DevLan/vispubs huggingface dataset:
Boundary Switch Connectors for Topological Visualization of Complex 3D Vector Fields
Authors: Tino Weinkauf, Holger Theisel, Hans-Christian Hege, Hans-Peter Seidel
Published at EuroVis, 2004

One of the reasons that topological methods have a limited popularity for the visualization of complex 3D flow fields is the fact that their topological structures contain a number of separating stream surfaces. Since these stream surfaces tend to hide each other as well as other topological features, for complex 3D topologies the visualizations become cluttered and hardly interpretable. One solution of this problem is the recently introduced concept of saddle connectors which treats separation surfaces emanating from critical points. In this paper we extend this concept to separation surfaces starting from boundary switch curves. This way we obtain a number of particular stream lines called boundary switch connectors. They connect either two boundary switch curves or a boundary switch curve with a saddle. We discuss properties and computational issues of boundary switch connectors and apply them to topologically complex flow data.
Browsing and Visualizing Digital Bibliographic Data
Authors: Stefan Klink, Michael Ley, Emma Rabbidge, Patrick Reuther, Bernd Walter, Alexander Weber 0001
Published at EuroVis, 2004

Access to publications is provided by conventional libraries, digital libraries operated by learned societies or commercial publishers, and a huge number of web sites maintained by the scientists themselves or their institutions. But comprehensive meta-indices in combination with a helpful graphical user interface for this increasing number of information sources are missing for most areas of science.
 Our DBLP (Digital Bibliography & Library Project) Computer Science Bibliography is a major service used by thousands of computer scientists. It provides fundamental support for scientists searching for publications or other scientists in similar communities. For better assistance we developed a new browser prototype which has a user-friendly interface and plays a central role in the search and browsing of the data. The DBL-Browser provides smart search functions and several textual and graphical visualization models. This paper gives an overview of some important research issues within the field of bibliographical information retrieval and visualization. After introducing the whole framework, the DBL-Browser itself and various visualization models are described.
Case Study: Visual Analysis of Complex, Time-Dependent Simulation Results of a Diesel Exhaust System
Authors: Helmut Doleisch, Michael Mayer, Martin Gasser, Roland Wanker, Helwig Hauser
Published at EuroVis, 2004

In previous work we have presented visualization techniques that provide engineers with a high degree of interactivity and flexibility for analyzing large, time-dependent, and high-dimensional data sets resulting from CFD (computational fluid dynamics) simulations. In this case study we apply our techniques in the fields of the automotive engineering industry and demonstrate how users benefit from using them during their routine analysis, as well as for exploring new phenomena. For coping with some of the special requirements in this application, we adapted and extended parts of the system. A comparison of two related cases of a diesel exhaust system is presented, and some important questions about these cases are addressed.
Case Study: Visualization of annotated DNA sequences
Authors: Tim H. J. M. Peeters, Huub van de Wetering, Mark W. E. J. Fiers, Jarke J. van Wijk
Published at EuroVis, 2004

DNA sequences and their annotations form ever expanding data sets. Proper explorations of such data sets require new tools for visualization and analysis. In this case study, we have defined the requirements for a visualization tool for annotated DNA sequences. We have implemented these requirements in a new and flexible tool for browsing and comparing annotated DNA sequences interactively and in real-time. The use of standard information visualization techniques, such as linked windows, perspective walls, and smooth interaction, enables genome researchers to obtain better insight in large DNA data sets in an effective, efficient, and attractive way.
DTI Visualization with Streamsurfaces and Evenly-Spaced Volume Seeding
Authors: Anna Vilanova, G. Berenschot, Carola van Pul
Published at EuroVis, 2004

Experimental evidence has shown that water diffusion is anisotropic in organized tissues such as white matter or muscles. Diffusion Tensor Imaging is a non-invasive MR technique that measures water diffusion. DTI is used to visualize linear structures such as fibers. In this paper, we present a visualization tool for DTI data. A new algorithm to visualize linear structures in areas of crossing or converging fibers is presented. Usually the user defines an area from where the fibers are generated. In this way, the user can miss part of the information, if the area is not correctly defined. We present a method to visualize the structures in the whole volume with an evenly-spaced distance between them. Some results obtained by our partners using the DTI tool will be presented.
Efficient Display of Background Objects for Virtual Endoscopy using Flexible First-Hit Ray Casting
Authors: André Neubauer 0002, Marie-Thérèse Forster, Rainer Wegenkittl, Lukas Mroz, Katja Bühler
Published at EuroVis, 2004

Many applications of virtual endoscopy require the display of background objects behind the semi-transparent surface of the investigated organ. This paper deals with pre-processing and visualization of background objects for virtual endoscopy. A new first-hit ray casting technique for efficient perspective iso-surfacing of arbitrarily selected objects of interest is described: Visualization is performed without the use of dedicated hardware or data structures limiting flexibility (e.g., polygonal meshes or distance fields). The speedup is gained by exploiting inter-pixel coherency and by finding a near-optimal compromise between reduction of ray-tracking distances and limitation of the administrational cost associated with this reduction. The algorithm was developed by enhancing the previously published cell-based first-hit ray casting algorithm. This paper describes the original algorithm and explains the extensions needed to achieve interactive rendering of background objects.
Efficient Isosurface Tracking Using Precomputed Correspondence Table
Authors: Guangfeng Ji, Han-Wei Shen
Published at EuroVis, 2004

Feature tracking is a useful method for visualizing and analyzing time-varying scalar fields. It allows scientists to focus on regions of interest and track their evolution and interaction over time. To allow the user to freely explore the data set, features must be tracked in an efficient manner. In this paper, we present an efficient time-varying isosurface tracking algorithm. Unlike the previous algorithms which compute the corresponding isosurface components in the adjacent time steps by performing expensive computation at run time, our algorithm can rapidly identify corresponding isosurfaces by performing simple table lookup operations. This table, called the correspondence lookup table, can be computed at a preprocessing stage. The idea behind our approach is that the correspondence relationship can only change at critical isovalues in R3 or R4 and remains unchanged between adjacent pairs of critical isovalues. With our algorithm, isosurfaces can be tracked in an efficient manner with minimal overhead.
Generalized Distance Transforms and Skeletons in Graphics Hardware
Authors: Robert Strzodka, Alexandru C. Telea
Published at EuroVis, 2004

We present a framework for computing generalized distance transforms and skeletons of two-dimensional objects using graphics hardware. Our method is based on the concept of footprint splatting. Combining different splats produces weighted distance transforms for different metrics, as well as the corresponding skeletons and Voronoi diagrams. We present a hierarchical acceleration scheme and a subdivision scheme that allows visualizing the computed skeletons with subpixel accuracy in real time. Our splatting approach allows one to easily change all the metric parameters, treat any 2D boundaries, and easily produce both DTs and skeletons. We illustrate the method by several examples.
Graph Drawing by Subspace Optimization
Authors: Yehuda Koren
Published at EuroVis, 2004

We show a novel approach for accelerating the computation of graph drawing algorithms. The method is based on the notion that we can find a subspace with a relatively low dimensionality that captures the "nice" layouts of the graph. This way each axis of the drawing is a linear combination of a few basis vectors, instead of being an arbitrary vector in Rn (n is the number of nodes). We describe ways of constructing these basis vectors and also algorithms for optimizing the graph drawing in the resulting subspace.
High-Quality Lighting for Pre-Integrated Volume Rendering
Authors: Eric B. Lum, Brett Wilson, Kwan-Liu Ma
Published at EuroVis, 2004

Pre-integrated volume rendering is an effective technique for generating high-quality visualizations. The precomputed lookup tables used by this method are slow to compute and can not include truly pre-integrated lighting due to space constraints. The lighting for pre-integrated rendering is therefore subject to the same sampling artifacts as in standard volume rendering. We propose methods to speed up lookup table generation and minimize lighting artifacts. The incremental subrange integration method we describe allows interactive lookup table generation in O(n2) time without the need for approximation or hardware assistance. The interpolated preintegrated lighting algorithm eliminates discontinuities by linearly interpolating illumination along the view direction. Both methods are applicable to any pre-integrated rendering method, including cell projection, ray casting, and hardware-accelerated algorithms.
Illustrating Surfaces in Volume
Authors: Xiaoru Yuan, Baoquan Chen
Published at EuroVis, 2004

This paper presents a novel framework for illustrating surfaces in a volume. Surfaces are illustrated by drawing only feature lines, such as silhouettes, valleys, ridges, and surface hatching strokes, and are embedded in volume renderings. This framework promises effective illustration of both surfaces and volumes without occluding or cluttering each other. A two-step approach has been taken: the first step depicts surfaces; the second step performs volume rendering, at the same time embedding surfaces from the first step.
 We introduce Procedurally Perturbed Image Processing (PIP), a new method for enhancing both feature detection and depiction of surfaces. We also present implementation strategies, especially those leveraging modern graphics hardware, for delivering an interactive rendering system. Our implementation results have shown that this mixed form of rendering improves volume visualization and is efficient.
Interaction Spaces in Data and Information Visualization
Authors: Matthew O. Ward, Jing Yang 0001
Published at EuroVis, 2004

User interaction plays an integral part in the effective visualization of data and information. Typical interaction operations include navigation, selection, and distortion. A problem that can occur when these operations are speci£ed using direct manipulation is determining which object or space is the focus of the interaction. In some operations the user wants to indicate a region of an image, while in others the focus might be the data being projected or the surface upon which the projection is occurring. In this paper we attempt to identify a complete list of spaces within which interactive operations can occur in data and information visualization. These interaction spaces help disambiguate the focus of interactive operations, and their study can potentially reveal new and powerful methods for supporting the visual exploration process. We de£ne the distinctions between the spaces and provide examples of interactions within each space.
Interactive High Quality Trimmed NURBS Visualization Using Appearance Preserving Tessellation
Authors: Michael Guthe, Ákos Balázs, Reinhard Klein
Published at EuroVis, 2004

Trimmed NURBS models are the standard representation used in CAD/CAM systems and accurate visualization of large trimmed NURBS models at interactive frame rates is of great interest for industry. To visualize the quality of a surface several techniques like isophotes, reflection lines, etc. are used. Most existing approaches transform the NURBS surfaces into a fine polygonal representation and build static levels of detail from this representation. This polygonal approximation together with its normals are adjusted in a semi-automatic procedure to achieve the desired visual fidelity during visualization. Since this approach allows only for a fixed maximum accuracy and does not support deformable models, another more recent approach is to keep the NURBS representation and generate view-dependent LODs on the fly up to the currently required preciseness.
 However, so far this approach took only into account the geometric error of an approximation and thus neglected the various illumination artifacts introduced by the chosen (possibly view-dependent) triangulation. Although this problem can be solved by using normal maps, the resolution of the normal maps again limits the accuracy. Furthermore, the normal map generation requires a preprocessing step which prevents the support of deformable NURBS models. In this paper we present a novel automatic tessellation algorithm that considers the illumination artifacts and is well suited both for the generation of static and dynamic LOD schemes with guaranteed visual fidelity. Our new method is also capable of high quality visualization of further attributes like curvature, temperature, etc. on surfaces with little or no modification.
Interactive Treemaps With Detail on Demand to Support Information Search in Documents
Authors: Stefan Schlechtweg, Petra Schulze-Wollgast, Heidrun Schumann
Published at EuroVis, 2004

This paper addresses the issue of how information visualization techniques can be used to assist full-text search in electronic documents. Our approach supports multiple term queries with interactive treemaps. We use a treemap to visualize the basic structure of the document and exploit color coding to show the distribution of query terms on various levels of the hierarchy. Furthermore, we include filtering techniques to concentrate on those parts of the structure that actually contain the requested information, and, finally provide interactive tools to give access to detailed information whenever the user wishes.
Interactively Visualizing Procedurally Encoded Scalar Fields
Authors: Yun Jang, Manfred Weiler, Matthias Hopf, Jingshu Huang, David S. Ebert, Kelly P. Gaither, Thomas Ertl
Published at EuroVis, 2004

While interactive visualization of rectilinear gridded volume data sets can now be accomplished using texture mapping hardware on commodity PCs, interactive rendering and exploration of large scattered or unstructured data sets is still a challenging problem. We have developed a new approach that allows the interactive rendering and navigation of procedurally-encoded 3D scalar fields by reconstructing these fields on PC class graphics processing units. Since the radial basis functions (RBFs) we use for encoding can provide a compact representation of volumetric scalar fields, the large grid/mesh traditionally needed for rendering is no longer required and ceases to be a data transfer and computational bottleneck during rendering. Our new approach will interactively render RBF encoded data obtained from arbitrary volume data sets, including both structured volume models and unstructured scattered volume models. This procedural reconstruction of large data sets is flexible, extensible, and can take advantage of the Moore's Law cubed increase in performance of graphics hardware.
Isosurface Computation Made Simple
Authors: Valerio Pascucci
Published at EuroVis, 2004

This paper presents a simple approach for rendering isosurfaces of a scalar field. Using the vertex programming capability of commodity graphics cards, we transfer the cost of computing an isosurface from the Central Processing Unit (CPU), running the main application, to the Graphics Processing Unit (GPU), rendering the images. We consider a tetrahedral decomposition of the domain and draw one quadrangle (quad) primitive per tetrahedron. A vertex program transforms the quad into the piece of isosurface within the tetrahedron (see Figure 2). In this way, the main application is only devoted to streaming the vertices of the tetrahedra from main memory to the graphics card. For adaptively refined rectilinear grids, the optimization of this streaming process leads to the definition of a new 3D space-filling curve, which generalizes the 2D Sierpinski curve used for efficient rendering of triangulated terrains. We maintain the simplicity of the scheme when constructing view-dependent adaptive refinements of the domain mesh. In particular, we guarantee the absence of T-junctions by satisfying local bounds in our nested error basis. The expensive stage of fixing cracks in the mesh is completely avoided. We discuss practical tradeoffs in the distribution of the workload between the application and the graphics hardware. With current GPU's it is convenient to perform certain computations on the main CPU. Beyond the performance considerations that will change with the new generations of GPU's this approach has the major advantage of avoiding completely the storage in memory of the isosurface vertices and triangles.
Medical Applications of Multi-field Volume Rendering and VR Techniques
Authors: Joe Kniss, Jürgen P. Schulze, Uwe Wössner, Peter Winkler 0004, Ulrich Lang 0002, Charles D. Hansen
Published at EuroVis, 2004

This paper reports on a new approach for visualizing multi-field MRI or CT datasets in an immersive environment with medical applications. Multi-field datasets combine multiple scanning modalities into a single 3D, multivalued, dataset. In our approach, they are classified and rendered using real-time hardware accelerated volume rendering, and displayed in a hybrid work environment, consisting of a dual power wall and a desktop PC. For practical reasons in this environment, the design and use of the transfer functions is subdivided into two steps, classification and exploration. The classification step is done at the desktop, taking advantage of the 2D mouse as a high accuracy input device. The exploration process takes place on the powerwall. We present our new approach, describe the underlying implementation issues, report on our experiences with different immersive environments, and suggest ways it can be used for collaborative medical diagnosis and treatment planning.
Meshless Isosurface Generation from Multiblock Data
Authors: Christopher S. Co, Serban D. Porumbescu, Kenneth I. Joy
Published at EuroVis, 2004

We propose a meshless method for the extraction of high-quality continuous isosurfaces from volumetric data represented by multiple grids, also called "multiblock" data sets. Multiblock data sets are commonplace in computational mechanics applications. Relatively little research has been performed on contouring multiblock data sets, particularly when the grids overlap one another. Our algorithm proceeds in two steps. In the first step, we determine a continuous interpolant using a set of locally defined radial basis functions (RBFs) in conjunction with a partition of unity method to blend smoothly between these functions. In the second step, we extract isosurface geometry by sampling points on Marching Cubes triangles and projecting these point samples onto the isosurface defined by our interpolant. A surface splatting algorithm is employed for visualizing the resulting point set representing the isosurface. Because of our method's generality, it inherently solves the "crack problem" in isosurface generation. Results using a set of synthetic data sets and a discussion of practical considerations are presented. The importance of our method is that it can be applied to arbitrary grid data regardless of mesh layout or orientation.
Occlusion Culling for Sub-Surface Models in Geo-Scientific Applications
Authors: John Plate, Anselm Grundhöfer, Benjamin Schmidt, Bernd Fröhlich 0001
Published at EuroVis, 2004

Modern graphics cards support occlusion culling in hardware. We present a three pass algorithm, which makes efficient use of this feature. Our geo-scientific sub-surface data sets consist typically of a set of high resolution height fields, polygonal objects, and volume slices and lenses. For each height field, we compute a low and high resolution version in a pre-process and divide both into sets of corresponding tiles. For each tile and for the polygonal objects, the first rendering pass computes a z-buffer image using the low resolution tiles, the polygonal objects and the non-transparent volume objects. During the second pass, we render the same objects against the z-buffer of the first pass while submitting an occlusion query with each object. The third pass reads this occlusion information back from the graphics hardware and renders only those high resolution objects, for which the corresponding low resolution objects were not completely occluded. To avoid fill rate bottle necks, the first two passes may be rendered to a low resolution window. Our implementation shows frame rate improvements for all test cases while introducing only a small overhead and no or hardly noticeable errors. Our non-conservative approach does not require front to back sorting and it works for dynamic scenes.
Ray Casting Curved-Quadratic Elements
Authors: David F. Wiley, Henry R. Childs, Bernd Hamann, Kenneth I. Joy
Published at EuroVis, 2004

We present a method for ray casting curved-quadratic elements in 3D. The advantages of this approach is that a curved element can be directly visualized. Conventionally, higher-order elements are tessellated with several linear elements so that standard visualization techniques can be applied to the linear elements. Our method primarily focuses on how to find an approximation to the intersection between a ray and a curved-quadratic element. Once this approximation is found, conventional accumulation and color mapping techniques can be applied to the approximation to produce a volumetric visualization of the element. A cutting plane implementation is also shown that leverages the ray casting technique.
Shape-Embedded-Histograms for Visual Data Mining
Authors: Amihood Amir, Reuven Kashi, Daniel A. Keim, Nathan S. Netanyahu, Markus Wawryniuk
Published at EuroVis, 2004

Scatterplots are widely used in exploratory data analysis and class visualization. The advantages of scatterplots are that they are easy to understand and allow the user to draw conclusions about the attributes which span the projection screen. Unfortunately, scatterplots have the overplotting problem which is especially critical when high-dimensional data are mapped to low-dimensional visualizations. Overplotting makes it hard to detect the structure in the data, such as dependencies or areas of high density.
 In this paper we show that by extending the concept of Pixel Validity (1) the problem of overplotting or occlusion can be avoided and (2) the user has the possibility to see information about an additional third variable. In our extension of the Pixel Validity concept, we summarize the data which are projected onto a given region by generating a histogram over the required attribute. This is then embedded in the visualization by a pixel-based technique.