resultado do projeto de iluminação de um museu contemporâneo. Começa-se pelas Pessoas, porque a luz é, antes de tudo, um elemento essencial à condição humana e, a sua vertente artificial, resulta da invenção do homem. Explora-se o tema da Arquitetura, cujas formas apenas são perceptíveis sob o efeito da luz, originando esta relação indissociável. Avalia-se o Contexto, uma vez que as condicionantes locais influenciam qualquer projeto, mesmo o de iluminação. Prossegue-se com a Tecnologia, indispensável para o desenvolvimento de uma intervenção contemporânea. Enfim, examina-se a Obra de arte, o foco derradeiro de uma exposição museográfica, por excelência. Por último, alguns exemplos contemporâneos procuram ilustrar os temas explorados. E é das iniciais desses cinco temas que surge a palavra-síntese deste trabalho: PACTO. Com efeito, acreditamos que o triunfo do projeto de iluminação museográfico dependerá do pacto, por outras palavras, do acordo e da sintonia entre os elementos cruciais envolvidos no processo: as Pessoas, a Arquitetura, o Contexto, a Tecnologia e a Obra de arte. Através de uma metodologia apoiada na permanente atualização teórica com bibliografia específica, mas acima de tudo, numa participação ativa em conferências e workshops internacionais especializados sobre o tema, procuramos absorver e aqui relatar as mais recentes descobertas e aplicações práticas de um elemento tão dinâmico e interdisciplinar como é a luz artificial. Num museu do século XXI, além da inevitabilidade do pensamento sustentável e eficiente, junta-se ao processo o desafio de adequadamente valorizar a arquitetura, enaltecer as obras de arte com máxima preservação e, com toda a sensibilidade possível, tornar a experiência do visitante funcional e, principalmente, inesquecível. / This work proposes a reading about artificial lighting, emphasizing its role in museographic spaces that raise, in a maximum exponent, the potential and exigencies of lighting design. In the late XVIII century, when the museums began to emerge as cultural spreading vehicles, their operation depended on the natural light conditions. In the transition to the XX century, one of the major changes in those spaces resulted from the introduction of electric lighting, whose performance didn\'t stop to improve since then. Today, LED technology surprises us with unprecedented quantitative and qualitative results. In the XXI century, with the current evolution of societies, technologies and global environmental conditions, we are facing a new turning point. In this sense, this research selected five general topics of analysis whose reflection, in our opinion, is decisive to contemporary museum lighting design results. It begins with People, because, first of all, light is an essential element for the human condition and the artificial version is its own invention. It explores the Architecture theme, whose forms are only perceptible under light, resulting in this inseparable relationship. It evaluates the Context, since the local conditions affect any project, even the lighting design one. It continues with Technology, essential for the development of any contemporary intervention. It examines the Artwork, the ultimate focus of a museum-exhibition, par excellence. Finally, some contemporary examples try to illustrate the explored themes. And with the initials of those five themes it comes the word that synthesizes this work: PACTO (in english: PACT). Actually, we believe that the triumph of a museum\'s lighting project will depend on the pact, in other words, the agreement and the harmony between the five crucial elements involved in the process: People, Architecture, Context, Technology and Artwork. Through a methodology supported by the permanent theoretical update with specific bibliography, but mainly through an active participation in international conferences and workshops specialized on this topic, we tried to absorb and here report the most recent discoveries and practical applications of such a dynamic and interdisciplinary element as artificial light. Besides the sustainable and efficient thinking, a 21st century museum must add to the process the challenge of adequately enhance the architecture, rise the art works perception with maximum preservation and, with total sensitivity, make the visitor experience functional and, above all, unforgettable.

CdTe/CdS solar cells have shown great potential for terrestrial solar power applications. To be commercially viable they need to operate efficiently for about 30 years. CdS/CdTe solar cells fabricated at USF have shown record efficiencies upto 16.5% [46]. This research involves the study of thermal stress (TS) and light soaking (LS) on the stability of high efficiency (>10%) solar cells. The change in key electrical parameters Voc, FF, Jsc, A and Jo are quantified for more than 2000 hours of stressing. The device degradation was found to increase with stress temperature for TS. Below 100oC, the changes were due to collection and recombination losses. Above 100oC, "shunting" mechanisms were found to start affecting the device performance. A fast drop in performance within the first 500 hours was observed. It is believed to be due to an increase in deep-level Cu-related defects that increase with stress temperature. Diffusion of Cui+ ions from the back contact along CdTe grain boundaries had been previously reported [16]. An increase in light/dark J-V crossover and bulk Rs with stress time and temperature was observed. A slow degradation component attributed to Cu-related substitutional defect [23] formation/diffusion to the junction and CdS is proposed. This should compensate the CdS over time and increase its photoconductivity/resistivity. An improvement in the current collection and FF within 100 hours of LS was observed. This is possibly due to the enhancement of Cui+ diffusion into the junction and CdS during LS as previously reported [16]. A reduction in light/dark J-V crossover was observed, possibly due to an increase in CdS doping and reduction in the CdS/SnO2 front contact barrier. However, a fast decrease in Voc and increase in recombination current was also observed in the first 1000 hours of LS. This is possibly due to the existence of higher concentration of Cu-related deep level defects at the junction. A larger decrease in Voc was found for LS than TS at the same operating temperature. A continuous drop in performance over time is observed for both TS and LS. The existence of a slow degradation component involving the formation/diffusion of Cu- related substitutional defects at the junction and CdS is proposed. The concentration of this defect is probably not high enough in CdS for LS samples to affect their photoconductivity and cause light/dark J-V crossover in 2000 hours.

Le but du rendu stylisé est de produire un rendud'une scène 3D dans le style visuel particuliervoulu par un artiste.Cela nécessite de reproduire automatiquementsur ordinateur certaines caractéristiquesd'illustrations traditionnelles: par exemple,la façon dont un artiste représente les ombres et lalumière, les contours des objets, ou bien les coupsde pinceau qui ont servi à créer une peinture.Les problématiques du rendu stylisé sont pertinentesdans des domaines comme la réalisation de films d'animation 3Dou le jeu vidéo, où les studios cherchent de plus en plus à se démarquerpar des styles visuels originaux.Dans cette thèse, nous explorons des techniques destylisation qui peuvent s'intégrer dans des pipelinesde rendu temps-réel existants, et nous proposons deux contributions.La première est un outil de création de modèles d'illuminationstylisés pour des objets 3D.La conception de ces modèles est complexe et coûteuse en temps,car ils doivent produire un résultat cohérentsous une multitude d'angles de vue et d'éclairages.Nous proposons une méthode qui facilite la créationde modèles d'illumination pour le rendu stylisé,en les décomposant en sous-modèles plus simples à manipuler.Notre seconde contribution est un pipeline de rendude scènes 3D dans un style peinture,qui utilise une combinaison de bruits procéduraux 3Det de filtrage en espace écran.Des techniques de filtrage d'image ont déjà été proposéespour styliser des images ou des vidéos:le but de ce travail est d'utiliser ces filtres pourstyliser des scènes 3D tout en gardant la cohérence du mouvement.Cependant, directement appliquer un filtreen espace écran produit des défauts visuels au niveau dessilhouettes des objets.Nous proposons une méthode qui permet d'assurer la cohérence du mouvement,en guidant les filtres d'images avec des informations sur la géométrie extraites de G-buffers, et qui élimine les défauts aux silhouettes. / The goal of stylized rendering is to render 3D scenes in the visual style intended by an artist.This often entails reproducing, with some degree of automation,the visual features typically found in 2D illustrationsthat constitute the "style" of an artist.Examples of these features include the depiction of light and shade,the representation of the contours of objects,or the strokes on a canvas that make a painting.This field is relevant today in domains such as computer-generated animation orvideo games, where studios seek to differentiate themselveswith styles that deviate from photorealism.In this thesis, we explore stylization techniques that can be easilyinserted into existing real-time rendering pipelines, and propose two novel techniques in this domain.Our first contribution is a workflow that aims to facilitatethe design of complex stylized shading models for 3D objects.Designing a stylized shading model that follows artistic constraintsand stays consistent under a variety of lightingconditions and viewpoints is a difficult and time-consuming process.Specialized shading models intended for stylization existbut are still limited in the range of appearances and behaviors they can reproduce.We propose a way to build and experiment with complex shading modelsby combining several simple shading behaviors using a layered approach,which allows a more intuitive and efficient exploration of the design space of shading models.In our second contribution, we present a pipeline to render 3D scenes in painterly styles,simulating the appearance of brush strokes,using a combination of procedural noise andlocal image filtering in screen-space.Image filtering techniques can achieve a wide range of stylized effects on 2D pictures and video:our goal is to use those existing filtering techniques to stylize 3D scenes,in a way that is coherent with the underlying animation or camera movement.This is not a trivial process, as naive approaches to filtering in screen-spacecan introduce visual inconsistencies around the silhouette of objects.The proposed method ensures motion coherence by guiding filters with informationfrom G-buffers, and ensures a coherent stylization of silhouettes in a generic way.

There is a tendency in modern times for life to be divided into strictly separated categories-our music is divided into bins at the record store according to sometimes arbitrary genre distinctions, courses offered by one university department often cannot be counted towards a degree in another department, and students from middle school through college are outraged when they learn that "spelling counts" in a history paper. These distinctions, which are second nature to us even in childhood, were not as numerous or as strict in the medieval European understanding of life. Even when there were systems of division, such as the classification of scholarly subjects according to the Trivium and Quadrivium, the classifications were seen as interconnected and were meant to be studied together. I don't believe we can hope to truly understand any aspect of medieval culture if we examine these aspects in isolation according to our own categories. My hope is to come to a greater understanding of some part of medieval culture by examining in combination two aspects of this culture that are not normally combined in modern study-sacred architecture and sacred literature. I will explore correlations in the use of sacred geometry, number symbolism, light metaphysics, and optics in Gothic cathedral architecture and sacred literature of the same period. I will also explore the evolution of cathedral architecture from the Romanesque model to the Gothic model in terms of correlations with an evolving approach to popular theology as reflected in the literature of the period. More specifically, I will look at the use of sacred geometry and number symbolism as a central element of sacred architecture regardless of style and period and the increasing importance of light metaphysics and optics in Gothic architecture as a reflection of a changing approach to popular theology culminating in such thirteenth and fourteenth century writings as those of Robert Grosseteste, Chaucer, and Dante, particularly his Divine Comedy, which present to a popular audience a complex theology which would previously have been reserved for a clerical audience.

Augmented Reality (AR) involves adding virtual content into real scenes. Scenes are viewed using a Head-Mounted Display or other display type. In order to place content into the user's view of a scene, the user's position and orientation relative to the scene, commonly referred to as their pose, must be determined accurately. This allows the objects to be placed in the correct positions and to remain there when the user moves or the scene changes. It is achieved by tracking the user in relation to their environment using a variety of technology. One technology which has proven to provide accurate results is computer vision. Computer vision involves a computer analysing images and achieving an understanding of them. This may be locating objects such as faces in the images, or in the case of AR, determining the pose of the user. One of the ultimate goals of AR systems is to be capable of operating under any condition. For example, a computer vision system must be robust under a range of different scene types, and under unpredictable environmental conditions due to variable illumination and weather. The majority of existing literature tests algorithms under the assumption of ideal or 'normal' imaging conditions. To ensure robustness under as many circumstances as possible it is also important to evaluate the systems under adverse conditions. This thesis seeks to analyse the effects that variable illumination has on computer vision algorithms. To enable this analysis, test data is required to isolate weather and illumination effects, without other factors such as changes in viewpoint that would bias the results. A new dataset is presented which also allows controlled viewpoint differences in the presence of weather and illumination changes. This is achieved by capturing video from a camera undergoing a repeatable motion sequence. Ground truth data is stored per frame allowing images from the same position under differing environmental conditions, to be easily extracted from the videos. An in depth analysis of six detection algorithms and five matching techniques demonstrates the impact that non-uniform illumination changes can have on vision algorithms. Specifically, shadows can degrade performance and reduce confidence in the system, decrease reliability, or even completely prevent successful operation. An investigation into approaches to improve performance yields techniques that can help reduce the impact of shadows. A novel algorithm is presented that merges reference data captured at different times, resulting in reference data with minimal shadow effects. This can significantly improve performance and reliability when operating on images containing shadow effects. These advances improve the robustness of computer vision systems and extend the range of conditions in which they can operate. This can increase the usefulness of the algorithms and the AR systems that employ them.

<p>This thesis explores efficient techniques for high quality real-time rendering of large architectural environments using affordable graphics hardware, as applied to illumination, including window reflections, shadows, and "bump mapping". For each of these fields, the thesis investigates existing methods and intends to provide adequate solutions. The focus lies on the use of new features found in current graphics hardware, making use of new OpenGL extensions and functionality found in Shader Model 3.0 vertex and pixel shaders and the OpenGL 2.0 core. The thesis strives to achieve maximum image quality, while maintaining acceptable performance at an affordable cost.</p><p>The thesis shows the feasibility of using deferred shading on current hardware and applies high dynamic range rendering with the intent to increase realism. Furthermore, the thesis explains how to use environment mapping to simulate true planar reflections as well as incorporates relevant image post-processing effects. Finally, a shadow mapping solution is provided for the future integration of dynamic geometry.</p>

L'utilisation d'algorithmes de vision permettrait d'élargir le domaine d'application des systèmes d'aide à la conduite à d'autres situations telles que : les scènes urbaines ou les conditions météorologiques dégradées. À cette fin, trois nouvelles applications sont étudiées dans cette thèse pour la pluie et les feux tricolores. La pluie est la condition météorologique dégradée la plus fréquente. Nous comparons les modèles physiques et photométriques existants pour la pluie et les gouttes de pluie. Lors d'une conduite en temps de pluie de jour, les gouttes sur le pare-brise diminuent considérablement la visibilité du conducteur. Lorsqu'elles sont vue par une camera embarquée standard celles-ci apparaissent défocalisées. Ainsi, nous proposons de détecter ces gouttes hors-focus en utilisant soit une approche par manque de gradients soit par l'évaluation locale du flou. Lors d'une conduite de nuit sous la pluie, ce sont les phares qui paradoxalement diminuent la visibilité car leur lumière est réfléchie par les gouttes vers le conducteur. Nous appuyant sur la conception d'un simulateur physique, nous proposons un éclairage adaptatif qui illuminerait la scène sans éclairer les gouttes qui tombent. Les résultats de notre simulateur et le premier prototype construit montre que l'idée avancée pourrait efficacement améliorer la visibilité générale d'une scène. D'autre part, nous étudions la détection et le suivi de gouttes de pluie à grande vitesse. Les feux tricolores ont un rôle crucial dans la compréhension des scènes urbaines. Bien qu'il existe déjà des systèmes de détection de feux tricolores, les algorithmes actuels ne fonctionnent que dans des conditions simples. Ainsi, nous avons développé un algorithme de détection de feux tricolores qui utilise une détection en niveau de gris des spots lumineux et une classification par reconnaissance de modèle. L'approche ainsi conçue est assez flexible pour détecter différents types de feux tricolores même avec une camera à faible dynamique. Notre proposition a été évaluée sur des séquences acquises en France, Chine et Suisse.

This thesis project uses various Industrial design methods to create a concept that will evolve a sandbox into a more versatile and interesting playing area. By using parts that can be attached to the frame of the sandbox many different versions can be built to suit different demands and needs. The concept also uses lights and decorated panels to make the sandbox more interesting and visible in today's colorful playgrounds. The project is based on the meaning different stakeholders could have in the product. Research has shown that products made with the help of stakeholders has a better chance to be realized. The findings from research by interviews, fieldtrips and library studies were used as reference when sketching and building sketch-models. Sketching is used both for ideation and for explanatory pictures and has been a big part of the project. Many of the sketches and photos can be seen in the report and in the attachments.