Genitourinary cancer refers to the presence of tumours in the genital or urinary organs such as bladder, kidney and prostate. In 2008 the worldwide incidence of bladder cancer was 382,600 with a mortality of 150,282. Radiotherapy is one of the main treatment choices for genitourinary cancer where accurate delineation of the gross tumour volume (GTV) on computed tomography (CT) images is crucial for the success of this treatment. Limited CT resolution and contrast in soft tissue organs make this difficult and has led to significant inter- and intra- clinical variability in defining the extent of the GTV, especially at the junctions of different organs. In addition the introduction of new imaging techniques and modalities has significantly increased the number of the medical images that require contouring. More advanced image processing is required to help reduce contouring variability and assist in handling the increased volume of data. In this thesis image analysis methodologies were used to extract low-level features such as entropy, moment and correlation from radiotherapy planning CT images. These distinctive features were identified and used for defining the GTV and to implement a fully-automatic contouring system. The first key contribution is to demonstrate that second-order statistics from co-occurrence matrices (GTSDM) give higher accuracy in classifying soft tissue regions of interest (ROIs) into GTV and non-GTV. Loadings of the principal components (PCs) of the GTSDM features were found to be consistent over different patients. Exhaustive feature selection suggested that entropies and correlations produced consistently larger areas under receiver operating characteristic (AUROC) curves than first-order features. The second significant contribution is to demonstrate that in the bladder-prostate junction, where the largest inter-clinical variability is observed, the second-order principal entropy from stationery wavelet denoised CT images (DPE) increased the saliency of the bladder prostate junction. As a result thresholding of the DPE produced good agreement between gold standard clinical contours and those produced by this approach with Dice coefficients. The third contribution is to implement a fully automatic and reproducible system for bladder cancer GTV auto-contouring based on classifying second-order statistics. The Dice similarity coefficients (DSCs) were employed to evaluate the automatic contours. It was found that in the mid-range of the bladder the automatic contours are accurate, but in the inferior and superior ends of bladder automatic contours were more likely to have small DSCs with clinical contours, which reconcile with the fact of clinical variability in defining GTVs. A novel male bladder probability atlas was constructed based on the clinical contours and volume estimation from the classification results. Registration of the classification results with this probabilistic atlas consistently increases the DSCs of the inferior slices.

Para criar representações do mundo real, ilustradores utilizam técnicas baseadas em princípios perceptuais para criar efeitos e comunicar informação de maneira eficiente e elegante. Nos últimos anos, essas técnicas têm sido adotadas na computação gráfica para melhorar a visualização de dados científicos. Os ilustradores tradicionais conseguem compor imagens utilizando apenas linhas, gerando representações limpas e simples e com grande poder de comunicar forma. Apesar de alguns trabalhos tentarem reproduzir os efeitos das ilustrações tradicionais com linhas, os princípios perceptuais utilizados pelos artistas ainda não foram bem explorados. Esses princípios são importantes para gerar uma imagem fácil de interpretar, sem ambigüidades e criar efeitos como focos de atenção, sombreamento, noção de profundidade, etc. Este trabalho explora as técnicas utilizadas pelos ilustradores profissionais na criação de visualizações digitais, propondo a adaptação de um método chamado perspective contouring, utilizado para criar focos de atenção em ilustrações baseadas em linhas de contorno. O sistema de ilustração desenvolvido utiliza uma interface baseada em esboço para a definição das regiões de interesse, onde se quer dar ênfase, para determinação de curvas de eixo do modelo e para o desenho de curvas de controle dos atributos das linhas de desenho, como espessura e espaçamento. A título de resultado, são apresentadas comparações de imagens criadas por um ilustrador profissional e imagens criadas pelo sistema desenvolvido. / To create representations of the real world, illustrators use techniques based on perceptual principles to create effects and communicate information in an efficient and elegant manner. In the last years, these techniques have been adopted in computer graphics to improve the visualization of scientific data. Traditional illustrators can compose images using only lines, creating representations that are clean, simple and are suitable to communicate form. Although some works try to reproduce the effects of traditional line illustration, the perceptual principles used by artists are not fully explored. These principles are important to create an image that is easy to interpret and has no ambiguity, and also to create effects like focus of attention, shading, depth perception, etc. In this work, we aim at exploring the techniques used by professional illustrators in the creation of digital visualizations, by proposing the adaptation of a method called perspective contouring, used to create focus of attention in contour lines illustrations. We implemented an illustration system that uses a sketch-based interface to define the regions of interest, where the emphasis is desirable, to create axis curves for the model, and to draw curves that control line attributes like width and spacing. As results, we present a comparison of images by a professional illustrator and images created with the developed system.

Introduction: There is proven therapeutic benefit in bariatric surgery for obese patients. Consequently the National Institute of Clinical Excellence UK has provided referral guidelines for bariatric surgery. Successful bariatric surgery will result in massive weight loss and ptotic skin, which can cause significant functional and psychological problems. As the number of cases of bariatric surgery increases, a corresponding number of massive weight loss patients will require plastic surgery. In this novel field of post massive weight loss surgery there is a lack of understanding of the demographics, physical symptoms and psychological health of this new group of patients. The tools to assess them are few and not validated, the patient pathway is disjointed and there is no consensus on standardised provision. Method: A prospective multicentre, observational study of outcomes in 100 patients undergoing bariatric and post massive weight loss plastic surgery at 2 clinical sites was performed. Each patient followed a standard operating protocol. This included undergoing a semi structured interview, completing five patient-report outcome measures, having anthropometric measurements and clinical photographs taken. Conclusion: This observational study identified key psychosocial themes prevalent in massive weight loss patients, during their weight loss journey. It identified there are no validated patient reported outcome measures available specific to this cohort of patients. This work led to the development of a new validated tool for massive weight loss body contouring.

Para criar representações do mundo real, ilustradores utilizam técnicas baseadas em princípios perceptuais para criar efeitos e comunicar informação de maneira eficiente e elegante. Nos últimos anos, essas técnicas têm sido adotadas na computação gráfica para melhorar a visualização de dados científicos. Os ilustradores tradicionais conseguem compor imagens utilizando apenas linhas, gerando representações limpas e simples e com grande poder de comunicar forma. Apesar de alguns trabalhos tentarem reproduzir os efeitos das ilustrações tradicionais com linhas, os princípios perceptuais utilizados pelos artistas ainda não foram bem explorados. Esses princípios são importantes para gerar uma imagem fácil de interpretar, sem ambigüidades e criar efeitos como focos de atenção, sombreamento, noção de profundidade, etc. Este trabalho explora as técnicas utilizadas pelos ilustradores profissionais na criação de visualizações digitais, propondo a adaptação de um método chamado perspective contouring, utilizado para criar focos de atenção em ilustrações baseadas em linhas de contorno. O sistema de ilustração desenvolvido utiliza uma interface baseada em esboço para a definição das regiões de interesse, onde se quer dar ênfase, para determinação de curvas de eixo do modelo e para o desenho de curvas de controle dos atributos das linhas de desenho, como espessura e espaçamento. A título de resultado, são apresentadas comparações de imagens criadas por um ilustrador profissional e imagens criadas pelo sistema desenvolvido. / To create representations of the real world, illustrators use techniques based on perceptual principles to create effects and communicate information in an efficient and elegant manner. In the last years, these techniques have been adopted in computer graphics to improve the visualization of scientific data. Traditional illustrators can compose images using only lines, creating representations that are clean, simple and are suitable to communicate form. Although some works try to reproduce the effects of traditional line illustration, the perceptual principles used by artists are not fully explored. These principles are important to create an image that is easy to interpret and has no ambiguity, and also to create effects like focus of attention, shading, depth perception, etc. In this work, we aim at exploring the techniques used by professional illustrators in the creation of digital visualizations, by proposing the adaptation of a method called perspective contouring, used to create focus of attention in contour lines illustrations. We implemented an illustration system that uses a sketch-based interface to define the regions of interest, where the emphasis is desirable, to create axis curves for the model, and to draw curves that control line attributes like width and spacing. As results, we present a comparison of images by a professional illustrator and images created with the developed system.

Este trabalho apresenta uma análise dos principais algoritmos de poligonização de isosuperfícies na GPU. O resultado desta análise mostra tanto como a GPU pode ser modificada para oferecer suporte a este tipo de algoritmo quanto como os algoritmos podem ser modificados para se adaptar as características das GPUs atuais. As técnicas usadas em versões de GPU do Marching Cubes são extendidas e uma poligonização com menos artefatos é gerada. São propostas versões paralelas do Dual Contouring e do Macet, algoritmos que melhoram a aproximação e a forma das malhas de triângulos, respectivamente. Ambas técnicas extraem isosuperfícies a partir de grandes volumes de dados em menos de um segundo, superando versões de CPU em até duas ordens de grandeza. As contribuições desse trabalho incluem uma versão orientada a tabelas do Dual Contouring (DC) para grids estruturados. A tabela é utilizada na especificação da topologia dos quadriláteros, que ajuda a implementação e a eficiência de cache em cenários paralelos. A tabela é adequada para a expansão de streams na GPU em ambos geometry shader e Histogram Pyramids. Além disso, nossa versão de aproximação de características das isosuperfícies é mais simples que a Decomposição de Valores Singulares e também que a Decomposição QR. O posicionamento dos vértices não requer uma diagonalização de matrizes. Ao invés disso, usa-se uma simples interpolação trilinear. Afim de avaliar a eficiência das técnicas apresentadas neste trabalho, comparamos nossas técnicas com versões do Marching Cubes na GPU do estado da arte. Também incluímos uma análise detalhada da arquitetura de GPU para a extração de isosuperfícies, usando ferramentas de avaliação de desempenho da indústria. Essa análise apresenta os gargalos das placas gráficas na extração de isosuperfícies e ajuda na avaliação de possíveis soluções para as GPUs das próximas gerações.

Digital holography is a technique for the recording of holograms via CCD/CMOS devices and enables their subsequent numerical reconstruction within computers, thus avoiding the photographic processes that are used in optical holography. This thesis investigates the various techniques which have been developed for digital holography. It develops and successfully demonstrates a number of refinements and additions in order to enhance the performance of the method and extend its applicability. The thesis contributes to both the experimental and numerical analysis aspects of digital holography. Regarding experimental work: the thesis includes a comprehensive review and critique of the experimental arrangements used by other workers and actually implements and investigates a number of these in order to compare performance. Enhancements to these existing methods are proposed, and new methods developed, aimed at addressing some of the perceived short-comings of the method. Regarding the experimental aspects, the thesis specifically develops:• Super-resolution methods, introduced in order to restore the spatial frequencies that are lost or degraded during the hologram recording process, a problem which is caused by the limited resolution of CCD/CMOS devices.• Arrangements for combating problems in digital holography such as: dominance of the zero order term, the twin image problem and excessive speckle noise.• Fibre-based systems linked to tunable lasers, including a comprehensive analysis of the effects of: signal attenuation, noise and laser instability within such systems.• Two-source arrangements for contouring, including investigating the limitations on achievable accuracy with such systems. Regarding the numerical processing, the thesis focuses on three main areas. Firstly, the numerical calculation of the Fresnel-Kirchhoff integral, which is of vital importance in performing the numerical reconstruction of digital holograms. The Fresnel approximation and the convolution approach are the two most common methods used to perform numerical reconstruction. The results produced by these two methods for both simulated holograms and real holograms, created using our experimental systems, are presented and discussed. Secondly, the problems of the zero order term, twin image and speckle noise are tackled from a numerical processing point of view, complementing the experimental attack on these problems. A digital filtering method is proposed for use with reflective macroscopic objects, in order to suppress both the zero-order term and the twin image. Thirdly, for the two-source contouring technique, the following issues have been discussed and thoroughly analysed: the effects of the linear factor, the use of noise reduction filters, different phase unwrapping algorithms, the application of the super-resolution method, and errors in the illumination angle. Practical 3D measurement of a real object, of known geometry, is used as a benchmark for the accuracy improvements achievable via the use of these digital signal processing techniques within the numerical reconstruction stage. The thesis closes by seeking to draw practical conclusions from both the experimental and numerical aspects of the investigation, which it is hoped will be of value to those aiming to use digital holography as a metrology tool.

Este trabalho apresenta uma análise dos principais algoritmos de poligonização de isosuperfícies na GPU. O resultado desta análise mostra tanto como a GPU pode ser modificada para oferecer suporte a este tipo de algoritmo quanto como os algoritmos podem ser modificados para se adaptar as características das GPUs atuais. As técnicas usadas em versões de GPU do Marching Cubes são extendidas e uma poligonização com menos artefatos é gerada. São propostas versões paralelas do Dual Contouring e do Macet, algoritmos que melhoram a aproximação e a forma das malhas de triângulos, respectivamente. Ambas técnicas extraem isosuperfícies a partir de grandes volumes de dados em menos de um segundo, superando versões de CPU em até duas ordens de grandeza. As contribuições desse trabalho incluem uma versão orientada a tabelas do Dual Contouring (DC) para grids estruturados. A tabela é utilizada na especificação da topologia dos quadriláteros, que ajuda a implementação e a eficiência de cache em cenários paralelos. A tabela é adequada para a expansão de streams na GPU em ambos geometry shader e Histogram Pyramids. Além disso, nossa versão de aproximação de características das isosuperfícies é mais simples que a Decomposição de Valores Singulares e também que a Decomposição QR. O posicionamento dos vértices não requer uma diagonalização de matrizes. Ao invés disso, usa-se uma simples interpolação trilinear. Afim de avaliar a eficiência das técnicas apresentadas neste trabalho, comparamos nossas técnicas com versões do Marching Cubes na GPU do estado da arte. Também incluímos uma análise detalhada da arquitetura de GPU para a extração de isosuperfícies, usando ferramentas de avaliação de desempenho da indústria. Essa análise apresenta os gargalos das placas gráficas na extração de isosuperfícies e ajuda na avaliação de possíveis soluções para as GPUs das próximas gerações.

The present study investigates mixed out aerodynamic loss coefficient measurements for a high turning, contoured endwall passage under transonic operating conditions in presence of upstream purge slot and mateface gap. The upstream purge slot represents the gap between stator-rotor interface and the mateface gap simulates the assembly feature between adjacent airfoils in an actual high pressure turbine stage. While the performance of the mateface and upstream slot has been studied for lower Mach number, no studies exist in literature for transonic flow conditions. Experiments were performed at the Virginia Tech's linear, transonic blow down cascade facility. Measurements were carried out at design conditions (isentropic exit Mach number of 0.87, design incidence) without and with coolant blowing. Upstream leakage flow of 1.0% coolant to mainstream mass flow ratio (MFR) was considered with the presence of mateface gap. There was no coolant blowing through the mateface gap itself. Cascade exit pressure measurements were carried out using a 5-hole probe traverse at a plane 1.0Cax downstream of the trailing edge for a planar geometry and two contoured endwalls. Spanwise measurements were performed to complete the entire 2D loss plane from endwall to midspan, which were used to plot pitchwise averaged losses for different span locations and loss contours for the passage. Results reveal significant reduction in aerodynamic losses using the contoured endwalls due to the modification of flow physics compared to a non contoured planar endwall. / Master of Science

[pt] A extração e visualização de isosuperfícies de campos escalares são importantes para inspeções e análises de modelos em diversas áreas. Uma isosuperfície é representada por uma malha de triângulos que aproxima um conjunto de nível do volume de dados. O foco deste trabalho é a extração e visualização de isosuperfícies de modelos de reservatório de petróleo, representados por malhas de hexaedros levemente côncavos. Para uma melhor representação das isosuperfícies, optou-se pela substituição de triângulos planares por superfícies curvas. Para assegurar a extração de superfícies contínuas e suaves, este trabalho propõe o uso de envelopes para determinação das normais. A técnica proposta é implementada em GPU com uso de subdivisão adaptativa das superfícies. / [en] The extraction and visualization of isosurfaces of scalar fields are important for inspections and analysis of models in several areas. An isosurface is represented by a mesh of triangles that approximates a level set of a data volume. The main focus of this work is the extraction and visualization of isosurfaces of black oil reservoir models, represented by hexahedral meshes with slightly concave cells. For a better representation of the isosurfaces, we have opted to replace planar triangles for curved patches. To ensure the extraction of continuous and smooth surfaces, this work proposes the use of envelopes to determine normals. The proposed technique is implemented in GPU with the usage of adaptive subdivision of patches.

Visualizing and manipulating volumetric data is a major component in many areas including anatomical registration in biomedical fields, seismic data analysis in the oil industry, machine part design in computer-aided geometric design, character animation in the movie industry, and fluid simulation. These industries have to meet the demands of the times and be able to make meaningful assertions about the data they generate. The shear size of this data presents many challenges to facilitating realtime interaction. In the recent decade, graphics hardware has become increasingly powerful and more sophisticated which has introduced a new realm of possibilities for processing volumetric data. This thesis focuses on a suite of techniques for viewing and editing volumetric data that efficiently use the processing power of central processing units (CPUs) as well as the large processing power of the graphics hardware (GPUs). This work begins with an algorithm to improve the efficiency of a texture-based volume rendering. We continue with a framework for performing realtime constructive solid geometry (CSG) with complex shapes and smoothing operations on watertight meshes based on a variation of Depth Peeling. We then move to an intuitive technique for deforming volumetric data using a collection of control points. Finally, we apply this technique to image registration of 3-dimensional computed tomography (CT) images used for lung cancel treatment, planning.