EuroVis05: Joint Eurographics - IEEE VGTC Symposium on Visualization
Permanent URI for this collection
Real-Time Advection and Volumetric Illumination for the Visualization of 3D Unsteady Flow
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Weiskopf, Daniel
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Schafhitzel, Tobias
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Ertl, Thomas
Vector Field Analysis and Visualization through Variational Clustering
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McKenzie, Alexander
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Lombeyda, Santiago V.
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Desbrun, Mathieu
Dense Geometric Flow Visualization
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Park, Sung W.
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Budge, Brian
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Linsen, Lars
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Hamann, Bernd
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Joy, Kenneth I.
The i-Disc - A Tool To Visualize and Explore Topic Maps
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Hofmann, Tobias
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Wendler, Hendrik
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Froehlich, Bernd
Scalable, Robust Visualization of Very Large Trees
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Beermann, Dale
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Munzner, Tamara
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Humphreys, Greg
ArcTrees: Visualizing Relations in Hierarchical Data
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Neumann, Petra
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Schlechtweg, Dr. Stefan
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Carpendale, Sheelagh
Tiled Parallel Coordinates for the Visualization of Time-Varying Multichannel EEG Data
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Caat, Michael ten
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Maurits, N. M.
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Roerdink, J. B. T. M.
High-Quality Rendering of Compressed Volume Data Formats
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Fout, Nathaniel
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Akiba, Hiroshi
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Ma, Kwan-Liu
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Lefohn, Aaron E.
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Kniss, Joe
Illustrative Context-Preserving Volume Rendering
Bruckner, Stefan
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Grimm, Sören
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Kanitsar, Armin
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Gröller, M. Eduard
High-Quality Volume Rendering with Resampling in the Frequency Domain
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Artner, Martin
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Möller, Torsten
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Viola, Ivan
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Gröller, Meister E.
Visualization for Validation and Improvement of Three-dimensional Segmentation Algorithms
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Weber, Gunther H.
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Hendriks, Cris L. Luengo
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Keränen, Soile V. E.
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Dillard, Scott E.
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Ju, Derek Y.
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Sudar, Damir
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Hamann, Bernd
VIS-a-VE: Visual Augmentation for Virtual Environments in Surgical Training
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Chung, Adrian
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Deligianni, Fani
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Shah, Pallav
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Wells, Athol
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Yang, Guang-Zhong
Transfer Functions for Imaging Spectroscopy Data using Principal Component Analysis
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Broersen, Alexander
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Liere, Robert van
VisBiz: A Business Process Visualization Case Study
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Hao, Ming
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Keim, Daniel A.
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Dayal, Umeshwar
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Schneidewind, Joern
Interactive rendering of massive terrains on PC clusters
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Gouranton, V.
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Madougou, Souley
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Melin, Emmanuel
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Nortet, Cyril
Localized Flow Analysis of 2D and 3D Vector Fields
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Wiebel, Alexander
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Garth, Christoph
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Scheuermann, Gerik
A Simple and Novel Seed-Set Finding Approach for Iso-Surface Extraction
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Hung, Chiang-Han
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Yang, Chuan-kai
Analysis and Visualization of 3-C PIV Images from HART II using Image Processing Methods
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Ebling, Julia
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Scheuermann, Gerik
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Wall, Berend G. van der
Galilean Invariant Extraction and Iconic Representation of Vortex Core Lines
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Sahner, Jan
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Weinkauf, Tino
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Hege, Hans-Christian
Hardware-Accelerated Glyphs for Mono- and Dipoles in Molecular Dynamics Visualization
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Reina, Guido
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Ertl, Thomas
Pointillist and Glyph-based Visualization of Nanoparticles in Formation
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Saunders, P. Coleman
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Interrante, Victoria
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Garrick, Sean C.
GVis: A Scalable Visualization Framework for Genomic Data
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Hong, Jin
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Jeong, Dong Hyun
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Shaw, Chris D
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Ribarsky, William
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Borodovsky, Mark
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Song, Chang
Visualization of Computer-Modeled Forests for Forest Management
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Mohammadi-Aragh, Mahnas Jean
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Fujisaki, Ikuko
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Irby, Derek
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Evans, David
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Moorhead, Robert
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Roberts, Scott
Isosurface Extraction Using Fixed-Sized Buckets
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Waters, Kenneth W.
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Co, Christopher S.
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Joy, Kenneth I.
Non-manifold Mesh Extraction from Time-varying Segmented Volumes used for Modeling a Human Heart
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Bertram, Martin
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Reis, Gerd
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Lengen, Rolf H. van
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Köhn, Sascha
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Hagen, Hans
Version-Centric Visualization of Code Evolution
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Voinea, S. Lucian
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Telea, Alexandru
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Chaudron, Michel
Spline-Based Gradient Filters For High-Quality Refraction Computations in Discrete Datasets
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Li, Shengying
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Mueller, Klaus
Visualisation and Analysis of Large and Complex Scale-free Networks
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Ahmed, Adel
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Dywer, Tim
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Hong, Seok-Hee
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Murray, Colin
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Song, Le
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Wu, Ying Xin
MoireTrees: Visualization and Interaction for Multi-Hierarchical Data
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Mohammadi-Aragh, Mahnas Jean
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Jankun-Kelly, T. J.
Extending and Simplifying Transfer Function Design in Medical Volume Rendering Using Local Histograms
Lundström, Claes
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Ljung, Patric
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Ynnerman, Anders
Discovering High-level Parameters for Visualization Design
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Bhagavatula, Srinivas
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Rheingans, Penny
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Jardins, Marie des
Mail Explorer - Spatial and Temporal Exploration of Electronic Mail
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Keim, Daniel A.
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Mansmann, Florian
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Panse, Christian
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Schneidewind, Jörn
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Sips, Mike
Spatialized Transfer Functions
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Roettger, Stefan
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Bauer, Michael
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Stamminger, Marc
Interactive Methods for Exploring Particle Simulation Data
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Co, Christopher S.
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Friedman, Alex
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Grote, David P.
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Vay, Jean-Luc
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Bethel, E. Wes
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Joy, Kenneth I.
Interactive Visualization for Neck-Dissection Planning
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Krüger, Arno
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Tietjen, Christian
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Hintze, Jana
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Preim, Bernhard
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Hertel, Ilka
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Strauß, Gero
BioBrowser: A Framework for Fast Protein Visualization
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Halm, Andreas
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Offen, Lars
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Fellner, Dieter W.
Combining Silhouettes, Surface, and Volume Rendering for Surgery Education and Planning
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Tietjen, Christian
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Isenberg, Tobias
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Preim, Bernhard
Browse
Recent Submissions
Item Dynamically Modelling Interaction(The Eurographics Association, 2005) May, Jon; Ken Brodlie and David Duke and Ken JoyTechnological advances are increasing the use of dynamic or changing displays, in many forms of interface. The increasing amount of information held on the Internet and in private government and commercial databases also requires more innovative approaches to retrieval and browsing than existing text-based search engines can provide.Item Real-Time Advection and Volumetric Illumination for the Visualization of 3D Unsteady Flow(The Eurographics Association, 2005) Weiskopf, Daniel; Schafhitzel, Tobias; Ertl, Thomas; Ken Brodlie and David Duke and Ken JoyThis paper presents an interactive technique for the dense texture-based visualization of unsteady 3D flow, taking into account issues of computational efficiency and visual perception. High efficiency is achieved by a novel 3D GPU-based texture advection mechanism that implements logical 3D grid structures by physical memory in the form of 2D textures. This approach results in fast read and write access to physical memory, independent of GPU architecture. Slice-based direct volume rendering is used for the final display. A real-time computation of gradients is employed to achieve volume illumination. Perception-guided volume shading methods are included, such as halos, cool/warm shading, or color-based depth cueing. The problems of clutter and occlusion are addressed by supporting a volumetric importance function that enhances features of the flow and reduces visual complexity in less interesting regions.Item Vector Field Analysis and Visualization through Variational Clustering(The Eurographics Association, 2005) McKenzie, Alexander; Lombeyda, Santiago V.; Desbrun, Mathieu; Ken Brodlie and David Duke and Ken JoyScientific computing is an increasingly crucial component of research in various disciplines. Despite its potential, exploration of the results is an often laborious task, owing to excessively large and verbose datasets output by typical simulation runs. Several approaches have been proposed to analyze, classify, and simplify such data to facilitate an informative visualization and deeper understanding of the underlying system. However, traditional methods leave much room for improvement. In this article we investigate the visualization of large vector fields, departing from accustomed processing algorithms by casting vector field simplification as a variational partitioning problem. Adopting an iterative strategy, we introduce the notion of vector "proxies" to minimize the distortion error of our simplification by clustering the dataset into multiple best-fitting characteristic regions. This error driven approach can be performed with respect to various similarity metrics, offering a convenient set of tools to design clear and succinct representations of high dimensional datasets. We illustrate the bene fits of such tools through visualization experiments of three-dimensional vector fields.Item Dense Geometric Flow Visualization(The Eurographics Association, 2005) Park, Sung W.; Budge, Brian; Linsen, Lars; Hamann, Bernd; Joy, Kenneth I.; Ken Brodlie and David Duke and Ken JoyWe present a flow visualization technique based on rendering geometry in a dense, uniform distribution. Flow is integrated using particle advection. By adopting ideas from texture-based techniques and taking advantage of parallelism and programmability of contemporary graphics hardware, we generate streamlines and pathlines addressing both steady and unsteady flow. Pipelining is used to manage seeding, advection, and expiration of streamlines/ pathlines with constant lifetime. We achieve high numerical accuracy by enforcing short particle lifetimes and employing a fourth-order integration method. The occlusion problem inherent to dense volumetric representations is addressed by applying multi-dimensional transfer functions (MDTFs), restricting particle attenuation to regions of certain physical behavior, or features. Geometry is rendered in graphics hardware using techniques such as depth sorting, illumination, haloing, flow orientation, and depth-based color attenuation to enhance visual perception. We achieve dense geometric three-dimensional flow visualization with interactive frame rates.Item The i-Disc - A Tool To Visualize and Explore Topic Maps(The Eurographics Association, 2005) Hofmann, Tobias; Wendler, Hendrik; Froehlich, Bernd; Ken Brodlie and David Duke and Ken JoyWe present the i-Disc, a tool to interactively visualize and explore medium sized topic maps. Topic maps contain two basic structures: the topic hierarchy and the associations between topics. Our system presents the topic hierarchy in a radial planar layout by encoding different hierarchy levels as separate rings. Associations are displayed on demand as three-dimensional arcs across the topic landscape. By separating these two topic map structures into different spatial dimensions, we untangle the often complex topic map graph. A perspective rendering of our layout generates a natural focus and context display. Our elementary circular design allows quick perception of the overall topic map structure while interactive navigation and exploration provide access to details on demand. The tool is implemented as a client-server application and integrates seamlessly into existing web based environments.Item Scalable, Robust Visualization of Very Large Trees(The Eurographics Association, 2005) Beermann, Dale; Munzner, Tamara; Humphreys, Greg; Ken Brodlie and David Duke and Ken JoyThe TreeJuxtaposer system [MGT*03] allowed visual comparison of large trees with guaranteed visibility of landmarks and Focus+Context navigation. While that system allowed exploration and comparison of larger datasets than previous work, it was limited to a single tree of 775,000 nodes by a large memory footprint. In this paper, we describe the theoretical limitations to TreeJuxtaposer's architecture that severely restrict its scalability. We provide two scalable, robust solutions to these limitations: TJC and TJC-Q. TJC is a system that supports browsing trees up to 15 million nodes by exploiting leading-edge graphics hardware while TJC-Q allows browsing trees up to 5 million nodes on commodity platforms. Both of these systems use a fast new algorithm for drawing and culling and benefit from a complete redesign of all data structures for more efficient memory usage and reduced preprocessing time.Item ArcTrees: Visualizing Relations in Hierarchical Data(The Eurographics Association, 2005) Neumann, Petra; Schlechtweg, Dr. Stefan; Carpendale, Sheelagh; Ken Brodlie and David Duke and Ken JoyIn this paper we present, ARCTREES, a novel way of visualizing hierarchical and non-hierarchical relations within one interactive visualization. Such a visualization is challenging because it must display hierarchical information in a way that the user can keep his or her mental map of the data set and include relational information without causing misinterpretation. We propose a hierarchical view derived from traditional Treemaps and augment this view with an arc diagram to depict relations. In addition, we present interaction methods that allow the exploration of the data set using Focus+Context techniques for navigation. The development was motivated by a need for understanding relations in structured documents but it is also useful in many other application domains such as project management and calendars.Item Tiled Parallel Coordinates for the Visualization of Time-Varying Multichannel EEG Data(The Eurographics Association, 2005) Caat, Michael ten; Maurits, N. M.; Roerdink, J. B. T. M.; Ken Brodlie and David Duke and Ken JoyThe field of visualization assists data interpretation in many areas, but some types of data are not manageable by existing visualization techniques. This holds in particular for time-varying multichannel EEG data. No existing technique can simultaneously visualize information from all channels in use and all time steps. To address this problem, a new visualization technique is presented, based on the parallel coordinate method and making use of a tiled organization. This tiled organization employs a two-dimensional row-column representation, rather than a one-dimensional arrangement in columns as used for the classical parallel coordinates. The usefulness of the new method, referred to as tiled parallel coordinates, is demonstrated by one particular type of EEG data. It can be applied to an arbitrary number of time steps, for the maximum number of channels currently in use. The general setup of the method makes it widely applicable to other time-varying multivariate data types.Item High-Quality Rendering of Compressed Volume Data Formats(The Eurographics Association, 2005) Fout, Nathaniel; Akiba, Hiroshi; Ma, Kwan-Liu; Lefohn, Aaron E.; Kniss, Joe; Ken Brodlie and David Duke and Ken JoyRendering directly from packed or compressed volume data formats using graphics hardware has advantages in terms of memory consumption and bandwidth, but results in lower-quality images due to the prohibitive cost of performing interpolation and gradient-based shading on the reconstructed data. The problem with the existing method lies in its close coupling of decompression and interpolation. We demonstrate that deferred filtering overcomes this problem by using a two-pass decompression and rendering strategy. With this method interpolation and gradient calculations are very efficient, allowing high quality rendering directly from packed or compressed volume data. We evaluate the cost of creating interpolated, gradient-shaded renderings using traditional on-the-fly decompression and deferred filtering, and show that deferred filtering can provide up to twenty times speed-up for high quality rendering.Item Illustrative Context-Preserving Volume Rendering(The Eurographics Association, 2005) Bruckner, Stefan; Grimm, Sören; Kanitsar, Armin; Gröller, M. Eduard; Ken Brodlie and David Duke and Ken JoyIn volume rendering it is very difficult to simultaneously visualize interior and exterior structures while preserving clear shape cues. Very transparent transfer functions produce cluttered images with many overlapping structures, while clipping techniques completely remove possibly important context information. In this paper we present a new model for volume rendering, inspired by techniques from illustration that provides a means of interactively inspecting the interior of a volumetric data set in a feature-driven way which retains context information. The context-preserving volume rendering model uses a function of shading intensity, gradient magnitude, distance to the eye point, and previously accumulated opacity to selectively reduce the opacity in less important data regions. It is controlled by two user-specified parameters. This new method represents an alternative to conventional clipping techniques, shares their easy and intuitive user control, but does not suffer from the drawback of missing context information.Item High-Quality Volume Rendering with Resampling in the Frequency Domain(The Eurographics Association, 2005) Artner, Martin; Möller, Torsten; Viola, Ivan; Gröller, Meister E.; Ken Brodlie and David Duke and Ken JoyThis work introduces a volume rendering technique that is conceptually based on the shear-warp factorization. We propose to perform the shear transformation in the frequency domain. Unlike the standard shear-warp algorithm, we allow for arbitrary sampling distances along the viewing rays, independent from the view direction. The accurate scaling of the volume slices is achieved by using the zero padding interpolation property. Finally, a high quality gradient estimation scheme is presented which uses the derivative theorem of the Fourier transform. Experimental results show that the presented method outperforms established algorithms in the quality of the produced images. If the data is sampled above the Nyquist rate the presented method is capable of a perfect reconstruction of the original function.Item Visualization for Validation and Improvement of Three-dimensional Segmentation Algorithms(The Eurographics Association, 2005) Weber, Gunther H.; Hendriks, Cris L. Luengo; Keränen, Soile V. E.; Dillard, Scott E.; Ju, Derek Y.; Sudar, Damir; Hamann, Bernd; Ken Brodlie and David Duke and Ken JoyThe Berkeley DrosophilaTranscription Network Project (BDTNP) is developing a suite of methods that will allow a quantitative description and analysis of three dimensional (3D) gene expression patterns in an animal with cel- lular resolution. An important component of this approach are algorithms that segment 3D images of an organism into individual nuclei and cells and measure relative levels of gene expression. As part of the BDTNP, we are devel- oping tools for interactive visualization, control, and verification of these algorithms. Here we present a volume visualization prototype system that, combined with user interaction tools, supports validation and quantitative determination of the accuracy of nuclear segmentation. Visualizations of nuclei are combined with information obtained from a nuclear segmentation mask, supporting the comparison of raw data and its segmentation. It is possible to select individual nuclei interactively in a volume rendered image and identify incorrectly segmented objects. Integration with segmentation algorithms, implemented in MATLAB, makes it possible to modify a segmentation based on visual examination and obtain additional information about incorrectly segmented objects. This work has already led to significant improvements in segmentation accuracy and opens the way to enhanced analysis of images of complex animal morphologies.Item VIS-a-VE: Visual Augmentation for Virtual Environments in Surgical Training(The Eurographics Association, 2005) Chung, Adrian; Deligianni, Fani; Shah, Pallav; Wells, Athol; Yang, Guang-Zhong; Ken Brodlie and David Duke and Ken JoyPhoto-realistic rendering combined with vision techniques is an important trend in developing next generation surgical simulation devices. Training with simulator is generally low in cost and more efficient than traditional methods that involve supervised learning on actual patients. Incorporating genuine patient data in the simulation can significantly improve the efficacy of training and skills assessment. In this paper, a photo-realistic simulation architecture is described that utilises patient-specific models for training in minimally invasive surgery. The datasets are constructed by combining computer tomographic images with bronchoscopy video of the same patient so that the three dimensional structures and visual appearance are accurately matched. Using simulators enriched by a library of datasets with sufficient patient variability, trainees can experience a wide range of realistic scenarios, including rare pathologies, with correct visual information. In this paper, the matching of CT and video data is accomplished by using a newly developed 2D/3D registration method that exploits a shape from shading similarity measure. Additionally, a method has been devised to allow shading parameter estimation by modelling the bidirectional reflectance distribution function (BRDF) of the visible surfaces. The derived BRDF is then used to predict the expected shading intensity such that a texture map independent of lighting conditions can be extracted. Thus new views can be generated that were not captured in the original bronchoscopy video, thus allowing free navigation of the acquired 3D model with enhanced photo-realism.Item Transfer Functions for Imaging Spectroscopy Data using Principal Component Analysis(The Eurographics Association, 2005) Broersen, Alexander; Liere, Robert van; Ken Brodlie and David Duke and Ken JoyIn this paper we present a new application of the principal component analysis (PCA) to generate multidimensional transfer functions. These transfer functions are needed in the volumetric visualization of spectral data to isolate regions that contain interesting peak-shaped features. Both large and small peaks can be equally important and represent the presence of different chemical elements in a dataset. Principal component analysis separates these peaks in different uncorrelated components and can simultaneously identify spatial patterns. This approach is characterized by the direct linkage between the resulting spectral and spatial components. Our method enables us to create an opacity map from these components. One or more mappings can be selected to highlight features in three-dimensional volume visualization.Item VisBiz: A Business Process Visualization Case Study(The Eurographics Association, 2005) Hao, Ming; Keim, Daniel A.; Dayal, Umeshwar; Schneidewind, Joern; Ken Brodlie and David Duke and Ken JoyBusiness process management involves many parameters and relationships and is modeled as complex business process workflows. A common way to analyze the process data is by using flowcharts. Visual analysis of a largescale chart, however, is too complex. In this case study, we employ a novel visualization technique, called VisBiz. VisBiz reduces data complexity by automatically analyzing operational data and abstracting the most critical parameters that influence business process. The basic idea is to select the most relevant parameters and layout them on a triple-attributes circular graph based on their relationships and user domain knowledge. VizBiz transforms the attributes to nodes and the process flows to lines. VisBiz derives a new process flow matrix to link the process of multiple circular graphs as the analyst introduces more parameters for further analysis. The results of the real-world credit card fraud study show the significant advantages of this technique in finding fraud distribution patterns and root causes of frauds.Item Interactive rendering of massive terrains on PC clusters(The Eurographics Association, 2005) Gouranton, V.; Madougou, Souley; Melin, Emmanuel; Nortet, Cyril; Ken Brodlie and David Duke and Ken JoyWe describe a parallel framework for interactive smooth rendering of massive terrains. We define a parallelization scheme for level of detail algorithms in cluster-based environments. The scheme relies on modern PC clusters capabilities to address the scalability issue of level of detail algorithms. To achieve this, we propose an eficient tile-based data partitioning method that allows both reducing load imbalance and solving the well-known border problem. At runtime level of detail computations are performed in parallel on cluster nodes. A hierarchical view frustum culling combined to a compression mechanism harnessing the frame-to-frame coherence are used to drastically reduce the inter-tasks communication overhead. We take into account level of detail algorithms visual quality issue by providing geomorphing and texturing supports. We are able to interactively and smoothly render terrains composed of hundreds of millions to billions of polygons on a cluster of 8 PCs.Item Localized Flow Analysis of 2D and 3D Vector Fields(The Eurographics Association, 2005) Wiebel, Alexander; Garth, Christoph; Scheuermann, Gerik; Ken Brodlie and David Duke and Ken JoyIn this paper we present an approach to the analysis of the contribution of a small subregion in a dataset to the global flow. To this purpose, we subtract the potential flow that is induced by the boundary of the sub-domain from the original flow. Since the potential flow is free of both divergence and rotation, the localized flow field retains the original features. In contrast to similar approaches, by making explicit use of the boundary flow of the subregion, we manage to isolate the region-specific flow that contains exactly the local contribution of the considered subdomain to the global flow. In the remainder of the paper, we describe an implementation on unstructured grids in both two and three dimensions. We discuss the application of several widely used feature extraction methods on the localized flow, with an emphasis on topological schemes.Item A Simple and Novel Seed-Set Finding Approach for Iso-Surface Extraction(The Eurographics Association, 2005) Hung, Chiang-Han; Yang, Chuan-kai; Ken Brodlie and David Duke and Ken JoyIso-surface extraction is one of the most important approaches for volume rendering, and iso-contouring is one of the most effective methods for iso-surface extraction. Unlike most other methods having their search domain to be the whole dataset, iso-contouring does its search only on a relatively small subset of the original data-set. This subset, called a seed-set, has the property that every iso-surface must intersect with it, and it could be built at the preprocessing time. When an iso-value is given at the run time, iso-contouring algorithm starts from the intersected cells in the seed-set, and gradually propagates to form the whole iso-surface. As smaller seed-sets offer less cell searching time, most existing iso-contouring algorithms concentrates on how to identify an optimal seed-set. In this paper, we propose a new and linear-time approach for seed-set construction. This presented algorithm could reduce the size of the generated seed-sets by up to one or two orders of magnitude, compared with other previously proposed fast (linear time) algorithms.Item Analysis and Visualization of 3-C PIV Images from HART II using Image Processing Methods(The Eurographics Association, 2005) Ebling, Julia; Scheuermann, Gerik; Wall, Berend G. van der; Ken Brodlie and David Duke and Ken JoyIn this paper, three-component particle image velocimetry (3-C PIV) measurements within the wake of a helicopter rotor from the HART II test are analyzed. These PIV-images are quite a challenge as the noise due to the measurement method and the inherent turbulence of the flow can not be distinguished. Furthermore, features are often hidden by a mean flow, which is influenced by vortices and therefore not easy to determine. The authors present some image processing methods adapted to these vector fields for the computation of position, size, and direction of the vortices in this data. These methods are quite robust in terms of noise and independent of any mean flow and therefore appropriate for this analysis. The results of the analysis allow a more descriptive and intuitive visualization of the vortices.Item Galilean Invariant Extraction and Iconic Representation of Vortex Core Lines(The Eurographics Association, 2005) Sahner, Jan; Weinkauf, Tino; Hege, Hans-Christian; Ken Brodlie and David Duke and Ken JoyWhile vortex region quantities are Galilean invariant, most methods for extracting vortex cores depend on the frame of reference. We present an approach to extracting vortex core lines independently of the frame of reference by extracting ridge and valley lines of Galilean invariant vortex region quantities. We discuss a generalization of this concept leading to higher dimensional features. For the visualization of extracted line features we use an iconic representation indicating their scale and extent. We apply our approach to datasets from numerical simulations and experimental measurements.Item Hardware-Accelerated Glyphs for Mono- and Dipoles in Molecular Dynamics Visualization(The Eurographics Association, 2005) Reina, Guido; Ertl, Thomas; Ken Brodlie and David Duke and Ken JoyWe present a novel visualization method for mono- and dipolar molecular simulations from thermodynamics that takes advantage of modern graphics hardware to interactively render specifically tailored glyphs. Our approach allows domain experts to visualize the results of molecular dynamics simulations with a higher number of particles than before and furthermore offers much better visual quality. We achieve this by transferring only visualization parameters to the GPU and by generating implicit surfaces directly in the fragment program. As a result, we can render up to 500.000 glyphs with about 10 fps displaying all the simulation results as geometrical properties that resemble the classical abstract representation used in this research area. Thus we enable researchers to visually assess the results of simulations of greater scale than before. We believe that the proposed method can be generalized to create other kinds of parametrized surfaces directly on graphics hardware to overcome the bandwidth bottleneck that exists between CPU and GPU.Item Pointillist and Glyph-based Visualization of Nanoparticles in Formation(The Eurographics Association, 2005) Saunders, P. Coleman; Interrante, Victoria; Garrick, Sean C.; Ken Brodlie and David Duke and Ken JoyIn this paper we offer new, texture-based methods for the visualization of multivariate data. These methods aim to more effectively convey the results of calculations simulating the formation of nanoparticles in turbulent fl ows. In these simulations, an entire distribution of nanoparticles is computed at every point across a two-dimensional slice of the data space, for every time step. Previous visualization methods have relied on multiple separate images to convey summary statistics about the datasets, including mean diameter and standard deviation of particle sizes. We introduce new methods based on texture which aim to enable the integrated understanding of the entire distribution of values at each point across the domain in terms of both summary statistics at each point and particle counts for various sizes of particles. Pointillism is used to represent the data at each point across the data range as a high-resolution texture. Circular glyphs can also be used to form a more discrete, spot-based texture, in which different characteristics of the distribution are encoded in various features of the spots.Item GVis: A Scalable Visualization Framework for Genomic Data(The Eurographics Association, 2005) Hong, Jin; Jeong, Dong Hyun; Shaw, Chris D; Ribarsky, William; Borodovsky, Mark; Song, Chang; Ken Brodlie and David Duke and Ken JoyThis paper describes a framework we have developed for the visual analysis of large-scale phylogeny hierarchies populated with the genomic data of various organisms. This framework allows the user to quickly browse the phylogeny hierarchy of organisms from the highest level down to the level of an individual genome for the desired organism of interest. Based on this framework, the user can initiate gene-finding and gene-matching analyses and view the resulting annotated coding potential graphs in the same multi-scale visualization framework, permitting correlative analysis and further investigation. This paper introduces our framework and describes the data structures and algorithms that support it.Item Visualization of Computer-Modeled Forests for Forest Management(The Eurographics Association, 2005) Mohammadi-Aragh, Mahnas Jean; Fujisaki, Ikuko; Irby, Derek; Evans, David; Moorhead, Robert; Roberts, Scott; Ken Brodlie and David Duke and Ken JoyForest management is a costly and time-consuming activity. Remote sensing has the potential to improve the process by making it cheaper and more efficient, but only if appropriate characteristics can be determined from computer-models. This paper describes the implementation of a forest visualization system and a corresponding user study that tests the accuracy of parameter estimation and forest characterization. The study uses data obtained from field-surveys to generate a computer-modeled forest. Five different stands were tested. Based on the quantitative results obtained, generally, there is no statistically significant difference in parameter estimation when comparing field-recorded videos and computer-generated videos.Item Isosurface Extraction Using Fixed-Sized Buckets(The Eurographics Association, 2005) Waters, Kenneth W.; Co, Christopher S.; Joy, Kenneth I.; Ken Brodlie and David Duke and Ken JoyWe present a simple and output optimal algorithm for accelerated isosurface extraction from volumetric data sets. Output optimal extraction algorithms perform an amount of work dominated by the size of the (output) isosurface rather than the size of the (input) data set. While several optimal methods have been proposed to accelerate isosurface extraction, these algorithms are relatively complicated to implement or require quantized values as input. Our method is based on a straightforward array data structure that only requires an auxiliary sorting routine for construction. The method works equally well for floating point data as it does for quantized data sets. We demonstrate how the data structure can exploit coherence between isosurfaces by performing searches incrementally. We show results for real application data validating the method's optimality.Item Non-manifold Mesh Extraction from Time-varying Segmented Volumes used for Modeling a Human Heart(The Eurographics Association, 2005) Bertram, Martin; Reis, Gerd; Lengen, Rolf H. van; Köhn, Sascha; Hagen, Hans; Ken Brodlie and David Duke and Ken JoyWe present a new algorithm extracting and fairing surfaces from segmented volumes composed of multiple materials. In a first pass, the material boundaries in the volume are smoothed considering signed distance functions for the individual materials. Second, we apply a marching-cubes-like contouring method providing initial meshes defining material boundaries. Non-manifold features emerge along lines where more than two materials encounter. Finally, the mesh geometry is relaxed in a constrained fairing process. We use our algorithm to construct a heart model from segmented time-varying magnetic resonance images. Information concerning the heart ontology is used to merge certain structures to functional units.Item Version-Centric Visualization of Code Evolution(The Eurographics Association, 2005) Voinea, S. Lucian; Telea, Alexandru; Chaudron, Michel; Ken Brodlie and David Duke and Ken JoyThe source code of software systems changes many times during the system lifecycle. We study how developers can get insight in these changes in order to understand the project context and the product artifacts. For this we propose new techniques for code evolution representation and visualization interaction from a version-centric perspective. Central to our approach is a line-based display of the changing code, where each file version is shown as a column and the horizontal axis shows time. We propose a version centric layout of line representations and a constrained interaction scheme that makes it easy to navigate. Additionally, we describe a cushion based technique to enhance visualization with information about stable evolution areas. We demonstrate the usefulness of our approach on real- life data sets.Item Spline-Based Gradient Filters For High-Quality Refraction Computations in Discrete Datasets(The Eurographics Association, 2005) Li, Shengying; Mueller, Klaus; Ken Brodlie and David Duke and Ken JoyBased on the finding that refraction imposes significantly higher demands onto gradient filters than illumination and shading, we evaluate the family of spline filters as a good alternative to the cubic filters, which so far have served as the gold standard of efficient yet high-quality interpolation filters in present visualization applications. Using a regular background texture to visualize the refractive properties of the volumetric object, we also describe an efficient scheme to achieve the effects of supersampling without incurring any extra raycasting overhead. Our results indicate that splines can be superior to the Catmull-Rom filter, with potentially less computational overhead, also offering a convenient means to adjust the extent of lowpassing and smoothing.Item Visualisation and Analysis of Large and Complex Scale-free Networks(The Eurographics Association, 2005) Ahmed, Adel; Dywer, Tim; Hong, Seok-Hee; Murray, Colin; Song, Le; Wu, Ying Xin; Ken Brodlie and David Duke and Ken JoyScale-free networks appear in many application domains such as social and biological networks [BA99, BB03, BO04]. Roughly speaking, scale-free networks have power-law degree distribution, ultra-short average path length and high clustering coefficient [BA99, BB03, BO04]. This paper presents new methods for visualising scale-free networks in three dimensions. To make effective use of the third dimension and minimise occlusion, we produce graph visulaisations with nodes constrained to lie on parallel planes or on the surface of spheres. We implement the algorithms using a variation of a fast force-directed graph layout method [QE00]. Results with real world data sets such as IEEE InfoVis citation and collaboration networks and a protein-protein interaction network show that our method can be useful for visual analysis of large and complex scale-free networks. We also discuss the issue of visualisation of evolving networks and network integration.Item MoireTrees: Visualization and Interaction for Multi-Hierarchical Data(The Eurographics Association, 2005) Mohammadi-Aragh, Mahnas Jean; Jankun-Kelly, T. J.; Ken Brodlie and David Duke and Ken JoyVisualizing hierarchical data is one of the core areas of information visualization. Most of these techniques focus on single hierarchies hierarchies with a single root element and a single path to each element. In contrast, this work focuses on the browsing of multi-hierarchies hierarchies with multiple roots or multiple paths per element. A radial focus+context display algorithm and interaction methods are introduced to explore such multi-hierarchical data. A series of examples demonstrate the effectiveness of our new visualization. Keywords: information visualization, focus+context, radial layout, hierarchical visualizationItem Extending and Simplifying Transfer Function Design in Medical Volume Rendering Using Local Histograms(The Eurographics Association, 2005) Lundström, Claes; Ljung, Patric; Ynnerman, Anders; Ken Brodlie and David Duke and Ken JoyDirect Volume Rendering (DVR) is known to be of diagnostic value in the analysis of medical data sets. However, its deployment in everyday clinical use has so far been limited. Two major challenges are that the current methods for Transfer Function (TF) construction are too complex and that the tissue separation abilities of the TF need to be extended. In this paper we propose the use of histogram analysis in local neighborhoods to address both these conflicting problems. To reduce TF construction difficulty, we introduce Partial Range Histograms in an automatic tissue detection scheme, which in connection with Adaptive Trapezoids enable efficient TF design. To separate tissues with overlapping intensity ranges, we propose a fuzzy classification based on local histograms as a second TF dimension. This increases the power of the TF, while retaining intuitive presentation and interaction.Item Discovering High-level Parameters for Visualization Design(The Eurographics Association, 2005) Bhagavatula, Srinivas; Rheingans, Penny; Jardins, Marie des; Ken Brodlie and David Duke and Ken JoyIn most graphics and visualization applications, the effects of the mapping parameters on the output domain are multidimensional, non-linear and discontinuous. The complexity of such mapping often makes it difficult for a user to manually explore and manipulate the design parameter space to produce the desired output. Computer assistance is therefore useful in setting the mapping parameter values to generate desired outputs. Existing systems rely on exploring the entire input parameter space, which can be time and resource-intensive, particularly if the number of input parameters is large. We introduce a new approach to handling a large number of mapping parameters more efficiently. The basis for our approach is the identification of a small and effective set of highlevel parameters that can be associated directly with the characteristics of the outputs. Users will have a better understanding of this small set of high-level parameters and can easily modify their values interactively to produce the desired outputs. We demonstrate this technique in manipulating mapping parameters for a non-photorealistic volume rendering application.Item Mail Explorer - Spatial and Temporal Exploration of Electronic Mail(The Eurographics Association, 2005) Keim, Daniel A.; Mansmann, Florian; Panse, Christian; Schneidewind, Jörn; Sips, Mike; Ken Brodlie and David Duke and Ken JoyIn today s world, e-mail has become one of the most important means of communication in business and private lives due to its efficiency. However, the problems start as soon as mail volumes go beyond the scope of human information processing capabilities. Firstly, time does not allow for leaving certain messages unanswered for a long time, and in certain cases, for reading all messages. Secondly, the dilemma of electronic filters leaves a choice of too many junk mails getting through versus a risk of solicited mails being dumped. In this paper we present a new interactive visual data mining approach for analyzing individual e-mail communication. It combines classical visual analytics (help to identify pattern such as peaks and trends over time) with geo-spatial map distortions (help to understand the routes of e-mails). Experiments show that our visual e-mail explorer produces useful and interesting visualizations of large collections of e-mail and is practical for exploring temporal and geo-spatial patterns hidden in the e-mail data.Item Spatialized Transfer Functions(The Eurographics Association, 2005) Roettger, Stefan; Bauer, Michael; Stamminger, Marc; Ken Brodlie and David Duke and Ken JoyMulti-dimensional transfer functions are an efficient way to visualize features in scalar volume data produced by CT or MRI scanners. However, the optimal transfer function is difficult to find in general. We present an automatic yet powerful method for the automatic setup of multi-dimensional transfer functions by adding spatial information to the histogram of a volume. Using this information we can easily classify the histogram and derive a transfer function by assigning unique colors to each class of the histogram. Each feature can be selected interactively by pointing and clicking at the corresponding class in the transfer function. In order to render the classified volume with adequate quality we propose an extension of the wellknown pre-integration technique. Furthermore, we demonstrate the flexibility of our approach by giving examples for the imaging of segmented, diffusion-tensor and multi-modal data.Item Interactive Methods for Exploring Particle Simulation Data(The Eurographics Association, 2005) Co, Christopher S.; Friedman, Alex; Grote, David P.; Vay, Jean-Luc; Bethel, E. Wes; Joy, Kenneth I.; Ken Brodlie and David Duke and Ken JoyIn this work, we visualize high-dimensional particle simulation data using a suite of scatterplot-based visualizations coupled with interactive selection tools. We use traditional 2D and 3D projection scatterplots as well as a novel oriented-disk rendering style to convey various information about the data. Interactive selection tools allow physicists to manually classify "interesting" sets of particles that are highlighted across multiple, linked views of the data. The power of our application is the ability to correspond new visual representations of the simulation data with traditional, well understood visualizations. This approach supports the interactive exploration of the high-dimensional space while promoting discovery of new particle behavior.Item Interactive Visualization for Neck-Dissection Planning(The Eurographics Association, 2005) Krüger, Arno; Tietjen, Christian; Hintze, Jana; Preim, Bernhard; Hertel, Ilka; Strauß, Gero; Ken Brodlie and David Duke and Ken JoyIn this paper, we present visualization techniques for neck dissection planning. These interventions are carried out to remove lymph node metastasis in the neck region. 3d visualization is intended to explore and to quantify anatomic and pathologic structures and thus support decisions concerning the surgical strategy. For this purpose we developed and combined visualization and interaction techniques such as cutaway views, silhouettes and colorcoded distances. In addition, a standardized procedure for processing and visualization of the patient data is presented.Item BioBrowser: A Framework for Fast Protein Visualization(The Eurographics Association, 2005) Halm, Andreas; Offen, Lars; Fellner, Dieter W.; Ken Brodlie and David Duke and Ken JoyThis paper presents a protein visualization system called BioBrowser, which provides high quality images at interactive frame rates for molecules of extreme size and complexity. This is achieved by a shift in the tessellation approach: triangle meshes are not produced a priori on a 'just-in-case' basis. Instead, tessellation happens 'justin- time' given a certain camera position, image size and interaction demand. Thus, our approach is based on multiresolution meshes and on new extensions of graphics hardware. The paper shows how to reduce geometric data by using subdivision surfaces for ribbon structures and molecular surfaces and by using billboards instead of spheres consisting of triangles. It also shows how to use fragment shaders to create a three dimensional appearance and realistic sphere intersections. The combination of these approaches leads to an image quality not yet seen in interactive visualization environments for molecules of that size/complexity. All the above methods are combined to gain a high performance configurable visualization system on standard hardware.Item Combining Silhouettes, Surface, and Volume Rendering for Surgery Education and Planning(The Eurographics Association, 2005) Tietjen, Christian; Isenberg, Tobias; Preim, Bernhard; Ken Brodlie and David Duke and Ken JoyWe introduce a flexible combination of volume, surface, and line rendering.We employ object-based edge detection because this allows a flexible parametrization of the generated lines. Our techniques were developed mainly for medical applications using segmented patient-individual volume datasets. In addition, we present an evaluation of the generated visualizations with 8 medical professionals and 25 laypersons. Integration of lines in conventional rendering turned out to be appropriate.