Atmospheric cloud representation methods in computer graphics: A review

Cloud representation is one of the important components in the atmospheric cloud visualization system. Lack of review papers on the cloud representation methods available in the area of computer graphics has directed towards the difficulty for researchers to understand the appropriate solutions. Therefore, this paper aims to provide a comprehensive review of the atmospheric cloud representation methods that have been proposed in the computer graphics domain, involving the classical and the current state-of-the-art approaches. The reviewing process was conducted by searching, selecting, and analyzing the prominent articles collected from online digital libraries and search engines. We highlighted the taxonomic classification of the existing cloud representation methods in solving the atmospheric cloud-related problems. Finally, research issues and directions in the area of cloud representations and visualization have been discussed. This review would be significantly beneficial for researchers to clearly understand the general picture of the existing methods and thus helping them in choosing the best-suited approach for their future research and development

Multiresolution Techniques for Real–Time Visualization of Urban Environments and Terrains

In recent times we are witnessing a steep increase in the availability of data coming from real–life environments. Nowadays, virtually everyone connected to the Internet may have instant access to a tremendous amount of data coming from satellite elevation maps, airborne time-of-flight scanners and digital cameras, street–level photographs and even cadastral maps. As for other, more traditional types of media such as pictures and videos, users of digital exploration softwares expect commodity hardware to exhibit good performance for interactive purposes, regardless of the dataset size. In this thesis we propose novel solutions to the problem of rendering large terrain and urban models on commodity platforms, both for local and remote exploration. Our solutions build on the concept of multiresolution representation, where alternative representations of the same data with different accuracy are used to selectively distribute the computational power, and consequently the visual accuracy, where it is more needed on the base of the user’s point of view. In particular, we will introduce an efficient multiresolution data compression technique for planar and spherical surfaces applied to terrain datasets which is able to handle huge amount of information at a planetary scale. We will also describe a novel data structure for compact storage and rendering of urban entities such as buildings to allow real–time exploration of cityscapes from a remote online repository. Moreover, we will show how recent technologies can be exploited to transparently integrate virtual exploration and general computer graphics techniques with web applications

Towards Predictive Rendering in Virtual Reality

The strive for generating predictive images, i.e., images representing radiometrically correct renditions of reality, has been a longstanding problem in computer graphics. The exactness of such images is extremely important for Virtual Reality applications like Virtual Prototyping, where users need to make decisions impacting large investments based on the simulated images. Unfortunately, generation of predictive imagery is still an unsolved problem due to manifold reasons, especially if real-time restrictions apply. First, existing scenes used for rendering are not modeled accurately enough to create predictive images. Second, even with huge computational efforts existing rendering algorithms are not able to produce radiometrically correct images. Third, current display devices need to convert rendered images into some low-dimensional color space, which prohibits display of radiometrically correct images. Overcoming these limitations is the focus of current state-of-the-art research. This thesis also contributes to this task. First, it briefly introduces the necessary background and identifies the steps required for real-time predictive image generation. Then, existing techniques targeting these steps are presented and their limitations are pointed out. To solve some of the remaining problems, novel techniques are proposed. They cover various steps in the predictive image generation process, ranging from accurate scene modeling over efficient data representation to high-quality, real-time rendering. A special focus of this thesis lays on real-time generation of predictive images using bidirectional texture functions (BTFs), i.e., very accurate representations for spatially varying surface materials. The techniques proposed by this thesis enable efficient handling of BTFs by compressing the huge amount of data contained in this material representation, applying them to geometric surfaces using texture and BTF synthesis techniques, and rendering BTF covered objects in real-time. Further approaches proposed in this thesis target inclusion of real-time global illumination effects or more efficient rendering using novel level-of-detail representations for geometric objects. Finally, this thesis assesses the rendering quality achievable with BTF materials, indicating a significant increase in realism but also confirming the remainder of problems to be solved to achieve truly predictive image generation

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

Authorial Cameos in Post-Romantic Russian Literature

This dissertation examines representations of authorship in Russian literature from a number of perspectives, including the specific Russian cultural context as well as the broader discourses of romanticism, autobiography, and narrative theory. My main focus is a narrative device I call "the figured author," that is, a background character in whom the reader may recognize the author of the work. I analyze the significance of the figured author in the works of several Russian nineteenth- and twentieth- century authors in an attempt to understand the influence of culture and literary tradition on the way Russian writers view and portray authorship and the self. The four chapters of my dissertation analyze the significance of the figured author in the following works: 1) Pushkin's Eugene Onegin and Gogol's Dead Souls; 2) Chekhov's "Ariadna"; 3) Bulgakov's "Morphine"; 4) Nabokov's The Gift. In the Conclusion, I offer brief readings of Kharms's "The Old Woman" and "A Fairy Tale" and Zoshchenko's Youth Restored. One feature in particular stands out when examining these works in the Russian context: from Pushkin to Nabokov and Kharms, the "I" of the figured author gradually recedes further into the margins of narrative, until this figure becomes a third-person presence, a "he." Such a deflation of the authorial "I" can be seen as symptomatic of the heightened self-consciousness of Russian culture, and its literature in particular. By examining figured authors across these works, I explore authorship in Russia as a self-questioning, and potentially self-erasing, practice

Herman Melville and the German Roman

By focusing on Melville\u27s Mardi, Moby-Dick and Pierre, and by studying these works in the context of German romantic irony as defined by Friedrich Schlegel and practiced by Jean Paul Richter, this dissertation offers comparative readings of Melville\u27s work that have not yet been explored. By placing these works in a German rather than a British context, this study hopes to illumine some of the structural qualities and philosophical concerns that angered Melville\u27s contemporary critics and caused their fear that Melville\u27s career had been ruined by his exposure to German literature

Automatic signature verification system

Philosophiae Doctor - PhDIn this thesis, we explore dynamic signature verification systems. Unlike other signature models, we use genuine signatures in this project as they are more appropriate in real world applications. Signature verification systems are typical examples of biometric devices that use physical and behavioral characteristics to verify that a person really is who he or she claims to be. Other popular biometric examples include fingerprint scanners and hand geometry devices. Hand written signatures have been used for some time to endorse financial transactions and legal contracts although little or no verification of signatures is done. This sets it apart from the other biometrics as it is well accepted method of authentication. Until more recently, only hidden Markov models were used for model construction. Ongoing research on signature verification has revealed that more accurate results can be achieved by combining results of multiple models. We also proposed to use combinations of multiple single variate models instead of single multi variate models which are currently being adapted by many systems. Apart from these, the proposed system is an attractive way for making financial transactions more secure and authenticate electronic documents as it can be easily integrated into existing transaction procedures and electronic communication

Human and the animal in Victorian gothic scientific literature

This doctoral thesis examines the role of animals in nineteenth-century science and Victorian Gothic fiction of the latter half of the century. It is interdisciplinary in its exploration of the interrelationship between science writings and literary prose and it seeks to place the Gothic animal body in its cultural and historical setting. This study is interested in the ways in which Gothic literature tests the limits of the human by using scientific ideas about disease, evolution, species confusion, and disability. In analysing the animal trope in Gothic scientific fiction, this thesis conceptualises the ways in which the Gothic mode functions in relation to, while setting itself apart from, contemporary scientific theories about humankind‘s place in the natural world. Chapter 1, 'Man‘s Best Fiend: Evolution, Rabies, and the Gothic Dog‘, focuses on the dog as an animal whose ability to carry and communicate deadly diseases to humans exemplified the breakdown of the animal-human boundary. I read late-nineteenth-century vampire and werewolf narratives as literary manifestations of social hysteria associated with dogs and rabies. In Chapter 2, 'Shaping Evolution: Amphibious Gothic in Edward Bulwer-Lytton‘s The Coming Race and William Hope Hodgson‘s The Boats of the “Glen Carrig”, I examine the role of the frog in Victorian science as the background to Gothic fiction‘s portrayal of the Gothic body as an amphibious being. The next chapter explores the spider‘s function in Victorian natural history as the background to its role as a protean and unstable Gothic trope in fiction. Chapter four, 'Geological Underworlds: Mythologizing the Beast in Victorian Palaeontology‘, looks at ways in which the dinosaur in science influenced the literary imaginations of Gothic writers Arthur Conan Doyle, Arthur Machen, and Bram Stoker. Under the title "Monsters Manufactured!": Humanised Animals, Freak Culture, and the Victorian Gothic‘, the final chapter concludes the study with a discussion of freak culture, making key links between unusually-shaped people in society and human/animal hybrids in the Gothic fiction of H. G. Wells, Richard Marsh, and Wilkie Collins

Belonging and Narrative

Why did the novel become so popular in the past three centuries, and how did the American novel contribute to this trend? As a key provider of the narrative frames and formulas needed by modern individuals to give meaning and mooring to their lives. Drawing on phenomenological hermeneutics, human geography and social psychology, Laura Bieger contends that belonging is not a given; it is continuously produced by narrative. Against the current emphasis on metaphors of movement and destabilization, she explores the salience and significance of home. Challenging views of narrative as a mechanism of ideology, she approaches narrative as a practical component of dwelling in the world - and the novel a primary place-making agent

Keys to The Gift

"Yuri Leving’s Keys to The Gift: A Guide to Vladimir Nabokov’s Novel is a new systematization of the main available data on Nabokov’s most complex Russian novel, The Gift (1934–1939). From notes in Nabokov’s private correspondence to scholarly articles accumulated during the seventy years since the novel’s first appearance in print, this work draws from a broad spectrum of existing material in a succinct and coherent way and provides innovative analyses. The first part of the monograph, “The Novel,” outlines the basic properties of The Gift (plot, characters, style, and motifs) and reconstructs its internal chronology. The second part, “The Text,” describes the creation of the novel and the history of its publication, public and critical reaction, challenges of English translation, and post-Soviet reception. Along with annotations to all five chapters of The Gift, the commentary provides insight into problems of paleography, featuring a unique textological analysis of the novel