<p>It is important for the military to know as much as possible about how easily detected their vehicles are. One way among many used to detect vehicles is the use of radar sensors. The radar reflecting characteristics of military vehicles are therefor often rigorously tested. With measurements and simulations it is possible to calculate likely detection distances to a vehicle from different angles. This process often produces very large data sets that are hard to analyze.</p><p>This thesis discusses and implements a method for visualizing the detection distance data set and also discusses a lot of related issues with a focus on computer graphics.</p><p>The main concept is called spherical displacement and the idea is to visualize the detection distances as a surface with the imagined vehicle in the center point. Detection is likely inside the surface but not on the outside. This concept is the next step from the colored sphere where the colors represent the detection distance which was previously used.</p><p>The thesis project resulted in a visualization tool that uses the new concept and can handle large data sets. The spherical displacement concept is more intuitive and shows detail better than the colored sphere visualization.</p>

It is important for the military to know as much as possible about how easily detected their vehicles are. One way among many used to detect vehicles is the use of radar sensors. The radar reflecting characteristics of military vehicles are therefor often rigorously tested. With measurements and simulations it is possible to calculate likely detection distances to a vehicle from different angles. This process often produces very large data sets that are hard to analyze. This thesis discusses and implements a method for visualizing the detection distance data set and also discusses a lot of related issues with a focus on computer graphics. The main concept is called spherical displacement and the idea is to visualize the detection distances as a surface with the imagined vehicle in the center point. Detection is likely inside the surface but not on the outside. This concept is the next step from the colored sphere where the colors represent the detection distance which was previously used. The thesis project resulted in a visualization tool that uses the new concept and can handle large data sets. The spherical displacement concept is more intuitive and shows detail better than the colored sphere visualization.

[pt] A visualização de horizontes sísmicos constitui uma importante área de conhecimento amplamente aplicada na prospecção de hidrocarbonetos pela indústria do petróleo. Diferentes técnicas são atualmente empregadas na apresentação destas superfícies, sendo usualmente utilizadas as soluções baseadas na geração de malhas poligonais, que se beneficiam da otimização das placas gráficas atuais no desenho de triiângulos. Este trabalho faz uma avaliação do uso da renderização baseada em pontos, no lugar de polígonos, para a visualização de horizontes sísmicos. Para isso as técnicas de cada etapa do processo são avaliadas, levando-se em conta a natureza específica dos dados de interpretação de horizontes em volumes sísmicos e o resultado final esperado para a visualização deste tipo de dados. O algoritmo utilizado baseia-se no método conhecido como Surface Splatting para a renderização dos pontos originais, sendo estudados a estruturação apropriada para os dados a serem visualizados, a técnica para obtenção de normais, a abordagem adequada para o cálculo da iluminação e mecanismos adicionais necessários ao processo. Resultados da aplicação do método em dados reais são, ao final do trabalho, analisados e comparados à renderização tradicional para os horizontes avaliados. / [en] Seismic horizon visualization stands as an important knowledge area used to support exploration on the oil industry. Different techniques currently employed to render this kind of surfaces are usually based on polygonal meshes generation, which benefits from graphics boards optimization on drawing triangles. This work is an evaluation of Point Based rendering techniques to replace polygonal approaches in seismic horizons visualization. To do so, this study revisits each stage of the seismic visualization process. The algorithm adopted here is based on the Surface Splatting with the EWA filter. This work also presents a study on normal evaluation and data structures to store points and normal. Special care is taken in shading techniques. The implementation yielded results that are used to support the evaluation of the Point Based Techniques on real 3D Seismic data. Traditional triangle based rendering is also presented to compare results.

La simulation informatique est un outil incontournable dans les sciences expérimentales. La puissance de calcul croissante des ordinateurs associée au parallélisme et aux avancées dans la modélisation mathématique des phénomènes physiques permet de réaliser virtuellement des expériences de plus en plus complexes. De plus, l'émergence de la programmation GPU a considérablement accru la qualité et la rapidité de l'affichage. Ceci a permis de démocratiser la visualisation sous forme graphique des résultats de simulation. La visualisation scientifique peut être passive : l'utilisateur peut suivre l'évolution de la simulation ou bien observer ses résultats après que le calcul soit terminé. Elle peut aussi être interactive lorsque le chercheur peut agir sur la simulation alors qu'elle se déroule. Créer de telles applications complexes n'est cependant pas à la portée de tout scientifique non informaticien. La programmation par composants est, depuis des années, mise en avant comme une solution à ce problème. Elle consiste à construire des applications en interconnectant des programmes exécutant des tâches élémentaires. Ce mémoire présente un modèle de composants et une méthode de composition d'applications de visualisation scientifique interactive. Elle s'intéresse, en particulier, à la conciliation de deux contraintes majeures dans la coordination de ces applications : la performance et la cohérence. / Computer simulation is an essential tool in experimental sciences. The increasing computing power, parallelism and the advances in the mathematical modeling of physical phenomena allow to virtually run always more complex experiments. In addition, the rise of GPU programming has greatly increased the quality and performance of display. This has allowed to spread the graphical visualization of simulation results. Scientific visualization can be passive: the user can only follow the simulation's progress or observe its results when it is done. It can also be interactive in which case the researcher can act on the simulation while it is running. Creating such complex applications can, however, be tedious for non-computer-scientists. Component-based development is, for years, highlighted as a solution to this problem. It consists in building applications by interconnecting small programs completing elementary tasks. This thesis presents a component model and a method for composing interactive scientific visualization applications. It particularly focuses on the balance between two major constraints of these applications: performance and coherence.

O aumento do poder computacional e conseqüente desenvolvimento das técnicas de simulação numérica, aliados ao avanço tecnológico dos periféricos de medição, fizeram com que muitas áreas de pesquisa, passassem a necessitar de ferramentas gráficas e de auxílio computacional para apoiar o processo de interpretação das informações geradas. A aplicação de técnicas gráficas para ampliar a capacidade de interpretação de dados científicos tem sido denominada visualização em computação científica (ViSC - Visualization in Scientific Computing). Modelos aerodinâmicos construídos no laboratório, foram simulados em software numérico de método dos painéis e submetidos a rotinas desenvolvidas em C++ as quais serviram de superfície para uma ferramenta do tipo biblioteca, de baixo custo, muito utilizada em universidades do mundo todo, chama VTK (Visualization Tool Kit), que possui elementos gráficos para a geração de visualizações de qualquer tipo de dados. Esses códigos em C++ são responsáveis pelos tipos de visualização gerados e principalmente por permitir o uso da ferramenta. As visualizações de distribuição de pressão e isolinhas nas superfícies dos modelos são de suma importância na identificação de problemas aerodinâmicos possibilitando correções e modificações antes mesmo de o modelo ser construído. / The increase of computational power and the technical development of numerical are responsible for the creation of many new areas that use graphics tools and computational aid for the interpretation of the information generated. The application of graphics techniques to increase the capability of scientific interpretation is called ViSC or Visualization in Scientific Computation. Laboratory built freeflight and wind tunnel models were calculated using numerical software and submitted to routines developed in C++ language which produced various types of visualization while using VTK. Visualization of pressure distributions and streamlines on the model surfaces are important for identification of aerodynamic problems and making corrections and modifications possible before the construction of the physical model.

Estruturas de dados volumétricas são de extrema utilidade em várias aplicações, e em particular na área de Visualização Científica. Essas estruturas são úteis em duas etapas do processo de visualização. A primeira é na representação de dados, isto é, de informações associadas aos valores, medidos ou simulados, os quais se deseja visualizar. A outra fase que necessita de uma estrutura de dados é a fase de exploração, ou seja, o modelo criado é usado tanto para exploração interativa quanto para a realização de simulações sobre o mesmo, por exemplo, numa cirurgia virtual. Está em desenvolvimento no ICMC, uma estrutura de dados volumétrica, chamada Singular Half-Face, que tem como característica a modelagem explícita das singularidades presentes no modelo, além de outros elementos topológicos. Este trabalho de mestrado visa testar a viabilidade da estrutura num contexto de visualização em fluxo de dados, incorporando-a à biblioteca gráfica de visualização Visualization ToolKit (VTK), que possui definição extremamente pobre da topologia dos objetos que representa. Adicionando essa nova classe e realizando sobre ela técnicas convencionais de visualização e exploração de dados, é estudada sua capacidade de apoiar todas as fases do processo de visualização. / Volumetric data structures are of extreme utility in various applications, and particularly in the area of Scientific Visualization. These structures are useful in two stages of the visualization process. The first one is in data representation, that is, in the organization of information associated with the values, measured or simulated, to be visualized. The other phase of the visualization data flow that needs a data structure is the exploration phase. It would be useful to have a model designed to be used both for interactive exploration and for simulation in a number of application, for example, in virtual surgery. A volumetric data structure, named Singular Half-Face (SHF) is being developed at the ICMC, that has as its main characteristic the explicit modeling of singularities present in the model, besides other essential topological elements. This dissertation aims at testing the viability of this structure in a context of visualization in data flow, by incorporating it in the Visualization ToolKit (VTK) class library, whose data structures are extremely poor in definition of the topology of the objects that they represent. By adding SHF to this library and carrying out conventional visualization and data exploration on it, we wish to study its support to all the phases of the visualization process.

Geometrical modeling is a crucial aspect of simulations involving manufactured objects. Apart from the pure construction of curves and surfaces, the analysis of their quality is equally important in the design and manufacturing process. In computer-aided simulation, the original freeorm surfaces need to be tessellated into triangulated surfaces before the simulation procedure. To concurrently and interactively visualize the results from both simulation and surface interrogation in a virtual environment, I propose two novel surface interrogation algorithms for triangulated surfaces instead of the traditional freeorm surfaces. The novel algorithms are interactive and immersive versions of two well-established surface interrogation techniques ? reflection lines and generalized focal surfaces. These two algorithms have been designed to overcome some limitations of the traditional approaches and make them available for interactive and immersive applications. For reflection lines, the new algorithm maps the triangulated surface onto the light plane so that the computation of distance between reflection ray and light line in three dimensions can be reduced to computation of intersections between light lines and triangle edges in two dimensions, simplifying the computation. For generalized focal surfaces, the new algorithm estimates curvature by simple computation of the derivatives of a3rd degree triangular Bézier patch on each triangle and removes the requirement for a minimum number of neighbor points and implicit requirements on how the neighbor points are distributed. Proposed future work on real-time rendering of surface interrogation using a texture mapping technique is discussed.

The sweep paradigm for volume rendering has previously been successfully applied with irregular grids. This thesis describes a parallel volume rendering algorithm called PARZSweep for regular grids that utilizes the sweep paradigm. The sweep paradigm is a concept where a plane sweeps the data volume parallel to the viewing direction. As the sweeping proceeds in the increasing order of z, the faces incident on the vertices are projected onto the viewing volume to constitute to the image. The sweeping ensures that all faces are projected in the correct order and the image thus obtained is very accurate in its details. PARZSweep is an extension of a serial algorithm for regular grids called RZSweep. The hypothesis of this research is that a parallel version of RZSweep can be designed and implemented which will utilize multiple processors to reduce rendering times. PARZSweep follows an approach called image-based task scheduling or tiling. This approach divides the image space into tiles and allocates each tile to a processor for individual rendering. The sub images are composite to form a complete final image. PARZSweep uses a shared memory architecture in order to take advantage of inherent cache coherency for faster communication between processor. Experiments were conducted comparing RZSweep and PARZSweep with respect to prerendering times, rendering times and image quality. RZSweep and PARZSweep have approximately the same prerendering costs, produce exactly the same images and PARZSweep substantially reduced rendering times. PARZSweep was evaluated for scalability with respect to the number of tiles and number of processors. Scalability results were disappointing due to uneven data distribution.

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Este trabalho apresenta o Animbs (Animation for MBS), um sistema capaz de visualizar dados gerados por um sistema de simulação de engenharia (SD/FAST) na forma de animações por computador. SD/FAST é um sistema utilizado para o modelamento e a simulação de sistemas mecânicos multicorpos (MBS). O sistema Animbs permite a associação de uma geometria ao MBS sendo simulado e utiliza os dados produzidos pela simulação do SD/FAST para criar uma animação do comportamento do sistema mecânico e, dessa forma, melhorar a análise de dados feita pelos usuários do SD/FAST. / This work presents Animbs (Animation for MBS), a software that enables the visualization of data generated by an engineering simulation system (SD/FAST) in the form of computer animation. SD/FAST is a system for modeling and simulation of multibody systems (MBS). The Animbs system allows the association of a geometry to the MBS being simulated, and uses the data produced by the SD/FAST simulation to create an animated view of the MBS behavior, thus providing support for enhanced data analysis by users of SD/FAST.