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15th International Conference on System Theory, Control and Computing, ICSTCC 2011

作者： Herghelegiu, Paul Manta, Vasile Gröpller, Eduard Faculty of Automatic Control and Computer Engineering Technical University Gheorghe Asachi Iasi Str. Prof. dr. doc. Dimitrie Mangeron 27 700050 Iasi Romania Vienna University of Technology Institute of Computer Graphics and Algorithms Favoritenstr. 9/5. Stock A-1040 Vienna Austria

ISBN: (纸本)9781457711732

Minimally invasive surgical procedures like biopsies require the insertion of a needle to reach a specific tissue from where samples are taken. This process is affected by a number of errors that can lead to a different needle pathway than originally planned. In the case of brain-tumor biopsies, these errors can be caused by the brain shifting when the skull is drilled, measurement errors due to the physical framework that supports the biopsy needle or some other human errors. To provide support for preoperative planning, we introduce the concept of a biopsy-needle stability-map. This map provides information on how stable a biopsy-needle pathway is. We also introduce an algorithm for finding the reachable points on the tumor border from one specific entry point. A technique for automatically selecting the needle pathway that offers the biggest minimal distance to any blood vessel is also presented. A 3D representation of the regions of interest (tumor, blood vessels) together with the needle pathway and the reachable points of the tumor has also been implemented. The resulting stability map visually represents, using color-coding, how close to any blood vessel the pathways surrounding the main one are. © 2011 Faculty of Auto Control.

关键词： Needles

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Christmas tree case study: computed tomography as a tool for mastering complex real world objects with applications in computer graphics 02

Christmas tree case study: computed tomography as a tool for...

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IEEE Conference on Visualization

作者： A. Kanitsar T. Theussl L. Mroz M. Sramek A.V. Bartroli B. Csebfalvi J. Hladuvka D. Fleischmann M. Knapp R. Wegenkittl P. Felkel S. Rottger S. Guthe W. Purgathofer M.E. Groller Institute of Computer Graphics and Algorithms Vienna University of Technology Austria Technische Universitat Wien Wien Wien AT Inst. of Comput. Graphics & Algorithms Vienna Univ. of Technol. Austria Tiani Medgraph Austria Austrian Academy of Sciences Vienna Austria Institute of Computer Graphics and Algorithms Vienna University of Technology Department of Radiology University of Technology Vienna Austria Department of Radiology University of Vienna Institute of Computer Graphics and Algorithms University of Technology Vienna Austria VRVis Research Center Vienna Austria VIS University of Stuttgart Germany WSI/GRIS University of Tübingen Germany

ISBN: (纸本)9780780374980

We report on using computed tomography (CT) as a model acquisition tool for complex objects in computer graphics. Unlike other modeling and scanning techniques the complexity of the object is irrelevant in CT, which naturally enables to model objects with, for example, concavities, holes, twists or fine surface details. Once the data is scanned, one can apply post-processing techniques for data enhancement, modification or presentation. For demonstration purposes we chose to scan a Christmas tree which exhibits high complexity which is difficult or even impossible to handle with other techniques. However, care has to be taken to achieve good scanning results with CT. Further, we illustrate post-processing by means of data segmentation and photorealistic as well as non-photorealistic surface and volume rendering techniques.

关键词： Tree graphs computer aided software engineering Computed tomography Application software computer graphics Rendering (computer graphics) Laser modes Radiology Image segmentation Chromium

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An Online Platform for Automatic Skull Defect Restoration and Cranial Implant Design

arXiv

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arXiv 2020年

作者： Li, Jianning Pepe, Antonio Gsaxner, Christina Egger, Jan Institute of Computer Graphics and Vision Graz University of Technology Computer Algorithms for Medicine Laboratory Graz Austria Department of Oral and Maxillofacial Surgery Medical University of Graz

We introduce a fully automatic system for cranial implant design, a common task in cranioplasty operations. The system is currently integrated in Studierfenster (http://***/), an online, cloud-based medical image processing platform for medical imaging applications. Enhanced by deep learning algorithms, the system automatically restores the missing part of a skull (i.e., skull shape completion) and generates the desired implant by subtracting the defective skull from the completed skull. The generated implant can be downloaded in the STereoLithography (.stl) format directly via the browser interface of the system. The implant model can then be sent to a 3D printer for in loco implant manufacturing. Furthermore, thanks to the standard format, the user can thereafter load the model into another application for post-processing whenever necessary. Such an automatic cranial implant design system can be integrated into the clinical practice to improve the current routine for surgeries related to skull defect repair (e.g., cranioplasty). Our system, although currently intended for educational and research use only, can be seen as an application of additive manufacturing for fast, patient-specific implant design. Copyright © 2020, The Authors. All rights reserved.

关键词： 3D printers

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Automated multi-contrast brain pathological area extraction from 2D MR images

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Journal of Applied Research and Technology 2015年第1期13卷 58-69页

作者： Dvořák, P. Bartušek, K. Kropatsch, W.G. Smékal, Z. Institute of Scientific Instruments of the ASCR V.v.i Academy if Sciences of the Czech Republic Brno Czech Republic Dept. of Telecommunications Faculty of Electrical Engineering and Communication Brno University of Technology Brno Czech Republic Pattern Recognition and Image Processing Group Institute of Computer Graphics and Algorithms Faculty of Informatics Vienna University of Technology Vienna Austria

The aim of this work is to propose the fully automated pathological area extraction from multi-parametric 2D MR images of brain. The proposed method is based on multi-resolution symmetry analysis and automatic thresholding. The proposed algorithm first detects the presence of pathology and then starts its extraction. T2 images are used for the presence detection and the multi-contrast MRI is used for the extraction, concretely T2 and FLAIR images. The extraction is based on thresholding, where Otsu's algorithm is used for the automatic determination of the threshold. Since the method is based on symmetry, it works for both axial and coronal planes. In both these planes of healthy brain, the approximate left-right symmetry exists and it is used as the prior knowledge for searching the approximate pathology location. It is assumed that this area is not located symmetrically in both hemispheres, which is met in most cases. The detection algorithm was tested on 203 T2-weighted images and reached the true positive rate of 87.52% and true negative rate of 93.14%. The extraction algorithm was tested on 357 axial and 443 coronal real images from publicly available BRATS databases containing 3D volumes brain tumor patients. The results were evaluated by Dice Coefficient (axial: 0.85 ± 0.11, coronal 0.82 ± 0.18) and by Accuracy (axial: 0.96 ± 0.05, coronal 0.94 ± 0.09). © 2015 Universidad Nacional Autónoma de México.

关键词： Brain Pathology Brain Tumor MRI Multi-contrast MRI Symmetry Analysis

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International Conference on Advances in Databases, Knowledge, and Data Applications, DBKDA

作者： Martin Suntinger Hannes Obweger Josef Schiefer Philip Limbeck Günther Raidl UC4 Senactive Software GmbH Vienna Austria Institute of Computer Graphics and Algorithms University of Technology Vienna Vienna Austria

ISBN: (纸本)9781424460816

In this paper, we present a novel approach towards time-series similarity search. Our technique relies on trends in a curve's movement over time. A trend is characterized by a series', values channeling in a certain direction (up, down, sideways) over a given time period before changing direction. We extract trend-turning points and utilize them for computing the similarity of two series based on the slopes between their turning points. For the turning point extraction, well-known techniques from financial market analysis are applied. The method supports queries of variable lengths and is resistant to different scaling of query and candidate sequence. It supports both subsequence searching and full sequence matching. One particular focus of this work is to enable simple modeling of query patterns as well as efficient similarity score updates in case of appending new data points.

关键词： Turning Electronic mail Pattern matching Databases Application software computer graphics Software algorithms Immune system Data analysis Time series analysis

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Seismic volume visualization for horizon extraction

Seismic volume visualization for horizon extraction

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Pacific (formerly Asia-Pacific APVIS) Visualization Symposium

作者： Daniel Patel Stefan Bruckner Ivan Viola Eduard M. Gröller Christian Michelsen Research Bergen Norway Institute of Computer Graphics and Algorithms University of Technology Vienna Austria Department of Informatics University of Bergen Norway

ISBN: (纸本)9781424466856

Seismic horizons indicate change in rock properties and are central in geoscience interpretation. Traditional interpretation systems involve time consuming and repetitive manual volumetric seeding for horizon growing. We present a novel system for rapidly interpreting and visualizing seismic volumetric data. First we extract horizon surface-parts by preprocessing the seismic data. Then during interaction the user can assemble in realtime the horizon parts into horizons. Traditional interpretation systems use gradient-based illumination models in the rendering of the seismic volume and polygon rendering of horizon surfaces. We employ realtime gradient-free forward-scattering in the rendering of seismic volumes yielding results similar to high-quality global illumination. We use an implicit surface representation of horizons allowing for a seamless integration of horizon rendering and volume rendering. We present a collection of novel techniques constituting an interpretation and visualization system highly tailored to seismic data interpretation.

关键词： Data visualization Lighting Fault diagnosis computer graphics Data mining Assembly Hydrocarbons Acoustic reflection Reservoirs Informatics

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Survey of the visual exploration and analysis of perfusion data

Survey of the visual exploration and analysis of perfusion d...

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作者： Preim, Bernhard Oeltze, Steffen Mlejnek, Matej Gröller, Eduard Hennemuth, Anja Behrens, Sarah Department of Simulation and Graphics Faculty of Computer Science University of Magdeburg Universitätsplatz 2 D-39106 Magdeburg Germany AGFA Healthcare Dietrichsteingasse 8/14 A-1090 Vienna Austria Institute of Computer Graphics and Algorithms Vienna University of Technology Favoritenstrasse 9-11/E186 A-1040 Vienna Austria MeVis Research Universitätsallee 29 D-28359 Bremen Germany MeVis Medical Solutions Universitätsallee 29 D-28359 Bremen Germany

Dynamic contrast-enhanced image data (perfusion data) are used to characterize regional tissue perfusion. Perfusion data consist of a sequence of images, acquired after a contrast agent bolus is applied. Perfusion data are used for diagnostic purposes in oncology, ischemic stroke assessment or myocardial ischemia. The diagnostic evaluation of perfusion data is challenging, since the data is complex and exhibits various artifacts, e.g., motion artifacts. We provide an overview on existing methods to analyze, and visualize CT and MR perfusion data. The integrated visualization of several 2D parameter maps, the 3D visualization of parameter volumes and exploration techniques are discussed. An essential aspect in the diagnosis of perfusion data is the correlation between perfusion data and derived time-intensity curves as well as with other image data, in particular with high resolution morphologic image data. We discuss visualization support with respect to the three major application areas: ischemic stroke diagnosis, breast tumor diagnosis and the diagnosis of coronary heart disease. © 2006 IEEE.

关键词： Volume rendering

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Computational Color Harmony based on Coloroid System

Computational Color Harmony based on Coloroid System

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1st Eurographics Workshop on Computational Aesthetics in graphics, Visualization, and Imaging, CAe 2005

作者： Neumann, László Nemcsics, Antal Neumann, Attila Grup de Gràfics de Girona Universitat de Girona Institució Catalana de Recerca i Estudis Avançats ICREA Barcelona Spain Budapest University of Technology and Economics Hungary Institute of Computer Graphics and Algorithms Vienna University of Technology Austria

ISBN: (纸本)3905673274

This paper presents experimentally based rules and methods for the creation of harmonic color sets. First, dichromatic rules are presented which concern the harmony relationships of two hues. For an arbitrarily given hue pair, we define the just harmonic saturation values, resulting in minimally harmonic color pairs. These values express the fuzzy border between harmony and disharmony regions using a single scalar. Second, the value of harmony is defined corresponding to the contrast of lightness, i.e. the difference of perceptual lightness values. Third, we formulate the harmony value of the saturation contrast, depending on hue and lightness. The results of these investigations form a basis for a unified, coherent dichromatic harmony formula as well as for analysis of polychromatic color harmony. Introduced color harmony rules are based on Coloroid, which is one of the 5 - 6 main color-order systems and furthermore it is an aesthetically uniform continuous color space. Coloroid has simple closed forward and backward transformation formulas with the color space of CIE XYZ. It relies on a huge number of observations and experiments, and it is a very suitable tool of color dynamics for describing aesthetical relationships. It has been used in numerous architectural projects. The experimental data that may be retrieved from them are only partly processed and published so far. Our article utilizes a’slice’ of this database, together with additional complementary observations. This paper is the first of a planned series of articles, dealing with rules and coherences of color harmony based on the Coloroid system. © The Eurographics Association 2005.

关键词： Color

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Variable Neighborhood Search for a Prize Collecting Capacity Constrained Connected Facility Location Problem

Variable Neighborhood Search for a Prize Collecting Capacity...

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Symposium on Applications and the Internet (SAINT)

作者： Markus Leitner Günther R. Raidl School of Telematics / Network Engineering Carinthia University of Applied Sciences Klagenfurt Austria Institute of Computer Graphics and Algorithms University of Technology Vienna Vienna Austria

We present a variable neighborhood search approach for a network design problem occurring in real world when the bandwidth of an existing network shall be enhanced. Using two different neighborhood structures we show that a carefully designed combination of a metaheuristic and an exact method based on integer linear programming is able to improve solution quality compared to using heuristic methods only.

关键词： Approximation methods Approximation algorithms Joining processes Fiber optics Optimization Force Algorithm design and analysis

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The Event Tunnel: Interactive Visualization of Complex Event Streams for Business Process Pattern Analysis

The Event Tunnel: Interactive Visualization of Complex Event...

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Pacific (formerly Asia-Pacific APVIS) Visualization Symposium

作者： Martin Suntinger Hannes Obweger Josef Schiefer M. Eduard Groller Senactive IT Dienstleistungs GmbH Austria Institute for Software Technology and Interactive Systems University of Technology Vienna Austria Institute of Computer Graphics and Algorithms University of Technology Vienna Austria

Event-based systems are gaining increasing popularity for building loosely coupled and distributed systems. Since business processes are becoming more interconnected and event-driven, event-based systems fit well for supporting and monitoring business processes. In this paper, we present an event-based business intelligence tool, the Event Tunnel framework. It provides an interactive visualization of event streams to support business analysts in exploring business incidents. The visualization is based on the metaphor of considering the event stream as a cylindrical tunnel, which is presented to the user from multiple perspectives. The information of single events laid out in the Event Tunnel is encoded in event glyphs that allow for a selective mapping of event attributes to colors, size and position. Different policies for the placement of the events in the tunnel as well as a clustering mechanism generate various views on historical event data. The Event Tunnel is able to display the relationships between events. This facilitates users to discover root causes and causal dependencies of event patterns. Our framework couples the event-tunnel visualization with query tools that allow users to search for relevant events within a data repository. Using query, filler and highlighting operations the analyst can navigate through the Event Tunnel until the required information or event patterns become visible. We demonstrate our approach with use cases from the fraud management and logistics domain.

关键词： Pattern analysis Data visualization Navigation Logistics Interactive systems computer graphics Software algorithms computerized monitoring Displays Information filtering

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