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Automatic tuning of liver tissue model using simulated annealing and genetic algorithm heuristic approaches

AIP Conference Proceedings 2014年第1期1605卷 313-318页

作者： Salina Sulaiman Abdullah Bade Rechard Lee Siti Hasnah Tanalol Real-Time Computer Graphics and Visualization (GRAVS) School of Science and Technology Universiti Malaysia Sabah 88400 Kota Kinabalu Sabah Malaysia

Mass Spring Model (MSM) is a highly efficient model in terms of calculations and easy implementation. Mass, spring stiffness coefficient and damping constant are three major components of MSM. This paper focuses on identifying the coefficients of spring stiffness and damping constant using automated tuning method by optimization in generating human liver model capable of responding quickly. To achieve the objective two heuristic approaches are used, namely Simulated Annealing (SA) and Genetic Algorithm (GA) on the human liver model data set. The properties of the mechanical heart, which are taken into consideration, are anisotropy and viscoelasticity. Optimization results from SA and GA are then implemented into the MSM to model two human hearts, each with its SA or GA construction parameters. These techniques are implemented while making FEM construction parameters as benchmark. Step size response of both models are obtained after MSMs were solved using Fourth Order Runge-Kutta (RK4) to compare the elasticity response of both models. Remodelled time using manual calculation methods was compared against heuristic optimization methods of SA and GA in showing that model with automatic construction is more realistic in terms of realtime interaction response time. Liver models generated using SA and GA optimization techniques are compared with liver model from manual calculation. It shows that the reconstruction time required for 1000 repetitions of SA and GA is faster than the manual method. Meanwhile comparison between construction time of SA and GA model indicates that model SA is faster than GA with varying rates of time 0.110635 seconds/1000 repetitions. Real-time interaction of mechanical properties is dependent on rate of time and speed of remodelling process. Thus, the SA and GA have proven to be suitable in enhancing realism of simulated real-time interaction in liver remodelling.

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User-guided Compressed Sensing for Magnetic Resonance Angiography

User-guided Compressed Sensing for Magnetic Resonance Angiog...

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Annual International Conference of the IEEE Engineering in Medicine and Biology Society

作者： Changgong Zhang Martijn van de Giessen Elmar Eisemann Anna Vilanova Section of Computer Graphics and Visualization Delft University of Technology Division of Image Processing Department of Radiology Leiden University Medical Center

ISBN: (纸本)9781424479276

Compressed sensing (CS) magnetic resonance imaging (MRI) enables the reconstruction of MRI images with fewer samples in k-space. One requirement is that the acquired image has a sparse representation in a known transform domain. MR angiograms are already sparse in the image domain. They can be further sparsified through finite-differences. Therefore, it is a natural application for CS-MRI. However, low-contrast vessels are likely to disappear at high under-sampling ratios, since the commonly used l_1 reconstruction tends to underestimate the magnitude of the transformed sparse coefficients. These vessels, however, are likely to be clinically important for medical diagnosis. To avoid the fading of low-contrast vessels, we propose a user-guided CS MRI that is able to mitigate the reduction of vessel contrast within a region of interest (ROI). Simulations show that these low-contrast vessels can be well maintained via our method which results in higher local quality compared to conventional CS.

关键词： Image reconstruction Magnetic resonance imaging Compressed sensing Minimization Angiography Transforms Fading

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Procedural shape modeling in digital humanities: Potentials and issues

Lecture Notes in Computer Science (including subseries Lectu...

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Lecture Notes in computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 2014年 8355卷 64-77页

作者： Havemann, Sven Wagener, Olaf Fellner, Dieter Institute of Computer Graphics and Knowledge Visualization Graz University of Technology Austria Fraunhofer IGD and TU Darmstadt Germany Institut fur Europaische Kunstgeschichte University of Heidelberg Germany

Procedural modeling is a technology that has great potential to make the abundant variety of shapes that have to be dealt with in Digital Humanities accessible and understandable. There is a gap, however, between technology on the one hand and the needs and requirements of the users in the Humanities community. In this paper we analyze the reasons for the limited uptake of procedural modeling and sketch possible ways to circumvent the problem. The key insight is that we have to find matching concepts in both fields, which are on the one hand grounded in the way shape is explained, e.g., in art history, but which can also be formalized to make them accessible to digital computers. © Springer-Verlag Berlin Heidelberg 2014.

关键词： Image reconstruction

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An Introduction to Verification of visualization Techniques

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2015年

作者： Tiago Etiene Robert M. Kirby Claudio T. Silva

ISBN: (数字)9781627058346

As we increase our reliance on computer-generated information, often using it as part of our decision-making process, we must devise tools to assess the correctness of that information. Consider, for example, software embedded on vehicles, used for simulating aircraft performance, or used in medical imaging. In those cases, software correctness is of paramount importance as there"s little room for error. Software verification is one of the tools available to attain such goals. Verification is a well known and widely studied subfield of computer science and computational science and the goal is to help us increase confidence in the software implementation by verifying that the software does what it is supposed to do. The goal of this book is to introduce the reader to software verification in the context of visualization. In the same way we became more dependent on commercial software, we have also increased our reliance on visualization software. The reason is simple: visualization is the lens through which users can understand complex data, and as such it must be verified. The explosion in our ability to amass data requires tools not only to store and analyze data, but also to visualize it. This book is comprised of six chapters. After an introduction to the goals of the book, we present a brief description of both worlds of visualization (Chapter 2) and verification (Chapter 3). We then proceed to illustrate the main steps of the verification pipeline for visualization algorithms. We focus on two classic volume visualization techniques, namely, Isosurface Extraction (Chapter 4) and Direct Volume Rendering (Chapter 5). We explain how to verify implementations of those techniques and report the latest results in the field of verification of visualization techniques. The last chapter concludes the book and highlights new research topics for the future.

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Riemann-finsler multi-valued geodesic tractography for HARDI 4th

Riemann-finsler multi-valued geodesic tractography for HARDI

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4th Meeting on visualization and Processing of Tensors and Higher Order Descriptors for Multi-Valued Data, 2011

作者： Sepasian, Neda Ten Thije Boonkkamp, Jan H. M. Florack, Luc M. J. Ter Haar Romeny, Bart M. Vilanova, Anna Department of Biomedical Engineering Mathematics and Computer Science Eindhoven University of Technology PO Box 513 Eindhoven5600 MB Netherlands Mathematics and Computer Science Eindhoven University of Technology PO Box 513 Eindhoven5600 MB Netherlands Department of Biomedical Engineering Eindhoven University of Technology PO Box 513 Eindhoven5600 MB Netherlands Faculty Electrical Engineering Mathematics and Computer Science Computer Graphics and Visualization Delft University of Technology Delft Netherlands

ISBN: (纸本)9783642543005

We introduce a geodesic based tractography method for High Angular Resolution Diffusion Imaging (HARDI). The concepts used are similar to the ones in geodesic based tractography for Diffusion Tensor Imaging (DTI). In DTI, the inverse of the second-order diffusion tensor is used to define the manifold where the geodesics are traced. HARDI models have been developed to resolve complex fiber populations within a voxel, and higher order tensors (HOT) are possible representations for HARDI data. In our framework, we apply Finsler geometry, which extends Riemannian geometry to a directionally dependent metric. A Finsler metric is defined in terms of HARDI higher order tensors. Furthermore, the Euler-Lagrange geodesic equations are derived based on the Finsler geometry. In contrast to other geodesic based tractography algorithms, the multi-valued numerical solution of the geodesic equations can be obtained. This gives the possibility to capture all geodesics arriving at a single voxel instead of only computing the shortest one. Results are analyzed to show the potential and characteristics of our algorithm. © Springer-Verlag Berlin Heidelberg 2014.

关键词： Diffusion tensor imaging

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Visualizing time-dependent key performance indicator in a graph-based analysis

Visualizing time-dependent key performance indicator in a gr...

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International Conference on Emerging Technologies and Factory Automation (ETFA)

作者： Stefan Hesse Marcel Spehr Stefan Gumhold Rainer Groh Research & Innovation SAP AG Germany TU Dresden Computer Graphics and Visualization (CGV) lab Dresden Germany Chair of Media Design TU Dresden Dresden Germany

The usage of visual analytics during the analysis of business warehouse calculated key performance indicators is one emerging challenge in modern business applications. On the one hand, a complex network of key performance indicators has to be supervised. On the other hand, within this network only few key performance indicators change obviously within a short period of time. The sole mapping of the complexity of a network of key performance indicators to a graph-based visualization only covers static information and neglects temporal dependencies. We present a new visualization approach for the enrichment of graph-based visualizations of key performance indicator networks by introducing a multi-encoded visualization of additional functional, contextual and temporal information. The should help the user to understand relationships between KPIs and alert him if something is going wrong.

关键词： visualization Correlation Data visualization Business Image color analysis Data warehouses Analytical models

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Designing procedurally generated levels

Designing procedurally generated levels

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9th AAAI Conference on Artificial Intelligence and Interactive Digital Entertainment, AIIDE 2013 Workshop

作者： Van Linden, Roland Der Lopes, Ricardo Bidarra, Rafael Computer Graphics and Visualization Group Delft University of Technology Netherlands

ISBN: (纸本)9781577356356

There is an increasing demand to improve the procedural generation of game levels. Our approach empowers game designers to author and control level generators, by expressing gameplay-related design constraints. Graph grammars, resulting from these designer-expressed constraints, can generate sequences of desired player actions as well as their associated target content. These action graphs are used to determine layouts and content for game levels. We showcase this approach with a case study on a dungeon crawler game. Results allow us to conclude that our control mechanisms are both expressive and powerful, effectively supporting designers to procedurally generate levels. Copyright © 2013, Association for the Advancement of Artificial Intelligence. All rights reserved.

关键词： Formal languages

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A generic method for classification of player behavior

A generic method for classification of player behavior

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9th AAAI Conference on Artificial Intelligence and Interactive Digital Entertainment, AIIDE 2013 Workshop

作者： Etheredge, Marlon Lopes, Ricardo Bidarra, Rafael Computer Graphics and Visualization Group Delft University of Technology Netherlands

ISBN: (纸本)9781577356356

Player classification allows for considerable improvements on both game analytics and game adaptivity. With this paper we aim at reversing the ad-hoc tendency in player classification methods, by proposing an approach to player classification that can be integrated across different games and genres and is particularly suited to be used by game designers. This paper describes our generic method of interaction-based player classification, which consists of three components: (i) intercepting player interactions, (ii) finding player types through fuzzy cluster analysis and (iii) classification using Hidden Markov Models (HMM). To showcase our method we developed Blindmaze, a simple web-based hidden maze game publicly available, featuring a bounded set of interactions. All data collected from a game is interaction-based, requiring minimal implementation effort from the game developers. It is concluded that our method makes player classification even more available by making it generic and reusable across different games. Copyright © 2013, Association for the Advancement of Artificial Intelligence. All rights reserved.

关键词： Cluster analysis

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Constructive Roof Geometry

Constructive Roof Geometry

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International Conference on Cyberworlds

作者： Johannes Edelsbrunner Ulrich Krispel Sven Havemann Alexei Sourin Dieter W. Fellner Institute for Computer Graphics and Knowledge Visualization (CGV) Graz University of Technology Graz Austria Fraunhofer Austria Research GmbH School of Computer Engineering Nanyang Technological University Singapore Graphisch-Interaktive System (GRIS) Darmstadt Germany Fraunhofer IGD TU Darmstadt Darmstadt Germany

While the growing demand for new building models contained in virtual worlds, games, and movies, makes the easy and fast creation of modifiable models more and more important, 3D modeling of buildings can be a tedious task due to their sometimes complex geometry. For historic buildings, especially the roofs can be challenging. We present a new method of combining simple building solids to form more complex buildings, and give an emphasis on the blending of roof faces. This can be integrated in common pipelines for procedural modeling of buildings and will bring more expressiveness than existing methods.

关键词： Buildings Solids Geometry Solid modeling Skeleton Three-dimensional displays Shape

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Progressive high-quality response surfaces for visually guided sensitivity analysis

Progressive high-quality response surfaces for visually guid...

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15th Eurographics Conference on visualization, EuroVis 2013

作者： Demir, I. Westermann, R. Computer Graphics and Visualization Group Technische Universität München Germany

In this paper we present a technique which allows us to perform high quality and progressive response surface prediction from multidimensional input samples in an efficient manner. We utilize kriging interpolation to estimate a response surface which minimizes the expectation value and variance of the prediction error. High computational efficiency is achieved by employing parallel matrix and vector operations on the GPU. Our approach differs from previous kriging approaches in that it uses a novel progressive updating scheme for new samples based on blockwise matrix inversion. In this way we can handle very large sample sets to which new samples are continually added. Furthermore, we can monitor the incremental evolution of the surface, providing a means to early terminate the computation when no significant changes have occurred. When the generation of input samples is fast enough, our technique enables steering this generation process interactively to find relevant dependency relations. © 2013 The Author(s).

关键词： Computational efficiency

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