330 research outputs found
High-Quality Visualization and Filtering
No full textDie meisten Renderingmethoden in der Visualisierung und Computergraphik konzentrieren sich entweder auf die Bildqualität; und generieren <i>korrekte</i> Bilder mit nicht mehr interaktiven Bildraten; oder opfern die Darstellungsqualität; um interaktive Performance zu erreichen. Andererseits erlaubt es die momentane Entwicklung im Bereich der Graphikhardware zunehmend; die Qualität von Offline Rendering-Ansätzen mit interaktiver Performance zu kombinieren. Um dies auch tatsächlich nutzen zu können; müssen neue und angepasste Algorithmen entwickelt werden; die die spezielle Architektur von Graphikhardware berücksichtigen. Das zentrale Thema dieser Arbeit ist; hohe Renderingqualität mit Echtzeitfähigkeit bei der Visualisierung von diskreten Volumendaten auf regulären dreidimensionalen Gittern zu kombinieren. Ein wesentlicher Teil beschäftigt sich mit dem generellen Filtern von Texturen unabhängig von deren Dimension. Mit Hilfe der Leistungsfähigkeit heutiger PC Graphikhardware werden Algorithmen demonstriert; die einen Qualitätsstandard erreichen; der bislang nur im Offline Rendering möglich war. Eine grundlegende Operation in der Visualisierung und Computergraphik ist die Rekonstruktion einer kontinuierlichen Funktion aus einer diskreten Darstellung mittels Filterung. Diese Arbeit stellt eine Methode zur Filterung mit Hilfe von Graphikhardware vor; die prinzipiell beliebige Faltungskerne auswerten kann. Die Hauptanwendung ist hierbei die Vergrösserung von Texturen direkt während dem Rendern. Darüber hinaus kann sie aber auch mit MIP-mapping zur Texturverkleinerung kombiniert werden. Im Bereich der Volumenvisualisierung stellt diese Arbeit weiters einen Ansatz zur Echtzeitdarstellung von segmentierten Daten vor. Segmentierte Volumendaten haben speziell in medizinischen Anwendungen hohe Bedeutung. Darüber hinaus stellt diese Arbeit Ansätze zum nicht-photorealistischen Rendern mit hoher Qualität vor; die sich besonders gut eignen; um die Aufmerksamkeit des Betrachters auf bestimmte Fokusbereiche zu lenken. Weiters werden Isoflächen mit Hilfe eines Deferred- Shading Ansatzes dargestellt; wobei differentialgeometrische Eigenschaften; wie beispielsweise die Krümmung der Oberfläche; in Echtzeit berechnet und für eine Vielzahl von Effekten verwendet werden können. Wir schliessen aus den erreichten Resultaten; dass es möglich ist; die Lücke zwischen Offline Rendering mit hoher Qualität auf der einen Seite; und Echtzeitrendering auf der anderen Seite; zu schliessen; ohne dabei notwendigerweise die Qualität zu beeinträchtigen. Besonders wichtig ist dies im Bereich des Renderings von Volumendaten; das sehr oft hohe Qualitätsansprüche hat; etwa bei der Darstellung von medizinischen Daten. - Most rendering methods in visualization and computer graphics are focusing either on image quality in order to produce<i> correct</i> images with non-interactive rendering times; or sacrifice quality in order to attain interactive or even real-time performance. However; the current evolution of graphics hardware increasingly allows to combine the quality of off-line rendering approaches with highly interactive performance. In order to do so; new and customized algorithms have to be developed that take the specific structure of graphics hardware architectures into account. The central theme of this thesis is combining high rendering quality with real-time performance in the visualization of sampled volume data given on regular three-dimensional grids. More generally; a large part of this work is concerned with high-quality filtering of texture maps; regardless of their dimension. Harnessing the computational power of consumer graphics hardware available in off-the-shelf personal computers; algorithms that attain a level of quality previously only possible in off-line rendering are introduced. A fundamental operation in visualization and computer graphics is the reconstruction of a continuous function from a sampled representation via filtering. This thesis presents a method for using completely arbitrary convolution filters for high-quality reconstruction exploiting graphics hardware; focusing on real-time magnification of textures during rendering. High-quality filtering in combination with MIP-mapping is also illustrated in order to deal with texture minification. Since texturing is a very fundamental operation in computer graphics and visualization; the resulting quality improvements have a wide variety of applications; including static texture-mapped objects; animated textures; and texture-based volume rendering. The combination of high-quality filtering and all major approaches to hardwareaccelerated volume rendering is demonstrated. In the context of volume rendering; this thesis introduces a framework for high-quality rendering of segmented volume data; i.e.; data with object membership information such as segmented medical data sets. High-quality shading with per-object optical properties such as rendering modes and transfer functions is made possible; while maintaining real-time performance. The presented method is able to filter the boundaries between different objects on-the-fly; which is non-trivial when more than two objects are present; but important for high-quality rendering. Finally; several approaches to high-quality non-photorealistic volume rendering are introduced; a concept that is especially powerful in combination with segmented volume data in order to focus a viewer s attention and separate focus from context regions. High-quality renderings of isosurfaces are obtained from volumetric representations; utilizing the concept of deferred shading and deferred computation of high-quality differential implicit surface properties. These properties include the gradient; the Hessian matrix; and principal curvature magnitudes as well as directions. They allow high-quality shading and a variety of nonphotorealistic effects building on implicit surface curvature. We conclude that it is possible to bridge the gap between traditional high-quality off- line rendering and real-time performance without necessarily sacrificing quality. In an area such as volume rendering that can be very demanding with respect to quality; e.g.; in medical imaging; but whose usefulness increases significantly with higher interactivity; combining both high quality and high performance is especially important.EG Graphics Dissertation Onlin
A quantitative program for Hadwiger's covering conjecture
No full textIn 1957, Hadwiger made a conjecture that every n-dimensional convex body can be covered by 2(n) translates of its interior. Up to now, this conjecture is still open for all n >= 3. In 1933, Borsuk made a conjecture that every n-dimensional bounded set can be divided into n + 1 subsets of smaller diameters. Up to now, this conjecture is open for 4 <= n <= 297. In this article we encode the two conjectures into continuous functions defined on the spaces of convex bodies, propose a four-step program to attack them, and obtain some partial results.Mathematics, AppliedMathematicsSCI(E)2ARTICLE92551-25605
A Novel Framework for Visual Detection and Exploration of Performance Bottlenecks in Organic Photovoltaic Solar Cell Materials
No full textCurrent characterization methods of the so-called Bulk Heterojunction (BHJ), which is the main material of Organic Photovoltaic (OPV) solar cells, are limited to the analysis of global fabrication parameters. This reduces the efficiency of the BHJ design process, since it misses critical information about the local performance bottlenecks in the morphology of the material. In this paper, we propose a novel framework that fills this gap through visual characterization and exploration of local structure-performance correlations. We also propose a formula that correlates the structural features with the performance bottlenecks. Since research into BHJ materials is highly multidisciplinary, our framework enables a visual feedback strategy that allows scientists to build intuition about the best choices of fabrication parameters. We evaluate the usefulness of our proposed system by obtaining new BHJ characterizations. Furthermore, we show that our approach could substantially reduce the turnaround time.This is the pre-peer reviewed version of the following article: Aboulhassan, Amal, Daniel Baum, Olga Wodo, Baskar Ganapathysubramanian, Aram Amassian, and Markus Hadwiger. "A novel framework for visual detection and exploration of performance bottlenecks in organic photovoltaic solar cell materials." In Computer Graphics Forum, vol. 34, no. 3, pp. 401-410. 2015, which has been published in final form at DOI: 10.1111/cgf.12652. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.</p
Case Study of Physiotherapy Treatment of a Patient with total knee replacement
No full textAuthor: Jiří Hadwiger Title: The case study of physioterapeutical treatment of a patient with total knee replacement diagnosis Objective: The objective of this thesis is processing of the case study of the physioterapeutic care of a patient with total knee replacement diagnosis during an internship at ORFM department at ÚVN hospital. Comprehensive theoretical introduction to this subject is also a part of this thesis. Summary: This thesis is divaded into two parts. The first part consists of the theoretical knowledge of the anatomy, kinesiology and biomechanics of the knee joint. Following is the gonarthrosis chapter as the most common indication for the total knee replacement, its ethiology and choices of treatement. At last to present is total knee replacement, its history, surgical procedure and following postoperative rehabilitation. Second part is a case study of the real patient with total knee replacement diagnosis lasting 8 therapeutical units. In the end of the study is comparison of the paatients condition before and after rehabilitation and evaluation of the effect. Key words: knee joint, total knee replacement, gonarthrosis, physical therapy, case stud
Josef Willomitzer (1849 - 1900). Life and Work of German Writing Author from Bohemia.
No full textJosef Willomitzer (1849 - 1900). Life and Work of German Writing Author from Bohemia. The bachelor theses deals with life and work of german writing author from Bohemia, Josef Willomitzer. The work describes as a introduction the social and culture situation in Prague in the end of 19. century. The following chapters concern Willomitzers life and work in context of the historical and political development of Bohemia. The work is based on information available from ressources such as lexicons, newspaper articles and archive ressources. Apart from his life is in this work described also his journalistic activity. In the last part is summarized Willomitzers literary work. The analysis of chosen works which correspond to certain historical topics is also involved. The purpose of this work is to draw up a compact biography of Josef Willomitzer and a summary of his work. Keywords: Josef Willomitzer, humoresque, journalism, Bohemia, German Prague in the end of 19. centur
Josef Willomitzer (1849 - 1900). Life and Work of German Writing Author from Bohemia.
No full textJosef Willomitzer (1849 - 1900). Life and Work of German Writing Author from Bohemia. The bachelor theses deals with life and work of german writing author from Bohemia, Josef Willomitzer. The work describes as a introduction the social and culture situation in Prague in the end of 19. century. The following chapters concern Willomitzers life and work in context of the historical and political development of Bohemia. The work is based on information available from ressources such as lexicons, newspaper articles and archive ressources. Apart from his life is in this work described also his journalistic activity. In the last part is summarized Willomitzers literary work. The analysis of chosen works which correspond to certain historical topics is also involved. The purpose of this work is to draw up a compact biography of Josef Willomitzer and a summary of his work. Keywords: Josef Willomitzer, humoresque, journalism, Bohemia, German Prague in the end of 19. centur
Parallel Methodologies for a Micropolygon Renderer
No full textThis paper compares the performance of three different methodologies for a multi-threaded micropolygon-based renderer. We extend the REYES [AG99] algorithm for multi-threaded rendering, which we call CASCADE. CASCADE processes one bucket per thread, forwarding primitives and micropolygons to other buckets/threads through split and dice operations. ROUND_ROBIN runs N single-threaded versions of CASCADE and a compositor, where primitives are distributed to each thread in a semi-random manner. NO_FORWARD executes split and dice operations, but a primitive that spans multiple buckets is processed independently by different threads and the primitives generated through split and dice operations that project outside the current bucket are discarded. In addition, bucket scheduling is used in this case to ensure that no thread is starved for work. Extensive analysis demonstrates that none of these methodologies are clearly superior to the others under all combinations of primitive size, count, transparency, and parallelism, so, a hybrid algorithm is proposed whose performance characteristics make it the best choice under all but the most pathological casesEurographics Symposium on Parallel Graphics and Visualizatio
Performance Modeling of vl3 Volume Rendering on GPU-Based Clusters
No full textThis paper presents an analytical model for parallel volume rendering of large datasets using GPU-based clusters. The model is focused on the parallel volume rendering and compositing stages and predicts their performance requiring only a few input parameters. We also present vl3, a novel parallel volume rendering framework for visualization of large datasets. Its performance is evaluated on a GPU-based cluster, weak and strong scaling are studied, and model predictions are validated with experimental results on up to 128 GPUs.Eurographics Symposium on Parallel Graphics and Visualizatio
Collaborative High-fidelity Rendering over Peer-to-peer Networks
No full textDue to the computational expense of high-fidelity graphics, parallel and distributed systems have frequently been employed to achieve faster rendering times. The form of distributed computing used, with a few exceptions such as the use of GRID computing, is limited to dedicated clusters available to medium to large organisations. Recently, a number of applications have made use of shared resources in order to alleviate costs of computation. Peer-to-peer computing has arisen as one of the major models for off-loading costs from a centralised computational entity to benefit a number of peers participating in a common activity. This work introduces a peer-to-peer collaborative environment for improving rendering performance for a number of peers where the program state, that is the result of some computation among the participants, is shared. A peer that computes part of this state shares it with the others via a propagation mechanism based on epidemiology. In order to demonstrate this approach, the traditional Irradiance Cache algorithm is extended to account for sharing over a network within the presented collaborative framework introduced. Results, which show an overall speedup with little overheads, are presented for scenes in which a number of peers navigate shared virtual environments.Eurographics Symposium on Parallel Graphics and Visualizatio
Precomputing Sound Scattering for Structured Surfaces
No full textRoom acoustic simulations commonly use simple models for sound scattering on surfaces in the scene. However, the continuing increase of available parallel computing power makes it possible to apply more sophisticated models. We present a method to precompute the distribution of the reflected sound off a structured surface described by a height map and normal map using the Kirchhoff approximation. Our precomputation and interpolation scheme, based on representing the reflected pressure with von-Mises-Fisher functions, is able to retain many directional and spectral features of the reflected pressure while keeping the computational and storage requirements low. We discuss our model and demonstrate applications of our precomputed functions in acoustic ray tracing and a novel interactive method suitable for applications such as architectural walk-throughs and video games.Eurographics Symposium on Parallel Graphics and Visualizatio
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