Les artistes traditionnels peignent directement sur une toile et créent des apparences plausibles de scènes qui ressemblent au monde réel. A l’opposé, les artistes en informatique graphique définissent des objets dans une scène virtuelle (maillages 3D, matériaux et sources de lumière), et utilisent des algorithmes complexes (rendu) pour reproduire leur apparence. D’un côté, les techniques de peinture permettent de librement définir l’apparence. D’un autre côté, les techniques de rendu permettent de modifier séparément et dynamiquement les différents éléments qui définissent l’apparence. Dans cette thèse, nous présentons une approche intermédiaire pour manipuler l’apparence, qui permettent certaines manipulations en 3D en travaillant dans l’espace 2D. Mous étudions d’abord l’impact sur l’ombrage des matériaux, tenant en compte des matériaux comme des filtres passe-bande d’éclairage. Nous présentons ensuite un petit ensemble de relations statistiques locales entre les matériaux / l’éclairage et l’ombrage. Ces relations sont utilisées pour imiter les modifications sur le matériaux ou l’éclairage d’une image d’une sphère créée par un artiste. Les techniques connues sons le nom de LitSpheres / MatCaps utilisent ce genre d’images pour transférer leur apparence `a des objets de forme quelconque. Notre technique prouve la possibilité d’imiter les modifications 3D de la lumière et de matériaux à partir d’une image en 2D. Nous présentons une technique différente pour modifier le troisième élément impliqué dans l’aspect visuel d’un objet, sa géométrie. Dans ce cas, on utilise des rendus comme images d’entrée avec des images auxiliaires qui contiennent des informations 3D de la scène. Nous récupérons un ombrage indépendant de la géométrie pour chaque surface, ce qui nous demande de supposer qu’il n’y a pas de variations spatiales d’éclairage pour chaque surface. L’ombrage récupéré peut être utilisé pour modifier arbitrairement la forme locale de l’objet de manière interactive sans la nécessité de rendre `a nouveau la scène. / Traditional artists paint directly on a canvas and create plausible appearances of real-world scenes. In contrast, Computer Graphics artists define objects on a virtual scene (3D meshes, materials and light sources), and use complex algorithms (rendering) to reproduce their appearance. On the one hand, painting techniques permit to freely define appearance. On the other hand, rendering techniques permit to modify separately and dynamically the different elements that compose the scene. In this thesis we present a middle-ground approach to manipulate appearance. We offer 3D-like manipulation abilities while working on the 2D space. We first study the impact on shading of materials as band-pass filters of lighting. We present a small set of local statistical relationships between material/lighting and shading. These relationships are used to mimic modifications on material or lighting from an artist-created image of a sphere. Techniques known as LitSpheres/MatCaps use these kinds of images to transfer their appearance to arbitrary-shaped objects. Our technique proves the possibility to mimic 3D-like modifications of light and material from an input artwork in 2D. We present a different technique to modify the third element involved on the visual appearance of an object: its geometry. In this case we use as input rendered images alongside with 3D information of the scene output in so-called auxiliary buffers. We are able to recover geometry-independent shading for each object surface, assuming no spatial variations for each recovered surface. The recovered shading can be used to modify arbitrarily the local shape of the object interactively without the need to re-render the scene.

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Nous introduisons un algorithme de décomposition intrinsèque multi-vue qui permet de ré-éclairer une scène extérieure en utilisant quelques images en entrée. Plusieurs applications comme l’architecture, jeux et films exigent de manipuler un modèle 3D d’une scène. Cependant, la modification de telles scènes est limitée par les conditions d’éclairage de capture. Notre méthode estime les images intrinsèques prises dans des conditions d’éclairage identiques avec des ombres. Nous utilisons conjointement une reconstruction 3D automatique et la direction du soleil pour obtenir la décomposition de chaque image en calques de réflectance et d’éclairage malgré l’inexactitude des données du modèle 3D. Notre approche est basée sur deux idées principales. Tout d’abord, nous raffinons l’estimation des paramètres de notre modèle de formation d’image en combinant la simulation d’éclairage 3D avec des méthodes d’optimisation basée image. Deuxièmement, nous utilisons ce modèle pour exprimer la réflectance en fonction de valeur de visibilité discrète pour l’ombre et la lumière, ce qui nous permet d’introduire un classificateur d’ombre robuste pour des paires de points dans une scène. Nos calques intrinsèques sont de qualité suffisante pour manipuler les images d’entrée. Nous déplaçons les ombres portées en créant une géométrie qui préserve les silhouettes d’ombre. Notre méthode est compatible avec les approches de rendu basé image et réduit les coûts de création de contenu 3D. Enfin, nous présentons une étude sur les limites du modèle de réflectance diffus et la difficulté d’appliquer les approches existantes dans le cadre de reconstruction 3D multi vue où les données sont imprécises. / We present a multi-view intrinsic decomposition algorithm that allows relighting of an outdoor scene using just a few photographs as input. Several applications such as architecture, games and movies require a 3D model of a scene. However, editing such scenes is limited by the lighting condition at the time of capture. Our method computes intrinsic images photos taken under the same lighting condition with existing cast shadows by the sun. We use an automatic 3D reconstruction from these photos and the sun direction as input and decompose each image into reflectance and shading layers, despite the inaccuracies and missing data of the 3D model. Our approach is based on two key ideas. First, we progressively improve the accuracy of the parameters of our image formation model by performing iterative estimation and combining 3D lighting simulation with 2D image optimization methods. Second we use the image formation model to express reflectance as a function of discrete visibility values for shadow and light, which allows us to introduce a robust shadow classifier for pairs of points in a scene. Our multi-view intrinsic decomposition is of sufficient quality for relighting of the input images. We create shadow-caster geometry which preserves shadow silhouettes and using the intrinsic layers, we can perform multi-view relighting with moving cast shadows. Our method allows image-based rendering with changing illumination conditions and reduces the cost of creating 3D content for applications. Finally, we present an initial study on the limitation of diffuse reflectance models for these computations.

Made available in DSpace on 2016-01-26T18:56:30Z (GMT). No. of bitstreams: 1 Edson Kiyoharu Hirata.pdf: 924963 bytes, checksum: 902ffb9a22bf446a1e62f646a3763a7d (MD5) Previous issue date: 2014-03-26 / Despite producing best in mild temperatures, the rocket has been cultivated throughout the year in various regions. In tropical areas, the use of photoconversor screens of different shading levels modify the intensity of solar radiation and the spectrum of light on the crops , also changing the temperature of the environment . The aim of this study was to evaluate the physiological responses of the rocket under photoconversor screens during the winter and summer in tropical climate region in São Paulo state. The impact of this technology on productivity and anatomy was evaluated. The field experiment was conducted in randomized block design with four replications. The rocket was grown in beds covered on the top and sides with the screens red, blue, black and thermo-reflective. Additionally the treatment in full sun was evaluated. The response curve to light, chlorophyll fluorescence, chlorophyll content, adaxial and abaxial epidermis, palisade and spongy, stomatal density and venation were evaluated. The evaluation of fresh and dry biomass and productivity was performed when the rocket reached 450 degree day. The results showed that photoconversor screens distinctly modify the environment during the winter and summer, but do not cause significant changes in the photosynthetic process of plants in different screens colors and seasons studied, as well as the density of epidermal cells. In all treatments the spongy parenchyma was higher than palisade parenchyma in the summer, the reverse occurred in winter. Changes in the intensity and spectrum of light as well as the temperature provided superior performance of red screens, with higher values of height and leaf area in the winter and of the thermo-reflective screens in the summer. / Apesar de produzir melhor em temperaturas amenas, a rúcula tem sido semeada ao longo do ano em várias regiões. Em áreas tropicais, o uso de telas coloridas de diferentes níveis de sombreamento modificam a intensidade da radiação solar e o espectro de luz que incide nas culturas, o que altera também a temperatura do ambiente. O objetivo desse trabalho foi avaliar as respostas fisiológicas da rúcula cultivada sob telas fotoconversoras no inverno e verão em região de clima tropical no Estado de São Paulo e o impacto dessa tecnologia sobre a produtividade e a anatomia da planta. O experimento foi conduzido a campo no delineamento em blocos ao acaso com quatro repetições. A rúcula foi cultivada em canteiros cobertos na parte superior e laterais pelas telas vermelha, azul, preta e Aluminet® e adicionalmente foi avaliada a testemunha a pleno sol. Foram realizadas avaliações quanto à curva de resposta à luz, fluorescência da clorofila a , teor de clorofila, epiderme adaxial e abaxial, parênquima paliçádico e esponjoso, densidade estomática e de venação. A avaliação de biomassa fresca e seca e determinação de produtividade foi realizada quando a cultura atingiu 450 graus dia. Os resultados evidenciam que as telas fotoconversoras modificam o ambiente distintamente no inverno e no verão, porém não provocam alteração significativa no processo fotossintético das plantas nas diferentes cores de tela e épocas estudadas, assim como na densidade das células epidérmicas. Em todos os tratamentos a espessura do parênquima esponjoso foi superior ao paliçádico no verão, ocorrendo o inverso no inverno. As modificações na intensidade e espectro de luz e da temperatura proporcionaram desempenho superior da tela vermelha, com maiores valores de altura e área foliar no inverno e das telas Aluminet® no verão.

Made available in DSpace on 2016-07-18T17:51:12Z (GMT). No. of bitstreams: 1 Edson Kiyoharu Hirata.pdf: 924963 bytes, checksum: 902ffb9a22bf446a1e62f646a3763a7d (MD5) Previous issue date: 2014-03-26 / Despite producing best in mild temperatures, the rocket has been cultivated throughout the year in various regions. In tropical areas, the use of photoconversor screens of different shading levels modify the intensity of solar radiation and the spectrum of light on the crops , also changing the temperature of the environment . The aim of this study was to evaluate the physiological responses of the rocket under photoconversor screens during the winter and summer in tropical climate region in São Paulo state. The impact of this technology on productivity and anatomy was evaluated. The field experiment was conducted in randomized block design with four replications. The rocket was grown in beds covered on the top and sides with the screens red, blue, black and thermo-reflective. Additionally the treatment in full sun was evaluated. The response curve to light, chlorophyll fluorescence, chlorophyll content, adaxial and abaxial epidermis, palisade and spongy, stomatal density and venation were evaluated. The evaluation of fresh and dry biomass and productivity was performed when the rocket reached 450 degree day. The results showed that photoconversor screens distinctly modify the environment during the winter and summer, but do not cause significant changes in the photosynthetic process of plants in different screens colors and seasons studied, as well as the density of epidermal cells. In all treatments the spongy parenchyma was higher than palisade parenchyma in the summer, the reverse occurred in winter. Changes in the intensity and spectrum of light as well as the temperature provided superior performance of red screens, with higher values of height and leaf area in the winter and of the thermo-reflective screens in the summer. / Apesar de produzir melhor em temperaturas amenas, a rúcula tem sido semeada ao longo do ano em várias regiões. Em áreas tropicais, o uso de telas coloridas de diferentes níveis de sombreamento modificam a intensidade da radiação solar e o espectro de luz que incide nas culturas, o que altera também a temperatura do ambiente. O objetivo desse trabalho foi avaliar as respostas fisiológicas da rúcula cultivada sob telas fotoconversoras no inverno e verão em região de clima tropical no Estado de São Paulo e o impacto dessa tecnologia sobre a produtividade e a anatomia da planta. O experimento foi conduzido a campo no delineamento em blocos ao acaso com quatro repetições. A rúcula foi cultivada em canteiros cobertos na parte superior e laterais pelas telas vermelha, azul, preta e Aluminet® e adicionalmente foi avaliada a testemunha a pleno sol. Foram realizadas avaliações quanto à curva de resposta à luz, fluorescência da clorofila a , teor de clorofila, epiderme adaxial e abaxial, parênquima paliçádico e esponjoso, densidade estomática e de venação. A avaliação de biomassa fresca e seca e determinação de produtividade foi realizada quando a cultura atingiu 450 graus dia. Os resultados evidenciam que as telas fotoconversoras modificam o ambiente distintamente no inverno e no verão, porém não provocam alteração significativa no processo fotossintético das plantas nas diferentes cores de tela e épocas estudadas, assim como na densidade das células epidérmicas. Em todos os tratamentos a espessura do parênquima esponjoso foi superior ao paliçádico no verão, ocorrendo o inverso no inverno. As modificações na intensidade e espectro de luz e da temperatura proporcionaram desempenho superior da tela vermelha, com maiores valores de altura e área foliar no inverno e das telas Aluminet® no verão.

While real-time applications are nowadays routinely used in visualizing large nu- merical simulations and volumes, handling these large-scale datasets requires high-end graphics clusters or supercomputers to process and visualize them. However, not all users have access to powerful clusters. Therefore, it is challenging to come up with a visualization approach that provides insight to large-scale datasets on a single com- puter. Explorable images (EI) is one of the methods that allows users to handle large data on a single workstation. Although it is a view-dependent method, it combines both exploration and modification of visual aspects without re-accessing the original huge data. In this thesis, we propose a novel image-based method that applies the concept of EI in visualizing large flow-field pathlines data. The goal of our work is to provide an optimized image-based method, which scales well with the dataset size. Our approach is based on constructing a per-pixel linked list data structure in which each pixel contains a list of pathlines segments. With this view-dependent method it is possible to filter, color-code and explore large-scale flow data in real-time. In addition, optimization techniques such as early-ray termination and deferred shading are applied, which further improves the performance and scalability of our approach.

With an increase in processing power, more complex simulations have resulted in larger data size, with higher resolution and more variables. Many techniques have been developed to help the user to visualize and analyze data from such simulations. However, dealing with a large amount of multivariate data is challenging, time- consuming and often requires high-end clusters. Consequently, novel visualization techniques are needed to explore such data. Many users would like to visually explore their data and change certain visual aspects without the need to use special clusters or having to load a large amount of data. This is the idea behind explorable images (EI). Explorable images are a novel approach that provides limited interactive visualization without the need to re-render from the original data [40]. In this work, the concept of EI has been used to create a workflow that deals with explorable iso-surfaces for scalar fields in a multivariate, time-varying dataset. As a pre-processing step, a set of iso-values for each scalar field is inferred and extracted from a user-assisted sampling technique in time-parameter space. These iso-values are then used to generate iso- surfaces that are then pre-rendered (from a fixed viewpoint) along with additional buffers (i.e. normals, depth, values of other fields, etc.) to provide a compressed representation of iso-surfaces in the dataset. We present a tool that at run-time allows the user to interactively browse and calculate a combination of iso-surfaces superimposed on each other. The result is the same as calculating multiple iso- surfaces from the original data but without the memory and processing overhead. Our tool also allows the user to change the (scalar) values superimposed on each of the surfaces, modify their color map, and interactively re-light the surfaces. We demonstrate the effectiveness of our approach over a multi-terabyte combustion dataset. We also illustrate the efficiency and accuracy of our technique by comparing our results with those from a more traditional visualization pipeline.

Climate change temperatures expected to rise and extreme heat events (HW) canbe intensified. The influence of climate change on the built environment willbecame more apparent over the coming years. For example, there would be ashift in the risk of overheating in buildings, as well as the cooling and heatingneeds.Studies found that design strategies used to optimize buildings for winter like:good thermal insulation, high airtightness, and extra heat gains increase the riskof overheating. Thus, because of climate change, there is a need for checking thebuildings for summer conditions even in heating dominated countries.This study aims to investigate the potential of two main passive design strategiesto mitigate indoor overheating: ventilation and shading. The main focus of thisstudy is on single-family homes within the Swedish context. Bysjöstrand EkobyAssociation’s Bysjöstrand eco-village project is used as case study. 30 singlefamilyhomes are simulated using Honeybee to run EnergyPlus for calculatingindoor mean air temperature values, extracting the number of hour andpercentages of overheating for each building.Six alternative scenarios were used to evaluate the eco-village. The firststructures were assessed to determine the hours and percentage of time spentoverheating in the present and future situations. The second scenarios, whichinvolved utilizing natural ventilation, was tested to determine if and to what extentit can help to reduce the overheating risk in present and future.A combination of natural ventilation and shading was used for the last scenariosboth for current and future climate.According to the findings, natural ventilation has the greatest influence in reducingoverheating. Combining these two strategies in 2020 and 2070 can lower theaverage percentages of overheating from 17.5 % to 0.6 % and 52.8 % to 12.4%,respectively.The majority of the overheating risk may be addressed using passive strategies,based on the results. More detailed building design is likely be able to eliminateoverheating in single family homes, however, as this study showed it is importantto consider passive strategies from the early stage on the design process.

This thesis focus is on the design and verification of improvements for the RoScan robotic system texture module. RoScan is a robotic scanner for scanning and diagnosing the human body. In this thesis current texturing module of this system is described. Furthermore this thesis describes the theory of light, color and shading in computer graphics. Subsequently, improvments for RoScan texture module are proposed based on the said principles. The last part deals with the implementation of the test script in Matlab and the verification of the functionality of the proposed solution.

The emergence of freeform architecture provides interesting geometric challenges with regards to the design and manufacturing of large-scale structures. To design these architectural structures, we have to consider two types of constraints. First, aesthetic constraints are important because the buildings have to be visually impressive. Sec- ond, functional constraints are important for the performance of a building and its e cient construction. This thesis contributes to the area of architectural geometry. Specifically, we are interested in the geometric rationalization of freeform architec- ture with the goal of combining aesthetic and functional constraints and construction requirements. Aesthetic requirements typically come from designers and architects. To obtain visually pleasing structures, they favor smoothness of the building shape, but also smoothness of the visible patterns on the surface. Functional requirements typically come from the engineers involved in the construction process. For exam- ple, covering freeform structures using planar panels is much cheaper than using non-planar ones. Further, constructed buildings have to be stable and should not collapse. In this thesis, we explore the geometric rationalization of freeform archi- tecture using four specific example problems inspired by real life applications. We achieve our results by developing optimization algorithms and a theoretical study of the underlying geometrical structure of the problems. The four example problems are the following: (1) The design of shading and lighting systems which are torsion-free structures with planar beams based on quad meshes. They satisfy the functionality requirements of preventing light from going inside a building as shad- ing systems or reflecting light into a building as lighting systems. (2) The Design of freeform honeycomb structures that are constructed based on hex-dominant meshes with a planar beam mounted along each edge. The beams intersect without torsion at each node and create identical angles between any two neighbors. (3) The design of polyhedral patterns on freeform surfaces, which are aesthetic designs created by planar panels. (4) The design of space frame structures that are statically-sound and material-e cient structures constructed by connected beams. Rationalization of cross sections of beams aims at minimizing production cost and ensuring force equilibrium as a functional constraint.