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[pt] A visualização volumétrica é uma técnica amplamente utilizada para visualizar dados escalares tridimensionais. Para melhorar a percepção de profundidade e forma, diversas técnicas de iluminação foram propostas, adicionando diferentes tipos de efeitos. Neste trabalho, foi explorada uma nova estratégia para calcular oclusão de ambiente direcional e sombras para volume ray casting. Ela consiste em avaliar a oclusão de um traçado de cone atraves de integrais Gaussianas posicionadas de maneira discreta ao longo do eixo do cone. O valor resultado é utilizado para adicionar oclusão de ambiente direcional e sombras. A partir dos coeficientes de extinção dados pela função de transferência, um volume extra é gerado computando amplitudes representativas de distribuições Gaussianas. O Mipmapping também é utilizado para avaliar de maneira efetiva integrais Gaussianas em diferentes tamanhos posicionadas ao longo do eixo principal do cone, adaptando uma estratégia de circle packing in a circle. Nos resultados, é demonstrado que o método proposto obteve um melhor balanço entre performance e qualidade, comparado com trabalhos propostos anteriormente, com a vantagem de combinar oclusão de ambiente direcional e sombras utilizando o mesmo framework. Em seguida, exploramos três estratégias de visualização volumétrica para reservatórios de petróleo, representados por malhas irregulares contendo distorções geométricas e descontinuidades. Estes algoritmos foram implementados a partir de uma representação compacta que guarda o modelo em GPU. Testes comparativos de performance e qualidade foram feitos utilizando diferentes modelos de reservatório. Por fim, investigamos o ganho de percepção ao adicionar a nossa proposta de oclusão de ambiente direcional. Os algoritmos foram todos implementados utilizando programação de shaders para capacitar a geração de visualizações interativas. / [en] Volume rendering is a widely used technique to visualize 3D scalar data. To enhance visual shape and depth perception, distinct illumination techniques have been proposed, adding different types of lighting effects. In this thesis, we explore a new strategy to compute directional ambient occlusion and shadows for volume ray casting. Our algorithm computes occlusion of traced cones by evaluating Gaussian integrals at discrete samples along the cone axis. The computed occlusion is then used to add directional ambient occlusion effects and to generate shadows. Given the extinction coefficient data volume, we create one extra volume computing representative amplitudes of Gaussian functions. Mipmapping is then used to effectively evaluate Gaussian integrals with different sizes placed along the cone axis, adapting a circle packing approach. We demonstrate that the proposed method delivers a better balance between quality results and performance when compared to previous specialized procedures, with the advantage of combining directional ambient occlusion and shadow generation under the same framework. We also explore three volume rendering algorithms for black oil reservoir models, represented by irregular hexahedral meshes with geometry distortions and discontinuities. These algorithms were implemented under a compact representation that stores the model in the GPU. We compare performance and image quality delivered by each strategy by running a set of experiments with different models. We then investigate the gain in perception when applying our technique to compute directional ambient occlusion effects. The algorithms were entirely implemented on graphics card to produce interactive visualizations.

Wireless transmission is an everyday part of movie production and a tool many people use in their work. Work, on a movie production, is fast, intense, and varies in geographical location almost on a daily basis (sometimes several locations in a day). Despite this, the stream, the transmission, must hold so the crew can work. This thesis explores the different impacts materials have on the transmission (using the Boxx Atom System as a test object). The materials were everyday occurrences such as walls (wood and stone), doors (steel, wood), windows (glass), and humans (the crew). The tests were done in the office of Video Assist Sweden in Stockholm, testing both quality and calculating the link margin. The results gave room for improvement but were interesting and sometimes surprising. Glass is best for a smooth transmission. Wooden doors and human beings’ impact were basically the same and stone and steel had the largest impact. In this thesis, we attempt to explain the results and draw conclusions from them and our own experiences in the field. / Trådlös överföring är en vardaglig del av en filmproduktion och ett verktyg som många använder i sitt arbete. Arbetet med en filmproduktion är snabbt, intensivt och varierar mellan olika platser nästan dagligen (ibland flera platser på en dag). Trots detta måste video transmissionen fungera så att hela teamet kan arbeta effektivt. Detta examensarbete undersöker de olika effekterna material har på transmissionen (med hjälp av Boxx Atom System som testobjekt). Materialen var vardagliga händelser som väggar (trä och sten), dörrar (stål, trä), fönster (glas) och människor (besättningen). Testerna gjordes på Video Assist Swedens kontor i Stockholm, där man testade både kvalitet och beräknade länk-marginalen. Resultaten gav utrymme för förbättringar men var intressanta och ibland överraskande. Glas är bäst för en smidig överföring. Träs och människors påverkan var i princip densamma och sten och stål hade störst påverkan. I detta examensarbete försöker vi förklara resultaten och dra slutsatser från dem och våra egna erfarenheter inom området.

Thesis (MPhil)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: In this thesis, 'shadow' is investigated as an object of thought and (analogically connected to this) of perception. This dialectical process is structured through means of a series of experiments and Plato's allegory of the cave, which is interpreted as a process directed towards selfconciousness. This process is further explained through thinkers such as, Blumenberg, Heidegger, Levinas en Voegelin. The purpose of this study is to break with the self-evident way in which 'shadow' is 'normally' treated and to bring back about a sense of astonishment for it. / AFRIKAANSE OPSOMMING: In hierdie tesis word die 'skaduwee' as waarnemingsobjek en (analogies verwant daaraan) as denkobjek ondersoek. Hierdie dialektiese proses word gestruktureerd met behulp van 'n aantal eksperimente en Plato se grotgelykenis, wat geinterpreteer word as programmaties van die proses van selfbewuswording. Hierdie proses word verder toegelig aan die hand van denkers soos Blumenberg, Heidegger, Levinas en Voegelin. Die doel van die ondersoek is om die vanselfsprekendheid waarmee daar met die fenomeen van die skaduwee omgegaan word te deurbreek en weer verwondering daarvoor op te roep. / NEDERLANDSTALIGE SAMENVATTING: In deze thesis wordt de 'schaduw' als waarnemingsobject en (analogisch verwant daaraan) als denkobject onderzocht. Dit dialectische proces wordt gestructureerd met behulp van een aantal experimenten en Plato's grotvergelijking, die geïnterpreteerd worden als een proces gericht op zeltbewustwording. Dit proces wordt verder toegelicht aan de hand van denkers zoals, Blumenberg, Heidegger, Levinas en Voegelin. Het doel van het onderzoek is om de vanzelfsprekendheid waarmee met het fenomeen van de 'schaduw' omgegaan wordt, te doorbreken en er opnieuw verwondering voor op te roepen.

This thesis discusses two different methods for creating soft shadows. Shadow volumes and shadow mapping, more accurately Variance Soft Shadow Mapping. It presents theory for these shadow algorithms as well as theory for few others which are necessary for understanding. Further it describes how to implement these methods and evaluates these implementations. Shadow volumes are based on creating additional geometry to the scene which serves for specifying region of penumbra. VSSM algorithm is a improved version of classic shadow mapping.

The aim of the master's thesis is to create a graphic intro with the limited size of 64kB. Brief history of a demoscene and the graphics library OpenGL is introduced in the following text. The main part of the work is a description of minimal graphics techniques used in a creative process and their further application in the final programme.

This thesis is concerned in the method of realistic rendering using a distributed raytracing. This method simulates various visual effects and generates high realistic 2D images. The work analyses the problem and explains principles of solution related to this technique. There is also descriprion of the method of simple reytracing which provides a basis for the distributed raytracing. A part of work is specialized for optimalization of distributed raytracing.

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Both Temple and Tomb is a dissertation in two parts. The first part is an examination and analysis of a collection of 'colonial' sculptures on permanent display in the Royal Museum of Central Africa in Tervuren Belgium. The second part is a reflection on the author's own paintings, drawings and film and an examination of the critical potential of these images in challenging the colonial narratives of the RMCA. Part I presents two arguments. The first is that European aesthetic codes have been used to legitimize the conquest of the Congo and to award sanction to a voyeuristic gaze. The second is that the organization of the sculptures of Africans (and European females) into carefully managed spaces and relationships results in the creation of erotically-charged formations that are intended to afford pleasure to male European spectators. Part II examines the strategies used in Re-Turning the Shadows to disrupt (neo)colonial patterns of viewing that have become ritual and 'naturalized'. Against RMCA narratives that pay homage to the objectivity of science and research, the paintings and film present images that explore multiple subjectivities, mythologizing impulses, and metaphoric allusions. / Art History, Visual Arts & Musicology / M.A. (Visual Arts)

Both Temple and Tomb is a dissertation in two parts. The first part is an examination and analysis of a collection of 'colonial' sculptures on permanent display in the Royal Museum of Central Africa in Tervuren Belgium. The second part is a reflection on the author's own paintings, drawings and film and an examination of the critical potential of these images in challenging the colonial narratives of the RMCA. Part I presents two arguments. The first is that European aesthetic codes have been used to legitimize the conquest of the Congo and to award sanction to a voyeuristic gaze. The second is that the organization of the sculptures of Africans (and European females) into carefully managed spaces and relationships results in the creation of erotically-charged formations that are intended to afford pleasure to male European spectators. Part II examines the strategies used in Re-Turning the Shadows to disrupt (neo)colonial patterns of viewing that have become ritual and 'naturalized'. Against RMCA narratives that pay homage to the objectivity of science and research, the paintings and film present images that explore multiple subjectivities, mythologizing impulses, and metaphoric allusions. / Art History, Visual Arts and Musicology / M.A. (Visual Arts)