One of the main goals of computer graphics is the fast synthesis of photorealistic image of virtual 3D scenes. The work presented in this thesis addresses this goal of speed and realism. In real-time realistic rendering, we encounter certain problems that are difficult to solve in the traditional 3-dimensional geometric space. We show that using an image-space approach can provide effective solutions to these problems. Unlike geometric space algorithms that operate on 3D primitives such as points, edges, and polygons, image-space algorithms operate on 2D snapshot images of the 3D geometric data. Operating in image-space effectively decouples the geometric complexity of the 3D data from the run-time of the rendering algorithm. Other important advantages of image-space algorithms include ease of implementation on modern graphics hardware, and fast computation of approximate solutions to certain lighting calculations. We have applied the image-space approach and developed algorithms for three prominent problems in real-time realistic rendering, namely, representing and lighting large 3D scenes in the context of grass rendering, rendering caustics, which is a complex indirect illumination effect, and subsurface scattering for rendering of translucent objects.

This dissertation considers a subclass of sum-of-ratios fractional combinatorial optimization problems (FCOPs) whose linear versions admit polynomial-time exact algorithms. This topic lies in the intersection of two scarcely researched areas of fractional programming (FP): sum-of-ratios FP and combinatorial FP. Although not extensively researched, the sum-of-ratios problems have a number of important practical applications in manufacturing, administration, transportation, data mining, etc. Since even in such a restricted research domain the problems are numerous, the main focus of this dissertation is a mathematical programming study of the three, probably, most classical FCOPs: Minimum Multiple Ratio Spanning Tree (MMRST), Minimum Multiple Ratio Path (MMRP) and Minimum Multiple Ratio Cycle (MMRC). The first two problems are studied in detail, while for the other one only the theoretical complexity issues are addressed. The dissertation emphasizes developing solution methodologies for the considered family of fractional programs. The main contributions include: (i) worst-case complexity results for the MMRP and MMRC problems; (ii) mixed 0-1 formulations for the MMRST and MMRC problems; (iii) a global optimization approach for the MMRST problem that extends an existing method for the special case of the sum of two ratios; (iv) new polynomially computable bounds on the optimal objective value of the considered class of FCOPs, as well as the feasible region reduction techniques based on these bounds; (v) an efficient heuristic approach; and, (vi) a generic global optimization approach for the considered class of FCOPs. Finally, extensive computational experiments are carried out to benchmark performance of the suggested solution techniques. The results confirm that the suggested global optimization algorithms generally outperform the conventional mixed 0{1 programming technique on larger problem instances. The developed heuristic approach shows the best run time, and delivers near-optimal solutions in most cases.

In this thesis an image-space and geometry hybrid algorithm for portal rendering is con- structed and evaluated in terms of correctness and performance. A number of tests are de ned and out of these three are selected and executed. Based on the results of these tests, the con- clusion is that a hybrid approach to portal rendering is a valid option for increasing the speed without sacri cing the correctness of an image-space portal rendering algorithm.

Numerous movable books, the so-called pop-ups, are being ascribed to Vojtěch Kubašta (7th ofOctober1914-7th ofJuly1992),anartist,whospentmostofhislifeinPrague.Majority of these titles were published out of Czechoslovakia - in other European countries, in the United Kingdom, but also in more distant Iran or Japan. Kubašta had a unique ability of transforming one plain sheet of paper into an elaborate three-dimensional scene just by cutting and folding its surface on the right places. This artistry of the Czechoslovakian illustrator and paper engineer made him famous and successful all over the world except in his home country. His books are being collected and exhibited, but the very personality of the man, who worked even for Walt Disney, is yet to be discovered. This thesis will examine the life and work of Vojtěch Kubašta. The focus of the text will be the form of his movable fairy tales and their impact on the reader. Answering the question, what makes Kubašta's techniques of making pop-ups so unique, will be the main goal of the presented research. key words: Vojtěch Kubašta (1914-1992), visual arts, book culture, illustration, pop-up, popular culture, Artia, Walt Disney, Czechoslovakia 1948-1989

Tensors are of great interest to many applications in engineering and in medical imaging, but a proper analysis and visualization remains challenging. Physics-based visualization of tensor fields has proven to show the main features of symmetric second-order tensor fields, while still displaying the most important information of the data, namely the main directions in medical diffusion tensor data using texture and additional attributes using color-coding, in a continuous representation. Nevertheless, its application and usability remains limited due to its computational expensive and sensitive nature. We introduce a novel approach to compute a fabric-like texture pattern from tensor fields motivated by image-space line integral convolution (LIC). Although, our approach can be applied to arbitrary, non-selfintersecting surfaces, we are focusing on special surfaces following neural fibers in the brain.We employ a multipass rendering approach whose main focus lies on regaining three-dimensionality of the data under user interaction as well as being able to have a seamless transition between local and global structures including a proper visualization of degenerated points.

Desastres naturais sempre fizeram parte da vida dos seres humanos, porém nos últimos anos devido ao crescimento dos grandes centros urbanos, da dificuldade de aplicação e cumprimento de políticas de preservação ambiental e de alterações climáticas crescentes, as catástrofes naturais estão se tornando comuns, e no caso particular deste estudo os danos causados por cheias têm afetado as populações próximas aos leitos hídricos, causando prejuízos materiais, mortes, desaparecimentos, flagelados e desalojados. Para se conhecer melhor o comportamento destes eventos extremos e aumentar a segurança evitando com isto a perda de vidas e minimizando o prejuízo econômico que advém destes desastres, se faz necessário um estudo das possíveis áreas afetadas identificando os locais de risco e quantificando a criticidade de um evento de grande magnitude. Com base em estudos de eventos anteriores, como os registros de grandes enchentes, e utilizando técnicas modernas de posicionamento por GPS (Global Positioning System), processamento digital de imagens geradas por satélites e representação temática do nivelamento geométrico destas cheias, pode-se reproduzir em modelos estes eventos e quantificá-los com uma boa precisão de seus efeitos nos dias atuais. A simulação destes eventos extremos em um modelo de base confiável que, disponibilizado à defesa civil, traz um conhecimento prévio dos possíveis efeitos de uma ocorrência deste tipo, onde poderão ser planejadas rotas de fugas e ações mitigadoras, minimizando perdas de vidas e grandes prejuízos econômicos. Os mesmos modelos servem também de ferramenta de análise de impacto e planejamentos para melhoria do plano diretor de desenvolvimento social, econômico, ambiental e pesquisas na área acadêmica. Os modelos apresentados contemplam apenas uma pequena parte das possibilidades que um trabalho como este viabiliza na área da pesquisa. Os mapas temáticos com as curvas de nível, médias das enchentes registradas, área destinada à preservação ambiental da orla do rio e o mapa das regiões onde o evento extremo de 41 atingiu, ficam disponibilizados para livre utilização. / Natural disasters have always been part of the human lives, but in recent years due to growth of large urban centers, the difficulty of implementation and compliance of environmental preservation policies and increasing climate change, natural disasters are becoming common, and in the particular case of this study the damage caused by floods have affected populations beds near the water resources, causing material damage, deaths, disappearances, flagellates and homeless. To better understand the behavior of these extreme events and increase safety avoiding the lives loss and minimizing the economic losses that arise from these disasters, it is necessary to study the possible affected areas identifying the risk sites and quantifying the criticality of an event of great magnitude. Based on studies of past events, as the records of large floods, and using modern techniques of GPS positioning, digital image processing generated by satellites and thematic representation of capping geometry of these floods, we can play in these models events and quantify them with a good accuracy of its effects today. The simulation of these extreme events in a confident base model that available to bring the civil defense prior knowledge of the possible effects of an event this kind, which may be planned escape routes and mitigating actions minimizing loss of life and large economic losses. The same models also serve as analysis impact tool and planning for improvement of the master plan for social development, economic, environmental and research in the academic area. The models presented cover only a small part of the possibility that a work like this enables on research area. Thematic maps with contour lines, medium flood recorded, for environmental conservation area bordering the river and the map of the regions where the extreme event of 41 hit, are available for free use.

Desastres naturais sempre fizeram parte da vida dos seres humanos, porém nos últimos anos devido ao crescimento dos grandes centros urbanos, da dificuldade de aplicação e cumprimento de políticas de preservação ambiental e de alterações climáticas crescentes, as catástrofes naturais estão se tornando comuns, e no caso particular deste estudo os danos causados por cheias têm afetado as populações próximas aos leitos hídricos, causando prejuízos materiais, mortes, desaparecimentos, flagelados e desalojados. Para se conhecer melhor o comportamento destes eventos extremos e aumentar a segurança evitando com isto a perda de vidas e minimizando o prejuízo econômico que advém destes desastres, se faz necessário um estudo das possíveis áreas afetadas identificando os locais de risco e quantificando a criticidade de um evento de grande magnitude. Com base em estudos de eventos anteriores, como os registros de grandes enchentes, e utilizando técnicas modernas de posicionamento por GPS (Global Positioning System), processamento digital de imagens geradas por satélites e representação temática do nivelamento geométrico destas cheias, pode-se reproduzir em modelos estes eventos e quantificá-los com uma boa precisão de seus efeitos nos dias atuais. A simulação destes eventos extremos em um modelo de base confiável que, disponibilizado à defesa civil, traz um conhecimento prévio dos possíveis efeitos de uma ocorrência deste tipo, onde poderão ser planejadas rotas de fugas e ações mitigadoras, minimizando perdas de vidas e grandes prejuízos econômicos. Os mesmos modelos servem também de ferramenta de análise de impacto e planejamentos para melhoria do plano diretor de desenvolvimento social, econômico, ambiental e pesquisas na área acadêmica. Os modelos apresentados contemplam apenas uma pequena parte das possibilidades que um trabalho como este viabiliza na área da pesquisa. Os mapas temáticos com as curvas de nível, médias das enchentes registradas, área destinada à preservação ambiental da orla do rio e o mapa das regiões onde o evento extremo de 41 atingiu, ficam disponibilizados para livre utilização. / Natural disasters have always been part of the human lives, but in recent years due to growth of large urban centers, the difficulty of implementation and compliance of environmental preservation policies and increasing climate change, natural disasters are becoming common, and in the particular case of this study the damage caused by floods have affected populations beds near the water resources, causing material damage, deaths, disappearances, flagellates and homeless. To better understand the behavior of these extreme events and increase safety avoiding the lives loss and minimizing the economic losses that arise from these disasters, it is necessary to study the possible affected areas identifying the risk sites and quantifying the criticality of an event of great magnitude. Based on studies of past events, as the records of large floods, and using modern techniques of GPS positioning, digital image processing generated by satellites and thematic representation of capping geometry of these floods, we can play in these models events and quantify them with a good accuracy of its effects today. The simulation of these extreme events in a confident base model that available to bring the civil defense prior knowledge of the possible effects of an event this kind, which may be planned escape routes and mitigating actions minimizing loss of life and large economic losses. The same models also serve as analysis impact tool and planning for improvement of the master plan for social development, economic, environmental and research in the academic area. The models presented cover only a small part of the possibility that a work like this enables on research area. Thematic maps with contour lines, medium flood recorded, for environmental conservation area bordering the river and the map of the regions where the extreme event of 41 hit, are available for free use.

Desastres naturais sempre fizeram parte da vida dos seres humanos, porém nos últimos anos devido ao crescimento dos grandes centros urbanos, da dificuldade de aplicação e cumprimento de políticas de preservação ambiental e de alterações climáticas crescentes, as catástrofes naturais estão se tornando comuns, e no caso particular deste estudo os danos causados por cheias têm afetado as populações próximas aos leitos hídricos, causando prejuízos materiais, mortes, desaparecimentos, flagelados e desalojados. Para se conhecer melhor o comportamento destes eventos extremos e aumentar a segurança evitando com isto a perda de vidas e minimizando o prejuízo econômico que advém destes desastres, se faz necessário um estudo das possíveis áreas afetadas identificando os locais de risco e quantificando a criticidade de um evento de grande magnitude. Com base em estudos de eventos anteriores, como os registros de grandes enchentes, e utilizando técnicas modernas de posicionamento por GPS (Global Positioning System), processamento digital de imagens geradas por satélites e representação temática do nivelamento geométrico destas cheias, pode-se reproduzir em modelos estes eventos e quantificá-los com uma boa precisão de seus efeitos nos dias atuais. A simulação destes eventos extremos em um modelo de base confiável que, disponibilizado à defesa civil, traz um conhecimento prévio dos possíveis efeitos de uma ocorrência deste tipo, onde poderão ser planejadas rotas de fugas e ações mitigadoras, minimizando perdas de vidas e grandes prejuízos econômicos. Os mesmos modelos servem também de ferramenta de análise de impacto e planejamentos para melhoria do plano diretor de desenvolvimento social, econômico, ambiental e pesquisas na área acadêmica. Os modelos apresentados contemplam apenas uma pequena parte das possibilidades que um trabalho como este viabiliza na área da pesquisa. Os mapas temáticos com as curvas de nível, médias das enchentes registradas, área destinada à preservação ambiental da orla do rio e o mapa das regiões onde o evento extremo de 41 atingiu, ficam disponibilizados para livre utilização. / Natural disasters have always been part of the human lives, but in recent years due to growth of large urban centers, the difficulty of implementation and compliance of environmental preservation policies and increasing climate change, natural disasters are becoming common, and in the particular case of this study the damage caused by floods have affected populations beds near the water resources, causing material damage, deaths, disappearances, flagellates and homeless. To better understand the behavior of these extreme events and increase safety avoiding the lives loss and minimizing the economic losses that arise from these disasters, it is necessary to study the possible affected areas identifying the risk sites and quantifying the criticality of an event of great magnitude. Based on studies of past events, as the records of large floods, and using modern techniques of GPS positioning, digital image processing generated by satellites and thematic representation of capping geometry of these floods, we can play in these models events and quantify them with a good accuracy of its effects today. The simulation of these extreme events in a confident base model that available to bring the civil defense prior knowledge of the possible effects of an event this kind, which may be planned escape routes and mitigating actions minimizing loss of life and large economic losses. The same models also serve as analysis impact tool and planning for improvement of the master plan for social development, economic, environmental and research in the academic area. The models presented cover only a small part of the possibility that a work like this enables on research area. Thematic maps with contour lines, medium flood recorded, for environmental conservation area bordering the river and the map of the regions where the extreme event of 41 hit, are available for free use.

The problem of accurately simulating light transport using Monte Carlo integration can be very difficult. In particular, scenes with complex illumination effects or complex materials can cause a scene to converge very slowly and demand a lot of computational time. To overcome this problem, image denoising algorithms have become popular in recent years. In this work we first review known approaches to denoising and adaptive rendering. We implement one of the promising algorithm by Moon et al. [2014] in a commercial rendering system Corona Standalone Renderer, evaluate its performance, strengths and weaknesses on 14 test scenes. These include difficult to denoise and converge rendering effects such as fine sub-pixel geometry, participating media, extreme depth of field of highlights, motion blur, and others. We propose corrections which make the algorithm more stable and robust. We show that it is possible to denoise renderings with Linear Weighted Regression only using a CPU. However, still even after our propositions, it is not possible to filter scenes in a consistent manner without over-blurring or not filtering where desired.

In modern supercomputer architectures, the I/O capabilities do not keep up with the computational speed. Image-based techniques are one very promising approach to a scalable output format for visual analysis, in which a reduced output that corresponds to the visible state of the simulation is rendered in-situ and stored to disk. These techniques can support interactive exploration of the data through image compositing and other methods, but automatic methods of highlighting data and reducing clutter can make these methods more effective. In this paper, we suggest a method of assisted exploration through the combination of feature-centric analysis with image space techniques and show how the reduction of the data to features of interest reduces occlusion in the output for a set of example applications.