DevLan/vispubs huggingface dataset:
Interactive rendering of massive terrains on PC clusters
Authors: Valérie Gouranton, Souley Madougou, Emmanuel Melin, Cyril Nortet
Published at EuroVis, 2005

We 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.
Interactive Visualization for Neck-Dissection Planning
Authors: Arno Krüger, Christian Tietjen, Jana Hintze, Bernhard Preim, Ilka Hertel, Gero Strauß
Published at EuroVis, 2005

In 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.
Isosurface Extraction Using Fixed-Sized Buckets
Authors: Kenneth W. Waters, Christopher S. Co, Kenneth I. Joy
Published at EuroVis, 2005

We 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.
Localized Flow Analysis of 2D and 3D Vector Fields
Authors: Alexander Wiebel, Christoph Garth, Gerik Scheuermann
Published at EuroVis, 2005

In 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.
Mail Explorer - Spatial and Temporal Exploration of Electronic Mail
Authors: Daniel A. Keim, Florian Mansmann, Christian Panse, Jörn Schneidewind, Mike Sips
Published at EuroVis, 2005

In 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.
MoireTrees: Visualization and Interaction for Multi-Hierarchical Data
Authors: Mahnas Jean Mohammadi-Aragh, T. J. Jankun-Kelly
Published at EuroVis, 2005

Visualizing 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.
Non-manifold Mesh Extraction from Time-varying Segmented Volumes used for Modeling a Human Heart
Authors: Martin Bertram 0001, Gerd Reis, Rolf Hendrik van Lengen, Sascha Köhn, Hans Hagen
Published at EuroVis, 2005

We 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.
Pointillist and Glyph-based Visualization of Nanoparticles in Formation
Authors: P. Coleman Saunders, Victoria Interrante, Sean C. Garrick
Published at EuroVis, 2005

In 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.
Real-Time Advection and Volumetric Illumination for the Visualization of 3D Unsteady Flow
Authors: Daniel Weiskopf, Tobias Schafhitzel, Thomas Ertl
Published at EuroVis, 2005

This 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.
Scalable, Robust Visualization of Very Large Trees
Authors: Dale Beermann, Tamara Munzner, Greg Humphreys
Published at EuroVis, 2005

The 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.
Spatialized Transfer Functions
Authors: Stefan Röttger, Michael Bauer 0002, Marc Stamminger
Published at EuroVis, 2005

Multi-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.
Spline-Based Gradient Filters For High-Quality Refraction Computations in Discrete Datasets
Authors: Shengying Li, Klaus Mueller 0001
Published at EuroVis, 2005

Based 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.
The i-Disc - A Tool To Visualize and Explore Topic Maps
Authors: Tobias Hofmann, Hendrik Wendler, Bernd Froehlich 0001
Published at EuroVis, 2005

We 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.
Tiled Parallel Coordinates for the Visualization of Time-Varying Multichannel EEG Data
Authors: Michael ten Caat, Natasha M. Maurits, Jos B. T. M. Roerdink
Published at EuroVis, 2005

The 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.
Transfer Functions for Imaging Spectroscopy Data using Principal Component Analysis
Authors: Alexander Broersen, Robert van Liere
Published at EuroVis, 2005

In 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.
Vector Field Analysis and Visualization through Variational Clustering
Authors: Alexander McKenzie, Santiago V. Lombeyda, Mathieu Desbrun
Published at EuroVis, 2005

Scientific 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.
Version-Centric Visualization of Code Evolution
Authors: Lucian Voinea, Alexandru C. Telea, Michel R. V. Chaudron
Published at EuroVis, 2005

The 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.
VIS-a-VE: Visual Augmentation for Virtual Environments in Surgical Training
Authors: Adrian James Chung, Fani Deligianni, Pallav L. Shah, Athol Wells, Guang-Zhong Yang
Published at EuroVis, 2005

Photo-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.
VisBiz: A Business Process Visualization Case Study
Authors: Ming C. Hao, Daniel A. Keim, Umeshwar Dayal, Jörn Schneidewind
Published at EuroVis, 2005

Business 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.
Visualisation and Analysis of Large and Complex Scale-free Networks
Authors: Adel Ahmed, Tim Dwyer, Seok-Hee Hong 0001, Colin Murray, Le Song, Ying Xin Wu
Published at EuroVis, 2005

Scale-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.
Visualization for Validation and Improvement of Three-dimensional Segmentation Algorithms
Authors: Gunther H. Weber, Cris L. Luengo Hendriks, Soile V. E. Keränen, Scott E. Dillard, Derek Y. Ju, Damir Sudar, Bernd Hamann
Published at EuroVis, 2005

The Berkeley Drosophila Transcription 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 cellular 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 developing 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.