Conference stringclasses 6 values | Year int64 1.99k 2.03k | Title stringlengths 8 187 | DOI stringlengths 16 32 | Abstract stringlengths 128 7.15k ⌀ | Accessible bool 2 classes | Early bool 2 classes | AuthorNames-Deduped listlengths 1 24 | Award listlengths 0 2 | Resources listlengths 0 5 | ResourceLinks listlengths 0 10 |
|---|---|---|---|---|---|---|---|---|---|---|
Vis | 2,002 | Case study: the "Office of Real Soon Now" for visualization | 10.1109/VISUAL.2002.1183830 | As part of a larger effort exploring alternative display systems, Lawrence Livermore National Laboratory has installed systems in two offices that extend and update the previously described "Office of Real Soon Now" project to improve the value for visualization tasks. These new systems use higher resolution projectors driven by workstations that run Unix-based applications via Linux and support hardware-accelerated 3D graphics, even across the boundary between displays. | false | false | [
"Samuel P. Uselton"
] | [] | [] | [] |
Vis | 2,002 | Case study: Visual debugging of finite element codes | 10.1109/VISUAL.2002.1183819 | We present an innovative application developed at Sandia National Laboratories for visual debugging of unstructured finite element physics codes. Our tool automatically locates anomalous regions, such as inverted elements or nodes whose variable values lie outside a prescribed range, then extracts mesh subsets around these features for detailed examination. The subsets are viewed using color coding of variable values superimposed on the mesh structure. This allows the values and their relative spatial locations within the mesh to be correlated at a glance. Both topological irregularities and hot spots within the data stand out visually, allowing the user to explore the exact numeric values of the grid at surrounding points over time. We demonstrate the utility of this approach by debugging a cell inversion in a simulation of an exploding wire. | false | false | [
"Patricia Crossno",
"David H. Rogers 0001",
"Christopher J. Garasi"
] | [] | [] | [] |
Vis | 2,002 | Case study: Visualization and analysis of high Rayleigh number - 3D convection in the Earth's mantle | 10.1109/VISUAL.2002.1183813 | Data sets from large-scale simulations (up to 501/sup 3/ grid points) of mantle convection are analyzed with volume rendering of the temperature field and a new critical point analysis of the velocity field. As the Rayleigh number Ra is increased the thermal field develops increasingly thin plume-like structures along which heat is convected. These eventually break down and become turbulent. Visualization methods are used to distinguish between various models of heat conductivity and to develop an intuitive understanding of the structure of the flow. | false | false | [
"Gordon Erlebacher",
"David A. Yuen",
"Fabien Dubuffet"
] | [] | [] | [] |
Vis | 2,002 | Case study: Visualizing ocean flow vertical motions using Lagrangian-Eulerian time surfaces | 10.1109/VISUAL.2002.1183822 | Ocean model simulations commonly assume the ocean is hydrostatic, resulting in near zero vertical motion. The vertical motion found is typically associated with the variations of the thermocline depth over time, which are mainly a result of the development and movement of ocean fronts, eddies, and internal waves. A new technique, extended from Lagrangian-Eulerian Advection, is presented to help understand the variation of vertical motion associated with the change in thermocline depth over time. A time surface is correctly deformed in a single direction according to the flow. The evolution of the time surface is computed via a mixture of Eulerian and Lagrangian techniques. The dominant horizontal motion is textured onto the surface using texture advection, while both the horizontal and vertical motions are used to displace the surface. The resulting surface is shaded for enhanced contrast. Timings indicate that the overhead over standard 2D texture advection is no more than 12%. | false | false | [
"Josh Grant",
"Gordon Erlebacher",
"James F. O'Brien"
] | [] | [] | [] |
Vis | 2,002 | Christmas tree case study: computed tomography as a tool for mastering complex real world objects with applications in computer graphics | 10.1109/VISUAL.2002.1183812 | We report on using computed tomography (CT) as a model acquisition tool for complex objects in computer graphics. Unlike other modeling and scanning techniques the complexity of the object is irrelevant in CT, which naturally enables to model objects with, for example, concavities, holes, twists or fine surface details. Once the data is scanned, one can apply post-processing techniques for data enhancement, modification or presentation. For demonstration purposes we chose to scan a Christmas tree which exhibits high complexity which is difficult or even impossible to handle with other techniques. However, care has to be taken to achieve good scanning results with CT. Further, we illustrate post-processing by means of data segmentation and photorealistic as well as non-photorealistic surface and volume rendering techniques. | false | false | [
"Armin Kanitsar",
"Thomas Theußl",
"Lukas Mroz",
"Milos Srámek",
"Anna Vilanova",
"Balázs Csébfalvi",
"Jirí Hladuvka",
"Dominik Fleischmann",
"Michael Knapp",
"Rainer Wegenkittl",
"Petr Felkel",
"Stefan Röttger",
"Stefan Guthe",
"Werner Purgathofer",
"M. Eduard Gröller"
] | [] | [] | [] |
Vis | 2,002 | Comparative evaluation of visualization and experimental results using image comparison metrics | 10.1109/VISUAL.2002.1183790 | Comparative evaluation of visualization and experimental results is a critical step in computational steering. In this paper, we present a study of image comparison metrics for quantifying the magnitude of difference between visualization of a computer simulation and a photographic image captured from an experiment. We examined eleven metrics, including three spatial domain, four spatial-frequency domain and four HVS (human-vision system) metrics. Among these metrics, a spatial-frequency domain metric called 2nd-order Fourier comparison was proposed specifically for this work. Our study consisted of two stages: base cases and field trials. The former is a general study on a controlled comparison space using purposely selected data, and the latter involves imagery results from computational fluid dynamics and a rheological experiment. This study has introduced a methodological framework for analyzing image-level methods used in comparative visualization. For the eleven metrics considered, it has offered a set of informative indicators as to the strengths and weaknesses of each metric. In particular, we have identified three image comparison metrics that are effective in separating "similar" and "different" image groups. Our 2nd-order Fourier comparison metric has compared favorably with others in two of the three tests, and has shown its potential to be used for steering computer simulation quantitatively. | false | false | [
"Hualin Zhou",
"Min Chen 0001",
"Michael F. Webster"
] | [] | [] | [] |
Vis | 2,002 | Compressing polygon mesh geometry with parallelogram prediction | 10.1109/VISUAL.2002.1183768 | We present a generalization of the geometry coder by Touma and Gotsman (1998) to polygon meshes. We let the polygon information dictate where to apply the parallelogram rule that they use to predict vertex positions. Since polygons tend to be fairly planar and fairly convex, it is beneficial to make predictions within a polygon rather than across polygons. This, for example, avoids poor predictions due to a crease angle between polygons. Up to 90 percent of the vertices can be predicted this way. Our strategy improves geometry compression by 10 to 40 percent depending on (a) how polygonal the mesh is and (b) on the quality (planarity/convexity) of the polygons. | false | false | [
"Martin Isenburg",
"Pierre Alliez"
] | [] | [] | [] |
Vis | 2,002 | Computing singularities of 3D vector fields with geometric algebra | 10.1109/VISUAL.2002.1183786 | Critical points of a vector field are key to their characterization. Their positions as well as their indexes are crucial for understanding vector fields. Considerable work exists in 2D, but less is available for 3D or higher dimensions. Geometric algebra is a derivative of Clifford algebra that not only enables a succinct definition of the index of a critical point in higher dimension; it also provides insight and computational pathways for calculating the index. We describe the problems in terms of geometric algebra and present an octree based solution using the algebra for finding critical points and their index in a 3D vector field. | false | false | [
"Stephen Mann",
"Alyn P. Rockwood"
] | [] | [] | [] |
Vis | 2,002 | CPR - curved planar reformation | 10.1109/VISUAL.2002.1183754 | Visualization of tubular structures such as blood vessels is an important topic in medical imaging. One way to display tubular structures for diagnostic purposes is to generate longitudinal cross-sections in order to show their lumen, wall, and surrounding tissue in a curved plane. This process is called curved planar reformation (CPR). We present three different methods to generate CPR images. A tube-phantom was scanned with computed tomography (CT) to illustrate the properties of the different CPR methods. Furthermore we introduce enhancements to these methods: thick-CPR, rotating-CPR and multi-path-CPR. | false | false | [
"Armin Kanitsar",
"Dominik Fleischmann",
"Rainer Wegenkittl",
"Petr Felkel",
"M. Eduard Gröller"
] | [] | [] | [] |
Vis | 2,002 | Direct surface extraction from 3D freehand ultrasound images | 10.1109/VISUAL.2002.1183755 | This paper presents a new technique for the extraction of surfaces from 3D ultrasound data. Surface extraction from ultrasound data is challenging for a number of reasons including noise and artifacts in the images and nonuniform data sampling. A method is proposed to fit an approximating radial basis function to the group of data samples. An explicit surface is then obtained by iso-surfacing the function. In most previous 3D ultrasound research, a pre-processing step is taken to interpolate the data into a regular voxel array and a corresponding loss of resolution. We are the first to represent the set of semi-structured ultrasound pixel data as a single function. From this we are able to extract surfaces without first reconstructing the irregularly spaced pixels into a regular 3D voxel array. | false | false | [
"Youwei Zhang",
"Robert Rohling",
"Dinesh K. Pai"
] | [] | [] | [] |
Vis | 2,002 | Efficient compression and rendering of multi-resolution meshes | 10.1109/VISUAL.2002.1183794 | We present a method to code the multiresolution structure of a 3D triangle mesh in a manner that allows progressive decoding and efficient rendering at a client machine. The code is based on a special ordering of the mesh vertices which has good locality and continuity properties, inducing a natural multiresolution structure. This ordering also incorporates information allowing efficient rendering of the mesh at all resolutions using the contemporary vertex buffer mechanism. The performance of our code is shown to be competitive with existing progressive mesh compression methods, while achieving superior rendering speed. | false | false | [
"Zachi Karni",
"Alexander Bogomjakov",
"Craig Gotsman"
] | [] | [] | [] |
Vis | 2,002 | Efficient computation of the topology of level sets | 10.1109/VISUAL.2002.1183774 | This paper introduces two efficient algorithms that compute the Contour Tree of a 3D scalar field /spl Fscr/ and its augmented version with the Betti numbers of each isosurface. The Contour Tree is a fundamental data structure in scientific visualization that is used to preprocess the domain mesh to allow optimal computation of isosurfaces with minimal overhead storage. The Contour Tree can also be used to build user interfaces reporting the complete topological characterization of a scalar field. The first part of the paper presents a new scheme that augments the Contour Tree with the Betti numbers of each isocontour in linear time. We show how to extend the scheme with the Betti number computation without increasing its complexity. Thus, we improve on the time complexity from our previous approach from O(m log m) to O(n log n+m), where m is the number of tetrahedra and n is the number of vertices in the domain of /spl Fscr/. The second part of the paper introduces a new divide-and-conquer algorithm that computes the Augmented Contour Tree with improved efficiency. The central part of the scheme computes the output Contour Tree by merging two intermediate Contour Trees and is independent of the interpolant. In this way we confine any knowledge regarding a specific interpolant to an oracle that computes the tree for a single cell. We have implemented this oracle for the trilinear interpolant and plan to replace it with higher order interpolants when needed. The complexity of the scheme is O(n+t log n), where t is the number of critical points of /spl Fscr/. For the first time we can compute the Contour Tree in linear time in many practical cases when t=O(n/sup 1-/spl epsi//). Lastly, we report the running times for a parallel implementation of our algorithm, showing good scalability with the number of processors. | false | false | [
"Valerio Pascucci",
"Kree Cole-McLaughlin"
] | [
"TT"
] | [] | [] |
Vis | 2,002 | Efficient simplification of point-sampled surfaces | 10.1109/VISUAL.2002.1183771 | We introduce, analyze and quantitatively compare a number of surface simplification methods for point-sampled geometry. We have implemented incremental and hierarchical clustering, iterative simplification, and particle simulation algorithms to create approximations of point-based models with lower sampling density. All these methods work directly on the point cloud, requiring no intermediate tesselation. We show how local variation estimation and quadric error metrics can be employed to diminish the approximation error and concentrate more samples in regions of high curvature. To compare the quality of the simplified surfaces, we have designed a new method for computing numerical and visual error estimates for point-sampled surfaces. Our algorithms are fast, easy to implement, and create high-quality surface approximations, clearly demonstrating the effectiveness of point-based surface simplification. | false | false | [
"Mark Pauly",
"Markus H. Gross",
"Leif Kobbelt"
] | [] | [] | [] |
Vis | 2,002 | Evaluation of a multimodal interface for 3D terrain visualization | 10.1109/VISUAL.2002.1183802 | Novel speech and/or gesture interfaces are candidates for use in future mobile or ubiquitous applications. This paper describes an evaluation of various interfaces for visual navigation of a whole Earth 3D terrain model. A mouse driven interface, a speech interface, a gesture interface, and a multimodal speech and gesture interface were used to navigate to targets placed at various points on the Earth. This study measured each participant's recall of target identity, order, and location as a measure of cognitive load. Timing information as well as a variety of subjective measures including discomfort and user preference were taken. While the familiar and mature mouse interface scored best by most measures, the speech interface also performed well. The gesture and multimodal interface suffered from weaknesses in the gesture modality. Weaknesses in the speech and multimodal modalities are identified and areas for improvement are discussed. | false | false | [
"David M. Krum",
"Olugbenga Omoteso",
"William Ribarsky",
"Thad Starner",
"Larry F. Hodges"
] | [] | [] | [] |
Vis | 2,002 | Exploring scalar fields using critical isovalues | 10.1109/VISUAL.2002.1183772 | Isosurfaces are commonly used to visualize scalar fields. Critical isovalues indicate isosurface topology changes: the creation of new surface components, merging of surface components or the formation of holes in a surface component. Therefore, they highlight interesting isosurface behavior and are helpful in exploration of large trivariate data sets. We present a method that detects critical isovalues in a scalar field defined by piecewise trilinear interpolation over a rectilinear grid and describe how to use them when examining volume data. We further review varieties of the marching cubes (MC) algorithm, with the intention of preserving topology of the trilinear interpolant when extracting an isosurface. We combine and extend two approaches in such a way that it is possible to extract meaningful isosurfaces even when a critical value is chosen as the isovalue. | false | false | [
"Gunther H. Weber",
"Gerik Scheuermann",
"Hans Hagen",
"Bernd Hamann"
] | [] | [] | [] |
Vis | 2,002 | Exploring surface characteristics with interactive Gaussian images (a case study) | 10.1109/VISUAL.2002.1183828 | The Gauss map projects surface normals to a unit sphere, providing a powerful visualization of the geometry of a graphical object. it can be used to predict visual events caused by changes in lighting, shading, and camera control. We present an interactive technique for portraying the Gauss map of polygonal models, mapping surface normals and the magnitudes of surface curvature using a spherical projection. Unlike other visualizations of surface curvature, we create our Gauss map directly from polygonal meshes without requiring any complex intermediate calculations of differential geometry. For anything other than simple shapes, surface information is densely mapped into the Gaussian normal image, inviting the use of visualization techniques to amplify and emphasize details hidden within the wealth of data. We present the use of interactive visualization tools such as brushing and linking to explore the surface properties of solid shapes. The Gauss map is shown to be simple to compute, easy to view dynamically, and effective at portraying important features of polygonal models. | false | false | [
"Bradley C. Lowekamp",
"Penny Rheingans",
"Terry S. Yoo"
] | [] | [] | [] |
Vis | 2,002 | Face-based luminance matching for perceptual colormap generation | 10.1109/VISUAL.2002.1183788 | Most systems used for creating and displaying colormap-based visualizations are not photometrically calibrated. That is, the relationship between RGB input levels and perceived luminance is usually not known, due to variations in the monitor, hardware configuration, and the viewing environment. However, the luminance component of perceptually based colormaps should be controlled, due to the central role that luminance plays in our visual processing. We address this problem with a simple and effective method for performing luminance matching on an uncalibrated monitor. The method is akin to the minimally distinct border technique (a previous method of luminance matching used for measuring luminous efficiency), but our method relies on the brain's highly developed ability to distinguish human faces. We present a user study showing that our method produces equivalent results to the minimally distinct border technique, but with significantly improved precision. We demonstrate how results from our luminance matching method can be directly applied to create new univariate colormaps. | false | false | [
"Gordon L. Kindlmann",
"Erik Reinhard",
"Sarah H. Creem-Regehr"
] | [] | [] | [] |
Vis | 2,002 | Fast and reliable space leaping for interactive volume rendering | 10.1109/VISUAL.2002.1183775 | We present a fast and reliable space-leaping scheme to accelerate ray casting during interactive navigation in a complex volumetric scene, where we combine innovative space-leaping techniques in a number of ways. First, we derive most of the pixel depths at the current frame by exploiting the temporal coherence during navigation, where we employ a novel fast cell-based reprojection scheme that is more reliable than the traditional intersection-point based reprojection. Next, we exploit the object space coherence to quickly detect the remaining pixel depths, by using a precomputed accurate distance field that stores the Euclidean distance from each empty (background) voxel toward its nearest object boundary. In addition, we propose an effective solution to the challenging new-incoming-objects problem during navigation. Our algorithm has been implemented on a 16-processor SGI Power Challenge and reached interactive rendering rates at more than 10 Hz during the navigation inside 512/sup 3/ volume data sets acquired from both a simulation phantom and actual patients. | false | false | [
"Ming Wan",
"Aamir Sadiq",
"Arie E. Kaufman"
] | [] | [] | [] |
Vis | 2,002 | Fast view-dependent level-of-detail rendering using cached geometry | 10.1109/VISUAL.2002.1183783 | Level-of-detail rendering is essential for rendering very large, detailed worlds in real-time. Unfortunately, level-of-detail computations can be expensive, creating a bottleneck at the CPU. This paper presents the CABTT algorithm, an extension to existing binary-triangle-tree-based level-of-detail algorithms. Instead of manipulating triangles, the CABTT algorithm instead operates on clusters of geometry called aggregate triangles. This reduces CPU overhead, eliminating a bottleneck common to level-of-detail algorithms. Since aggregate triangles stay fixed over several frames, they may be cached on the video card. This further reduces CPU load and fully utilizes the hardware accelerated rendering pipeline on modern video cards. These improvements result in a fourfold increase in frame rate over ROAM at high detail levels. Our implementation renders an approximation of an 8 million triangle height field at 42 frames per second with an maximum error of 1 pixel on consumer hardware. | false | false | [
"Joshua Levenberg"
] | [] | [] | [] |
Vis | 2,002 | Fast visualization of plane-like structures in voxel data | 10.1109/VISUAL.2002.1183753 | We present a robust, noise-resistant criterion characterizing plane-like skeletons in binary voxel objects. It is based on a distance map and the geodesic distance along the object's boundary. A parameter allows us to control the noise sensitivity. If needed, homotopy with the original object might be reconstructed in a second step, using an improved distance ordered thinning algorithm. The skeleton is analyzed to create a geometric representation for rendering. Plane-like parts are transformed into an triangulated surface not enclosing a volume by a suitable triangulation scheme. The resulting surfaces have lower triangle count than those created with standard methods and tend to maintain the original geometry, even after simplification with a high decimation rate. Our algorithm allows us to interactively render expressive images of complex 3D structures, emphasizing independently plane-like and rod-like structures. The methods are applied for visualization of the microstructure of bone biopsies. | false | false | [
"Steffen Prohaska",
"Hans-Christian Hege"
] | [] | [] | [] |
Vis | 2,002 | GeneVis: visualization tools for genetic regulatory network dynamics | 10.1109/VISUAL.2002.1183781 | GeneVis provides a visual environment for exploring the dynamics of genetic regulatory networks. At present time, genetic regulation is the focus of intensive research worldwide, and computational aids are being called for to help in the research of factors that are difficult to observe directly. GeneVis provides a particle-based simulation of genetic networks and visualizes the process of this simulation as it occurs. Two dynamic visualization techniques are provided, a visualization of the movement of the regulatory proteins and a visualization of the relative concentrations of these proteins. Several interactive tools relate the dynamic visualizations to the underlying genetic network structure. | false | false | [
"Charles A. H. Baker",
"Sheelagh Carpendale",
"Przemyslaw Prusinkiewicz",
"Michael G. Surette"
] | [] | [] | [] |
Vis | 2,002 | Geometric surface smoothing via anisotropic diffusion of normals | 10.1109/VISUAL.2002.1183766 | This paper introduces a method for smoothing complex, noisy surfaces, while preserving (and enhancing) sharp, geometric features. It has two main advantages over previous approaches to feature preserving surface smoothing. First is the use of level set surface models, which allows us to process very complex shapes of arbitrary and changing topology. This generality makes it well suited for processing surfaces that are derived directly from measured data. The second advantage is that the proposed method derives from a well-founded formulation, which is a natural generalization of anisotropic diffusion, as used in image processing. This formulation is based on the proposition that the generalization of image filtering entails filtering the normals of the surface, rather than processing the positions of points on a mesh. | false | false | [
"Tolga Tasdizen",
"Ross T. Whitaker",
"Paul Burchard",
"Stanley J. Osher"
] | [] | [] | [] |
Vis | 2,002 | Geometric verification of swirling features in flow fields | 10.1109/VISUAL.2002.1183789 | In this paper, we present a verification algorithm for swirling features in flow fields, based on the geometry of streamlines. The features of interest in this case are vortices. Without a formal definition, existing detection algorithms lack the ability to accurately identify these features, and the current method for verifying the accuracy of their results is by human visual inspection. Our verification algorithm addresses this issue by automating the visual inspection process. It is based on identifying the swirling streamlines that surround the candidate vortex cores. We apply our algorithm to both numerically simulated and procedurally generated datasets to illustrate the efficacy of our approach. | false | false | [
"Ming Jiang 0005",
"Raghu Machiraju",
"David S. Thompson"
] | [] | [] | [] |
Vis | 2,002 | Horizon occlusion culling for real-time rendering of hierarchical terrains | 10.1109/VISUAL.2002.1183801 | We present a technique to perform occlusion culling for hierarchical terrains at run-time. The algorithm is simple to implement and requires minimal pre-processing and additional storage, yet leads to 2-4 times improvement in framerate for views with high degrees of occlusion. Our method is based on the well-known occlusion horizon algorithm. We show how to adapt the algorithm for use with hierarchical terrains. The occlusion horizon is constructed as the terrain is traversed in an approximate front to back ordering. Regions of the terrain are compared to the horizon to determine when they are completely occluded from the viewpoint. Culling these regions leads to significant savings in rendering. | false | false | [
"Brandon Lloyd",
"Parris K. Egbert"
] | [] | [] | [] |
Vis | 2,002 | Immersive volume visualization of seismic simulations: A case study of techniques invented and lessons learned | 10.1109/VISUAL.2002.1183814 | This paper is a documentation of techniques invented, results obtained and lessons learned while creating visualization algorithms to render outputs of large-scale seismic simulations. The objective is the development of techniques for a collaborative simulation and visualization shared between structural engineers, seismologists, and computer scientists. The computer graphics research community has been witnessing a large number of exemplary publications addressing the challenges faced while trying to visualize both large-scale surface and volumetric datasets lately. From a visualization perspective, issues like data preprocessing (simplification, sampling, filtering, etc.); rendering algorithms (surface and volume), and interaction paradigms (large-scale, highly interactive, highly immersive, etc.) have been areas of study. In this light, we outline and describe the milestones achieved in a large-scale simulation and visualization project, which opened the scope for combining existing techniques with new methods, especially in those cases where no existing methods were suitable. We elucidate the data simplification and reorganization schemes that we used, and discuss the problems we encountered and the solutions we found. We describe both desktop (high-end local as well as remote) interfaces and immersive visualization systems that we developed to employ interactive surface and volume rendering algorithms. Finally, we describe the results obtained, challenges that still need to be addressed, and ongoing efforts to meet the challenges of large-scale visualization. | false | false | [
"Prashant Chopra",
"Jörg Meyer 0003",
"Antonio Fernandez"
] | [] | [] | [] |
Vis | 2,002 | Integration of measurement tools in medical 3d visualizations | 10.1109/VISUAL.2002.1183752 | We discuss 3d interaction techniques for the quantitative analysis of spatial relations in medical visualizations. We describe the design and implementation of measurement tools to measure distances, angles and volumes in 3d visualizations. The visualization of measurement tools as recognizable 3d objects and a 3d interaction, which is both intuitive and precise, determines the usability of such facilities. Measurements may be carried out in 2d visualizations of the original radiological data and in 3d visualizations. The result of a measurement carried out in one view is also displayed in the other view appropriately. We discuss the validation of the obtained measures. Finally, we describe how some important measurement tasks may be solved automatically. | false | false | [
"Bernhard Preim",
"Christian Tietjen",
"Wolf Spindler",
"Heinz-Otto Peitgen"
] | [] | [] | [] |
Vis | 2,002 | Interactive rendering of large volume data sets | 10.1109/VISUAL.2002.1183757 | We present a new algorithm for rendering very large volume data sets at interactive frame rates on standard PC hardware. The algorithm accepts scalar data sampled on a regular grid as input. The input data is converted into a compressed hierarchical wavelet representation in a preprocessing step. During rendering, the wavelet representation is decompressed on-the-fly and rendered using hardware texture mapping. The level of detail used for rendering is adapted to the local frequency spectrum of the data and its position relative to the viewer. Using a prototype implementation of the algorithm we were able to perform an interactive walkthrough of large data sets such as the visible human on a single off-the-shelf PC. | false | false | [
"Stefan Guthe",
"Michael Wand 0001",
"Julius Gonser",
"Wolfgang Straßer"
] | [] | [] | [] |
Vis | 2,002 | Interactive spectral volume rendering | 10.1109/VISUAL.2002.1183763 | We describe a method for volume rendering using a spectral representation of colour instead of the traditional RGB model. It is shown how to use this framework for a novel exploration of datasets through enhanced transfer function design. Furthermore, our framework is extended to allow real-time re-lighting of the scene created with any rendering method. The technique of post-illumination is introduced to generate new spectral images for arbitrary light colours in real-time. Also a tool is described to design a palette of lights and materials having certain properties such as selective metamerism or colour constancy. Applied to spectral transfer functions, different light colours can accentuate or hide specific qualities of the data. In connection with post-illumination this provides a new degree of freedom for guided exploration of volumetric data, which cannot be achieved using the RGB model. | false | false | [
"Steven Bergner",
"Torsten Möller",
"Mark S. Drew",
"Graham D. Finlayson"
] | [] | [] | [] |
Vis | 2,002 | Interactive translucent volume rendering and procedural modeling | 10.1109/VISUAL.2002.1183764 | Direct volume rendering is a commonly used technique in visualization applications. Many of these applications require sophisticated shading models to capture subtle lighting effects and characteristics of volumetric data and materials. Many common objects and natural phenomena exhibit visual quality that cannot be captured using simple lighting models or cannot be solved at interactive rates using more sophisticated methods. We present a simple yet effective interactive shading model which captures volumetric light attenuation effects to produce volumetric shadows and the subtle appearance of translucency. We also present a technique for volume displacement or perturbation that allows realistic interactive modeling of high frequency detail for real and synthetic volumetric data. | false | false | [
"Joe Michael Kniss",
"Simon Premoze",
"Charles D. Hansen",
"David S. Ebert"
] | [] | [] | [] |
Vis | 2,002 | Interactive view-dependent rendering of large isosurfaces | 10.1109/VISUAL.2002.1183810 | We present an algorithm for interactively extracting and rendering isosurfaces of large volume datasets in a view-dependent fashion. A recursive tetrahedral mesh refinement scheme, based on longest edge bisection, is used to hierarchically decompose the data into a multiresolution structure. This data structure allows fast extraction of arbitrary isosurfaces to within user specified view-dependent error bounds. A data layout scheme based on hierarchical space filling curves provides access to the data in a cache coherent manner that follows the data access pattern indicated by the mesh refinement. | false | false | [
"Benjamin F. Gregorski",
"Mark A. Duchaineau",
"Peter Lindstrom 0001",
"Valerio Pascucci",
"Kenneth I. Joy"
] | [] | [] | [] |
Vis | 2,002 | Interactive visualization of complex plant ecosystems | 10.1109/VISUAL.2002.1183778 | We present a method for interactive rendering of large outdoor scenes. Complex polygonal plant models and whole plant populations are represented by relatively small sets of point and line primitives. This enables us to show landscapes faithfully using only a limited percentage of primitives. In addition, a hierarchical data structure allows us to smoothly reduce the geometrical representation to any desired number of primitives. The scene is hierarchically divided into local portions of geometry to achieve large reduction factors for distant regions. Additionally, the data reduction is adapted to the visual importance of geometric objects. This allows us to maintain the visual fidelity of the representation while reducing most of the geometry drastically. With our system, we are able to interactively render very complex landscapes with good visual quality. | false | false | [
"Oliver Deussen",
"Carsten Colditz",
"Marc Stamminger",
"George Drettakis"
] | [] | [] | [] |
Vis | 2,002 | Isometric embedding by surface reconstruction from distances | 10.1109/VISUAL.2002.1183782 | To display the intuitive meaning of an abstract metric it is helpful to look on an embedded surface with the same inner geometry as the given metric. The resulting partial differential equations have no standard solution. Only for some special cases satisfactory methods are known. I present a new algorithmic approach which is not based on differential equations. In contrast to other methods this technique also works if the embedding exists only locally. The fundamental idea is to estimate Euclidean distances, from which the surface is built up. In this paper I focus on the reconstruction of a surface from these estimated distances. Particular the influence of a perturbation of the distances on the shape of the resulting surface is investigated. | false | false | [
"Ingrid Hotz"
] | [] | [] | [] |
Vis | 2,002 | Kinetic visualization: a technique for illustrating 3D shape and structure | 10.1109/VISUAL.2002.1183805 | Motion provides strong visual cues for the perception of shape and depth, as demonstrated by cognitive scientists and visual artists. This paper presents a novel visualization technique-kinetic visualization -that uses particle systems to add supplemental motion cues which can aid in the perception of shape and spatial relationships of static objects. Based on a set of rules following perceptual and physical principles, particles flowing over the surface of an object not only bring out, but also attract attention to, essential information on the shape of the object that might not be readily visible with conventional rendering that uses lighting and view changes. Replacing still images with animations in this fashion, we demonstrate with both surface and volumetric models in the accompanying videos that in many cases the resulting visualizations effectively enhance the perception of three-dimensional shape and structure. The results of a preliminary user study that we have conducted also show evidence that the supplemental motion cues help. | false | false | [
"Eric B. Lum",
"Aleksander Stompel",
"Kwan-Liu Ma"
] | [] | [] | [] |
Vis | 2,002 | Level set segmentation from multiple non-uniform volume datasets | 10.1109/VISUAL.2002.1183773 | Typically 3-D MR and CT scans have a relatively high resolution in the scanning X-Y plane, but much lower resolution in the axial Z direction. This non-uniform sampling of an object can miss small or thin structures. One way to address this problem is to scan the same object from multiple directions. In this paper we describe a method for deforming a level set model using velocity information derived from multiple volume datasets with non-uniform resolution in order to produce a single high-resolution 3D model. The method locally approximates the values of the multiple datasets by fitting a distance-weighted polynomial using moving least-squares. The proposed method has several advantageous properties: its computational cost is proportional to the object surface area, it is stable with respect to noise, imperfect registrations and abrupt changes in the data, it provides gain-correction, and it employs a distance-based weighting to ensures that the contributions from each scan are properly merged into the final result. We have demonstrated the effectiveness of our approach on four multi-scan datasets, a Griffin laser scan reconstruction, a CT scan of a teapot and MR scans of a mouse embryo and a zucchini. | false | false | [
"Ken Museth",
"David E. Breen",
"Leonid Zhukov",
"Ross T. Whitaker"
] | [] | [] | [] |
Vis | 2,002 | Maximum entropy light source placement | 10.1109/VISUAL.2002.1183785 | Finding the "best" viewing parameters for a scene is a difficult but very important problem. Fully automatic procedures seem to be impossible as the notion of "best" strongly depends on human judgment as well as on the application. In this paper a solution to the sub-problem of placing light sources for given camera parameters is proposed. A light position is defined to be optimal, when the resulting illumination reveals more about the scene than illuminations from all other light positions, i.e. the light position maximizes information that is added to the image through the illumination. With the help of an experiment with several subjects we could adapt the information measure to the actually perceived information content. We present fast global optimization procedures and solutions for two and more light sources. | false | false | [
"Stefan Gumhold"
] | [] | [] | [] |
Vis | 2,002 | NASA's great zooms: a case study | 10.1109/VISUAL.2002.1183825 | This paper examines a series of NASA outreach visualizations created using several layers of remote sensing satellite data ranging from 4-kilometers per pixel to I-meter per pixel. The viewer is taken on a seamless, cloud free journey from a global view of the Earth down to ground level where buildings, streets, and cars are visible. The visualizations were produced using a procedural shader that takes advantage of accurate georegistration and color matching between images. The shader accurately and efficiently maps the data sets to geometry allowing for animations with few perceptual transitions among data sets. We developed a pipeline to facilitate the production of over twenty zoom visualizations. Millions of people have seen these visualizations through national and international media coverage. | false | false | [
"Gregory W. Shirah",
"Horace Mitchell"
] | [] | [] | [] |
Vis | 2,002 | Non-photorealistic volume rendering using stippling techniques | 10.1109/VISUAL.2002.1183777 | Simulating hand-drawn illustration techniques can succinctly express information in a manner that is communicative and informative. We present a framework for an interactive direct volume illustration system that simulates traditional stipple drawing. By combining the principles of artistic and scientific illustration, we explore several feature enhancement techniques to create effective, interactive visualizations of scientific and medical datasets. We also introduce a rendering mechanism that generates appropriate point lists at all resolutions during an automatic preprocess, and modifies rendering styles through different combinations of these feature enhancements. The new system is an effective way to interactively preview large, complex volume datasets in a concise, meaningful, and illustrative manner. Volume stippling is effective for many applications and provides a quick and efficient method to investigate volume models. | false | false | [
"Aidong Lu",
"Christopher J. Morris 0001",
"David S. Ebert",
"Penny Rheingans",
"Charles D. Hansen"
] | [
"BP"
] | [] | [] |
Vis | 2,002 | Optimized view-dependent rendering for large polygonal datasets | 10.1109/VISUAL.2002.1183760 | In this paper we are presenting a novel approach for rendering large datasets in a view-dependent manner. In a typical view-dependent rendering framework, an appropriate level of detail is selected and sent to the graphics hardware for rendering at each frame. In our approach, we have successfully managed to speed up the selection of the level of detail as well as the rendering of the selected levels. We have accelerated the selection of the appropriate level of detail by not scanning active nodes that do not contribute to the incremental update of the selected level of detail. Our idea is based on imposing a spatial subdivision over the view-dependence trees data-structure, which allows spatial tree cells to refine and merge in real-time rendering to comply with the changes in the active nodes list. The rendering of the selected level of detail is accelerated by using vertex arrays. To overcome the dynamic changes in the selected levels of detail we use multiple small vertex arrays whose sizes depend on the memory on the graphics hardware. These multiple vertex arrays are attached to the active cells of the spatial tree and represent the active nodes of these cells. These vertex arrays, which are sent to the graphics hardware at each frame, merge and split with respect to the changes in the cells of the spatial tree. | false | false | [
"Jihad El-Sana",
"Eitan Bachmant"
] | [] | [] | [] |
Vis | 2,002 | Oriented tensor reconstruction: tracing neural pathways from diffusion tensor MRI | 10.1109/VISUAL.2002.1183799 | In this paper we develop a new technique for tracing anatomical fibers from 3D tensor fields. The technique extracts salient tensor features using a local regularization technique that allows the algorithm to cross noisy regions and bridge gaps in the data. We applied the method to human brain DT-MRI data and recovered identifiable anatomical structures that correspond to the white matter brain-fiber pathways. The images in this paper are derived from a dataset having 121/spl times/88/spl times/60 resolution. We were able to recover fibers with less than the voxel size resolution by applying the regularization technique, i.e., using a priori assumptions about fiber smoothness. The regularization procedure is done through a moving least squares filter directly incorporated in the tracing algorithm. | false | false | [
"Leonid Zhukov",
"Alan H. Barr"
] | [] | [] | [] |
Vis | 2,002 | Out-of-core rendering of massive geometric environments | 10.1109/VISUAL.2002.1183759 | We present an external memory algorithm for fast display of very large and complex geometric environments. We represent the model using a scene graph and employ different culling techniques for rendering acceleration. Our algorithm uses a parallel approach to render the scene as well as fetch objects from the disk in a synchronous manner. We present a novel prioritized prefetching technique that takes into account LOD-switching and visibility-based events between successive frames. We have applied our algorithm to large gigabyte-sized environments that are composed of thousands of objects and tens of millions of polygons. The memory overhead of our algorithm is output sensitive and is typically tens of megabytes. In practice, our approach scales with the model sizes, and its rendering performance is comparable to that of an in-core algorithm. | false | false | [
"Gokul Varadhan",
"Dinesh Manocha"
] | [] | [] | [] |
Vis | 2,002 | PMR: point to mesh rendering, a feature-based approach | 10.1109/VISUAL.2002.1183770 | Within the field of computer graphics and visualization, it is often necessary to visualize polygonal models with large number of polygons. Display quality is mandatory, but it is also desirable to have the ability to rapidly update the display in order to facilitate interactive use. Point based rendering methods have been shown effective for this task. Building on this paradigm we introduce the PMR system which uses a hierarchy both in points and triangles for rendering. This hierarchy is fundamentally different from the ones used in existing methods. It is based on the feature geometry in the object space rather than its projection in the screen space. This provides certain advantages over the existing methods. | false | false | [
"Tamal K. Dey",
"James Hudson"
] | [] | [] | [] |
Vis | 2,002 | PRIMA: A case study of using information visualization techniques for patient record analysis | 10.1109/VISUAL.2002.1183817 | We have created an application, called PRIMA (Patient Record intelligent Monitoring and Analysis), which can be used to visualize and understand patient record data. It was developed to better understand a large collection of patient records of bone marrow transplants at Hadassah Hospital in Jerusalem, Israel. It is based on an information visualization toolkit, Opal, which has been developed at the IBM T.J. Watson Research Center. Opal allows intelligent, interactive visualization of a wide variety of different types of data. The PRIMA application is generally applicable to a wide range of patient record data, as the underlying toolkit is flexible with regard to the form of the input data. This application is a good example of the usefulness of information visualization techniques in the bioinformatics domain, as these techniques have been developed specifically to deal with diverse sets of often unfamiliar data. We illustrate several unanticipated findings which resulted from the use of a flexible and interactive information visualization environment. | false | false | [
"Donna L. Gresh",
"David A. Rabenhorst",
"Amnon Shabo",
"Shimon Slavin"
] | [] | [] | [] |
Vis | 2,002 | Probabilistic surfaces: point based primitives to show surface uncertainty | 10.1109/VISUAL.2002.1183769 | Efficient and informative visualization of surfaces with uncertainties is an important topic with many applications in science and engineering. Examples include environmental pollution borderline identification, identification of the limits of an oil basin, or discrimination between contaminated and healthy tissue in medicine. This paper presents an approach for such visualization using points as display primitives. The approach is to render each polygon as a collection of points and to displace each point from the surface in the direction of the surface normal by an amount proportional to some random number multiplied by the uncertainty level at that point. This approach can be used in combination with other techniques such as pseudo-coloring and shading to give rise to efficient and revealing visualizations. The method is used to visualize real and simulated tumor formations with uncertainty of tumor boundaries. | false | false | [
"Gevorg Grigoryan",
"Penny Rheingans"
] | [] | [] | [] |
Vis | 2,002 | QuadTIN: quadtree based triangulated irregular networks | 10.1109/VISUAL.2002.1183800 | Interactive visualization of large digital elevation models is of continuing interest in scientific visualization, GIS, and virtual reality applications. Taking advantage of the regular structure of grid digital elevation models, efficient hierarchical multiresolution triangulation and adaptive level-of-detail (LOD) rendering algorithms have been developed for interactive terrain visualization. Despite the higher triangle count, these approaches generally outperform mesh simplification methods that produce irregular triangulated network (TIN) based LOD representations. In this project we combine the advantage of a TIN based mesh simplification preprocess with high-performance quadtree based LOD triangulation and rendering at run-time. This approach, called QuadTIN, generates an efficient quadtree triangulation hierarchy over any irregular point set that may originate from irregular terrain sampling or from reducing oversampling in high-resolution grid digital elevation models. | false | false | [
"Renato Pajarola",
"Marc Antonijuan",
"Roberto Lario"
] | [] | [] | [] |
Vis | 2,002 | Rendering the first star in the Universe - A case study | 10.1109/VISUAL.2002.1183824 | For quantitative examination of phenomena that simultaneously occur on very different spatial and temporal scales, adaptive hierarchical schemes are required. A special numerical multilevel technique, associated with a particular hierarchical data structure, is so-called adaptive mesh refinement (AMR). It allows one to bridge a wide range of spatial and temporal resolutions and therefore gains increasing popularity. We describe the interplay of several visualization and VR software packages for rendering time dependent AMR simulations of the evolution of the first star in the universe. The work was done in the framework of a television production for Discovery Channel television, "The Unfolding Universe.". Parts of the data were taken from one of the most complex AMR simulation ever carried out: It contained up to 27 levels of resolution, requiring modifications to the texture based AMR volume rendering algorithm that was used to depict the density distribution of the gaseous interstellar matter. A voice and gesture controlled CAVE application was utilized to define camera paths following the interesting features deep inside the computational domains. Background images created from cosmological computational data were combined with the final renderings. | false | false | [
"Ralf Kähler",
"Donna J. Cox",
"Robert Patterson",
"Stuart Levy",
"Hans-Christian Hege",
"Tom Abel"
] | [] | [] | [] |
Vis | 2,002 | Scalable alignment of large-format multi-projector displays using camera homography trees | 10.1109/VISUAL.2002.1183793 | This paper presents a vision-based geometric alignment system for aligning the projectors in an arbitrarily large display wall. Existing algorithms typically rely on a single camera view and degrade in accuracy as the display resolution exceeds the camera resolution by several orders of magnitude. Naive approaches to integrating multiple zoomed camera views fail since small errors in aligning adjacent views propagate quickly over the display surface to create glaring discontinuities. Our algorithm builds and refines a camera homography tree to automatically register any number of uncalibrated camera images; the resulting system is both faster and significantly more accurate than competing approaches, reliably achieving alignment errors of 0.55 pixels on a 24-projector display in under 9 minutes. Detailed experiments compare our system to two recent display wall alignment algorithms, both on our 18 Megapixel display wall and in simulation. These results indicate that our approach achieves sub-pixel accuracy even on displays with hundreds of projectors. | false | false | [
"Han Chen",
"Rahul Sukthankar",
"Grant Wallace",
"Kai Li 0001"
] | [] | [] | [] |
Vis | 2,002 | Sea of images | 10.1109/VISUAL.2002.1183792 | A long-standing research problem in computer graphics is to reproduce the visual experience of walking through a large photorealistic environment interactively. On one hand, traditional geometry-based rendering systems fall short of simulating the visual realism of a complex environment. On the other hand, image-based rendering systems have to date been unable to capture and store a sampled representation of a large environment with complex lighting and visibility effects. In this paper, we present a "sea of images," a practical approach to dense sampling, storage, and reconstruction of the plenoptic function in large, complex indoor environments. We use a motorized cart to capture omnidirectional images every few inches on a eye-height plane throughout an environment. The captured images are compressed and stored in a multiresolution hierarchy suitable for real-time prefetching during an interactive walkthrough. Later, novel images are reconstructed for a simulated observer by resampling nearby captured images. Our system acquires 15,254 images over 1,050 square feet at an average image spacing of 1.5 inches. The average capture and processing time is 7 hours. We demonstrate realistic walkthroughs of real-world environments reproducing specular reflections and occlusion effects while rendering 15-25 frames per second. | false | false | [
"Daniel G. Aliaga",
"Thomas A. Funkhouser",
"Dimah Yanovsky",
"Ingrid Carlbom"
] | [] | [] | [] |
Vis | 2,002 | Seamster: inconspicuous low-distortion texture seam layout | 10.1109/VISUAL.2002.1183787 | Surface texturing aids the visualization of polygonal meshes by providing additional surface orientation cues and feature annotations. Such texturing is usually implemented via texture mapping, which is easier and more effective when the distortion of the mapping from the surface to the texture map is kept small. We have previously shown that distortion occurs when areas of high surface curvature are flattened into the texture map. By cutting the surface in these areas one can reduce texture map distortion at the expense of additional seam artifacts. This paper describes a faster technique for guiding a texture map seam through high distortion regions, while restricting the seam to regions of low visibility. This results in distortion reducing seams that are less visually distracting and take less time to compute. We have also observed that visibility considerations improve the speed of a recent method that adds cuts to reduce a surface genus. | false | false | [
"Alla Sheffer",
"John C. Hart"
] | [] | [] | [] |
Vis | 2,002 | Semotus Visum: a flexible remote visualization framework | 10.1109/VISUAL.2002.1183758 | By offering more detail and precision, large data sets can provide greater insights to researchers than small data sets. However, these data sets require greater computing resources to view and manage. Remote visualization techniques allow the use of computers that cannot be operated locally. The Semotus Visum framework applies a high-performance client-server paradigm to the problem. The framework utilizes both client and server resources via multiple rendering methods. Experimental results show the framework delivers high frame rates and low latency across a wide range of data sets. | false | false | [
"Eric Luke",
"Charles D. Hansen"
] | [] | [] | [] |
Vis | 2,002 | Simulating fire with texture splats | 10.1109/VISUAL.2002.1183779 | We propose the use of textured splats as the basic display primitives for an open surface fire model. The high-detail textures help to achieve a smooth boundary of the fire and gain the small-scale turbulence appearance. We utilize the Lattice Boltzmann Model (LBM) to simulate physically-based equations describing the fire evolution and its interaction with the environment (e.g., obstacles, wind and temperature). The property of fuel and non-burning objects are defined on the lattice of the computation domain. A temperature field is also incorporated to model the generation of smoke from the fire due to incomplete combustion. The linear and local characteristics of the LBM enable us to accelerate the computation with graphics hardware to reach real-time simulation speed, while the texture splat primitives enable interactive rendering frame rates. | false | false | [
"Xiaoming Wei",
"Wei Li 0004",
"Klaus Mueller 0001",
"Arie E. Kaufman"
] | [] | [] | [] |
Vis | 2,002 | Tensor field visualisation using adaptive filtering of noise fields combined with glyph rendering | 10.1109/VISUAL.2002.1183797 | While many methods exist for visualising scalar and vector data, visualisation of tensor data is still troublesome. We present a method for visualising second order tensors in three dimensions using a hybrid between direct volume rendering and glyph rendering. An overview scalar field is created by using three-dimensional adaptive filtering of a scalar field containing noise. The filtering process is controlled by the tensor field to be visualised, creating patterns that characterise the tensor field. By combining direct volume rendering of the scalar field with standard glyph rendering methods for detailed tensor visualisation, a hybrid solution is created. A combined volume and glyph renderer was implemented and tested with both synthetic tensors and strain-rate tensors from the human heart muscle, calculated from phase contrast magnetic resonance image data. A comprehensible result could be obtained, giving both an overview of the tensor field as well as detailed information on individual tensors. | false | false | [
"Andreas Sigfridsson",
"Tino Ebbers",
"Einar Heiberg",
"Lars Wigström"
] | [] | [] | [] |
Vis | 2,002 | TetFusion: an algorithm for rapid tetrahedral mesh simplification | 10.1109/VISUAL.2002.1183767 | This paper introduces an algorithm for rapid progressive simplification of tetrahedral meshes: TetFusion. We describe how a simple geometry decimation operation steers a rapid and controlled progressive simplification of tetrahedral meshes, while also taking care of complex mesh-inconsistency problems. The algorithm features a high decimation ratio per step, and inherently discourages any cases of self-intersection of boundary, element-boundary intersection at concave boundary-regions, and negative volume tetrahedra (flipping). We achieved rigorous reduction ratios of up to 98% for meshes consisting of 827,904 elements in less than 2 minutes, progressing through a series of level-of-details (LoDs) of the mesh in a controlled manner. We describe how the approach supports a balanced re-distribution of space between tetrahedral elements, and explain some useful control parameters that make it faster and more intuitive than 'edge collapse'-based decimation methods for volumetric meshes. Finally, we discuss how this approach can be employed for rapid LoD prototyping of large time-varying datasets as an aid to interactive visualization. | false | false | [
"Prashant Chopra",
"Jörg Meyer 0003"
] | [] | [] | [] |
Vis | 2,002 | Visibility-guided simplification | 10.1109/VISUAL.2002.1183784 | For some graphics applications, object interiors and hard-to-see regions contribute little to the final images and need not be processed. In this paper, we define a view-independent visibility measure on mesh surfaces based on the visibility function between the surfaces and a surrounding sphere of cameras. We demonstrate the usefulness of this measure with a visibility-guided simplification algorithm. Mesh simplification reduces the polygon counts of 3D models and speeds up the rendering process. Many mesh simplification algorithms are based on sequences of edge collapses that minimize geometric and attribute errors. By combining the surface visibility measure with a geometric error measure, we obtain simplified models with improvement proportional to the number of low visibility regions in the original models. | false | false | [
"Eugene Zhang",
"Greg Turk"
] | [] | [] | [] |
Vis | 2,002 | Visualizing dynamic molecular conformations | 10.1109/VISUAL.2002.1183780 | The bioactivity of a molecule strongly depends on its metastable conformational shapes and the transitions between these. Therefore, conformation analysis and visualization is a basic prerequisite for the understanding of biochemical processes. We present techniques for visual analysis of metastable molecular conformations. Core of these are flexibly applicable methods for alignment of molecular geometries, as well as methods for depicting shape and 'fuzziness' of metastable conformations. All analysis tools are provided in an integrated working environment. The described techniques are demonstrated with pharmaceutically active biomolecules. | false | false | [
"Johannes Schmidt-Ehrenberg",
"Daniel Baum",
"Hans-Christian Hege"
] | [] | [] | [] |
Vis | 2,002 | Volume clipping via per-fragment operations in texture-based volume visualization | 10.1109/VISUAL.2002.1183762 | We propose new clipping methods that are capable of using complex geometries for volume clipping. The clipping tests exploit per-fragment operations on the graphics hardware to achieve high frame rates. In combination with texture-based volume rendering, these techniques enable the user to interactively select and explore regions of the data set. We present depth-based clipping techniques that analyze the depth structure of the boundary representation of the clip geometry to decide which parts of the volume have to be clipped. In another approach, a voxelized clip object is used to identify the clipped regions. | false | false | [
"Daniel Weiskopf",
"Klaus Engel",
"Thomas Ertl"
] | [] | [] | [] |
Vis | 2,002 | Volume deformation for tensor visualization | 10.1109/VISUAL.2002.1183798 | Visualizing second-order 3D tensor fields continue to be a challenging task. Although there are several algorithms that have been presented, no single algorithm by itself is sufficient for the analysis because of the complex nature of tensor fields. In this paper, we present two new methods, based on volume deformation, to show the effects of the tensor field upon its underlying media. We focus on providing a continuous representation of the nature of the tensor fields. Each of these visualization algorithms is good at displaying some particular properties of the tensor field. | false | false | [
"Xiaoqiang Zheng",
"Alex T. Pang"
] | [] | [] | [] |
Vis | 2,002 | Volume warping for adaptive isosurface extraction | 10.1109/VISUAL.2002.1183809 | Polygonal approximations of isosurfaces extracted from uniformly sampled volumes are increasing in size due to the availability of higher resolution imaging techniques. The large number of I primitives represented hinders the interactive exploration of the dataset. Though many solutions have been proposed to this problem, many require the creation of isosurfaces at multiple resolutions or the use of additional data structures, often hierarchical, to represent the volume. We propose a technique for adaptive isosurface extraction that is easy to implement and allows the user to decide the degree of adaptivity as well as the choice of isosurface extraction algorithm. Our method optimizes the extraction of the isosurface by warping the volume. In a warped volume, areas of importance (e.g. containing significant details) are inflated while unimportant ones are contracted. Once the volume is warped, any extraction algorithm can be applied. The extracted mesh is subsequently unwarped such that the warped areas are rescaled to their initial proportions. The resulting isosurface is represented by a mesh that is more densely sampled in regions decided as important. | false | false | [
"Laurent Balmelli",
"Christopher J. Morris 0001",
"Gabriel Taubin",
"Fausto Bernardini"
] | [] | [] | [] |
Vis | 2,002 | Volumetric shadows using splatting | 10.1109/VISUAL.2002.1183761 | This paper describes an efficient algorithm to model the light attenuation due to a participating media with low albedo. The light attenuation is modeled using splatting volume renderer for both the viewer and the light source. During the rendering, a 2D shadow buffer attenuates the light for each pixel. When the contribution of a footprint is added to the image buffer, as seen from the eye, we add the contribution to the shadow buffer, as seen from the light source. We have generated shadows for point lights and parallel lights using this algorithm. The shadow algorithm has been extended to deal with multiple light sources and projective textured lights. | false | false | [
"Caixia Zhang",
"Roger Crawfis"
] | [] | [] | [] |
Vis | 2,002 | XFastMesh: fast view-dependent meshing from external memory | 10.1109/VISUAL.2002.1183796 | We present a novel disk-based multiresolution triangle mesh data structure that supports paging and view-dependent rendering of very large meshes at interactive frame rates from external memory. Our approach, called XFastMesh, is based on a view-dependent mesh simplification framework that represents half-edge collapse operations in a binary hierarchy known as a merge-tree forest. The proposed technique partitions the merge-tree forest into so-called detail blocks, which consist of binary subtrees, that are stored on disk. We present an efficient external memory data structure and file format that stores all detail information of the multiresolution triangulation method using significantly less storage then previously reported approaches. Furthermore, we present a paging algorithm that provides efficient loading and interactive rendering of large meshes from external memory at varying and view-dependent level-of-detail. The presented approach is highly efficient both in terms of space cost and paging performance. | false | false | [
"Christopher DeCoro",
"Renato Pajarola"
] | [] | [] | [] |
InfoVis | 2,002 | A hybrid layout algorithm for sub-quadratic multidimensional scaling | 10.1109/INFVIS.2002.1173161 | Many clustering and layout techniques have been used for structuring and visualising complex data. This paper is inspired by a number of such contemporary techniques and presents a novel hybrid approach based upon stochastic sampling, interpolation and spring models. We use Chalmers' 1996 O(N/sup 2/) spring model as a benchmark when evaluating our technique, comparing layout quality and run times using data sets of synthetic and real data. Our algorithm runs in O(N/spl radic/N) and executes significantly faster than Chalmers' 1996 algorithm, whilst producing superior layouts. In reducing complexity and run time, we allow the visualisation of data sets of previously infeasible size. Our results indicate that our method is a solid foundation for interactive and visual exploration of data. | false | false | [
"Alistair Morrison",
"Greg Ross",
"Matthew Chalmers"
] | [] | [] | [] |
InfoVis | 2,002 | A space-optimized tree visualization | 10.1109/INFVIS.2002.1173152 | We describe a new method for the visualization of tree structured relational data. It can be used especially for the display of very large hierarchies in a 2-dimensional space. We discuss the advantages and limitations of current techniques of tree visualization. Our strategy is to optimize the drawing of trees in a geometrical plane and maximize the utilization of display space by allowing more nodes and links to be displayed at a limit screen resolution. We use the concept of enclosure to partition the entire display space into a collection of local regions that are assigned to all nodes in tree T for the display of their sub-trees and themselves. To enable the exploration of large hierarchies, we use a modified semantic zooming technique to view the detail of a particular part of the hierarchy at a time based on user's interest. Layout animation is also provided to preserve the mental map while the user is exploring the hierarchy by changing zoomed views. | false | false | [
"Quang Vinh Nguyen",
"Mao Lin Huang"
] | [] | [] | [] |
InfoVis | 2,002 | ACE: a fast multiscale eigenvectors computation for drawing huge graphs | 10.1109/INFVIS.2002.1173159 | We present an extremely fast graph drawing algorithm for very large graphs, which we term ACE (for Algebraic multigrid Computation of Eigenvectors). ACE exhibits an improvement of something like two orders of magnitude over the fastest algorithms we are aware of; it draws graphs of millions of nodes in less than a minute. ACE finds an optimal drawing by minimizing a quadratic energy function. The minimization problem is expressed as a generalized eigenvalue problem, which is rapidly solved using a novel algebraic multigrid technique. The same generalized eigenvalue problem seems to come up also in other fields, hence ACE appears to be applicable outside of graph drawing too. | false | false | [
"Yehuda Koren",
"Liran Carmel",
"David Harel"
] | [] | [] | [] |
InfoVis | 2,002 | Angular brushing of extended parallel coordinates | 10.1109/INFVIS.2002.1173157 | In this paper we present angular brushing for parallel coordinates (PC) as a new approach to highlighting rational data-properties, i.e., features which - in a non-separable way - depend on two data dimensions. We also demonstrate smooth brushing as an intuitive tool for specifying nonbinary degree-of-interest functions (for focus+context visualization). We also briefly describe our implementation as well as its application to the visualization of CFD data. | false | false | [
"Helwig Hauser",
"Florian Ledermann",
"Helmut Doleisch"
] | [] | [] | [] |
InfoVis | 2,002 | Arc diagrams: visualizing structure in strings | 10.1109/INFVIS.2002.1173155 | This paper introduces a new visualization method, the arc diagram, which is capable of representing complex patterns of repetition in string data. Arc diagrams improve over previous methods such as dotplots because they scale efficiently for strings that contain many instances of the same subsequence. This paper describes design and implementation issues related to arc diagrams and shows how they may be applied to visualize such diverse data as music, text, and compiled code. | false | false | [
"Martin Wattenberg"
] | [] | [] | [] |
InfoVis | 2,002 | Beamtrees: compact visualization of large hierarchies | 10.1109/INFVIS.2002.1173153 | Beamtrees are a new method for the visualization of large hierarchical data sets. Nodes are shown as stacked circular beams, such that both the hierarchical structure as well as the size of nodes are depicted. The dimensions of beams are calculated using a variation of the treemap algorithm. A small user study indicated that beamtrees are significantly more effective than nested treemaps and cushion treemaps for the extraction of global hierarchical information. | false | false | [
"Frank van Ham",
"Jarke J. van Wijk"
] | [] | [] | [] |
InfoVis | 2,002 | Building a visual database for example-based graphics generation | 10.1109/INFVIS.2002.1173143 | Example-based graphics generation systems automatically create new information visualizations by learning from existing graphic examples. As part of the effort on developing a general-purpose example-based generation system, we are building a visual database of graphic examples. In this paper, we address two main issues involved in constructing such a database: example selection and example modeling. As a result, our work offers three unique contributions: First, we build a visual database that contains a diverse collection of well-designed examples. Second, we develop a feature-based scheme to model all examples uniformly and accurately. Third, our visual database brings several important implications to the area of information visualization. | false | false | [
"Michelle X. Zhou",
"Min Chen",
"Ying Feng"
] | [] | [] | [] |
InfoVis | 2,002 | Case study: visualizing sets of evolutionary trees | 10.1109/INFVIS.2002.1173150 | We describe a visualization tool which allows a biologist to explore a large set of hypothetical evolutionary trees. Interacting with such a dataset allows the biologist to identify distinct hypotheses about how different species or organisms evolved, which would not have been clear from traditional analyses. Our system integrates a point-set visualization of the distribution of hypothetical trees with detail views of an individual tree, or of a consensus tree summarizing a subset of trees. Efficient algorithms were required for the key tasks of computing distances between trees, finding consensus trees, and laying out the point-set visualization. | false | false | [
"Nina Amenta",
"Jeff Klingner"
] | [] | [] | [] |
InfoVis | 2,002 | Demystifying venture capital investing | 10.1109/INFVIS.2002.1173162 | Since the crash of the dot.coms, investors have gotten a lot more careful with where they place their money. Now more than ever it becomes really important for venture capitalists (VCs) to monitor the state of the startups market and continually update their investment strategy to suit the rapidly changing market conditions. This paper presents three new visualization metaphors (Spiral Map, TimeTicker, and Double Histogram) for monitoring the startups market. While we are focusing on the VC domain, the visual metaphors developed are general and can be easily applied to other domains. | false | false | [
"Mei C. Chuah"
] | [] | [] | [] |
InfoVis | 2,002 | Display design for the eye and mind | 10.1109/INFVIS.2002.1173164 | Complex sets of numbers often can be effectively digested only after they are illustrated in charts, graphs or diagrams. However, some of these pictures are worth far less than the proverbial 1,000 words. If a visual display taxes the human perceptual, memory, or cognitive systems, it will be difficult to understand. This talk shows how facts about human information processing can guide one to design “articulate” graphics, which can be read easily and understood immediately. This information is organized into three general “maxims,” which in turn are used to organize sets of individual principles. Each of the principles is illustrated with “good” and “bad” displays taken from magazines, technical digests, books, newspapers, and other sources. The talk will conclude with some reflections about ways in which computational systems can take advantage of these principles, for example by providing no more and no less information than is relevant to the viewer's immediate concerns. | false | false | [
"Stephen M. Kosslyn"
] | [] | [] | [] |
InfoVis | 2,002 | Efficient cartogram generation: a comparison | 10.1109/INFVIS.2002.1173144 | Cartograms are a well-known technique for showing geography-related statistical information, such as population demographics and epidemiological data. The basic idea is to distort a map by resizing its regions according to a statistical parameter, but in a way that keeps the map recognizable. We deal with the problem of making continuous cartograms that strictly retain the topology of the input mesh. We compare two algorithms to solve the continuous cartogram problem. The first one uses an iterative relocation of the vertices based on scanlines. The second one is based on the Gridfit technique, which uses pixel-based distortion based on a quadtree-like data structure. | false | false | [
"Daniel A. Keim",
"Stephen C. North",
"Christian Panse",
"Jörn Schneidewind"
] | [] | [] | [] |
InfoVis | 2,002 | Graphical encoding for information visualization: an empirical study | 10.1109/INFVIS.2002.1173146 | Research in several areas provides scientific guidance for use of graphical encoding to convey information in an information visualization display. By graphical encoding we mean the use of visual display elements such as icon color, shape, size, or position to convey information about objects represented by the icons. Literature offers inconclusive and often conflicting viewpoints, including the suggestion that the effectiveness of a graphical encoding depends on the type of data represented. Our empirical study suggests that the nature of the users' perceptual task is more indicative of the effectiveness of a graphical encoding than the type of data represented. | false | false | [
"Lucy T. Nowell",
"Robert S. Schulman",
"Deborah Hix"
] | [] | [] | [] |
InfoVis | 2,002 | Interactive information visualization of a million items | 10.1109/INFVIS.2002.1173156 | Existing information visualization techniques are usually limited to the display of a few thousand items. This article describes new interactive techniques capable of handling a million items (effectively visible and manageable on screen). We evaluate the use of hardware-based techniques available with newer graphics cards, as well as new animation techniques and non-standard graphical features such as stereovision and overlap count. These techniques have been applied to two popular information visualizations: treemaps and scatter plot diagrams; but are generic enough to be applied to other 2D representations as well. | false | false | [
"Jean-Daniel Fekete",
"Catherine Plaisant"
] | [] | [] | [] |
InfoVis | 2,002 | Internet traffic: visualization, discovery, and very large displays | 10.1109/INFVIS.2002.1173140 | For a decade, the ruling common wisdom for Internet traffic held that it was everywhere bursty: over periods lasting tens of milliseconds to hundreds, the traffic was either much below its average rate or much above. In other words, the traffic was not smooth, not staying at all times close to its average. It was bursty on the cable running down a street, carrying the merged traffic of a small number of cable modem users in one section of a town. It was bursty on the core fiber of an Internet service provider, carrying the merged traffic of thousands of users from all over the country. The Internet was designed to accommodate the bursty traffic. The routers and switches that forward traffic from one place to the next were designed for burstiness, and Internet service providers allocated traffic loads on the devices based on an assumption of burstiness. Recently, it was discovered that the old common wisdom is not true. Visualization played a fundamental role in the discovery. The old wisdom held up for links with a small numbers of users. But as the number of users increases, the burstiness dissipates, and the traffic becomes smooth. Design of the high-load part of the Internet needs to be rethought. The old wisdom had persisted for high-load links because the databases of traffic measurements from them are immense, and the traffic measurements had not been studied in their fullest detail, which is necessary to see the smoothing. Visualization tools allowed the detail to be seen, and allowed the verification of a mathematical theory that predicts the smoothing. To see the detail, individual visual displays were created that take up an amount of virtual screen real estate measured in hundreds of pages. It is a simple idea: if you have a lot of data, and you want to see it in detail, you need a lot of space. What is needed now is a rich set of ideas and methods for navigating such very large displays. | false | false | [
"William S. Cleveland"
] | [] | [] | [] |
InfoVis | 2,002 | InterRing: an interactive tool for visually navigating and manipulating hierarchical structures | 10.1109/INFVIS.2002.1173151 | Radial, space-filling (RSF) techniques for hierarchy visualization have several advantages over traditional node-link diagrams, including the ability to efficiently use the display space while effectively conveying the hierarchy structure. Several RSF systems and tools have been developed to date, each with varying degrees of support for interactive operations such as selection and navigation. We describe what we believe to be a complete set of desirable operations on hierarchical structures. We then present InterRing, an RSF hierarchy visualization system that supports a significantly more extensive set of these operations than prior systems. In particular, InterRing supports multi-focus distortions, interactive hierarchy reconfiguration, and both semi-automated and manual selection. We show the power and utility of these and other operations, and describe our on-going efforts to evaluate their effectiveness and usability. | false | false | [
"Jing Yang 0001",
"Matthew O. Ward",
"Elke A. Rundensteiner"
] | [] | [] | [] |
InfoVis | 2,002 | Multiple foci drill-down through tuple and attribute aggregation polyarchies in tabular data | 10.1109/INFVIS.2002.1173158 | Information analysis often involves decomposing data into sub-groups to allow for comparison and identification of relationships. Breakdown Visualization provides a mechanism to support this analysis through user guided drill-down of polyarchical metadata. This metadata describes multiple hierarchical structures for organizing tuple aggregations and table attributes. This structure is seen in financial data, organizational structures, sport statistics, and other domains. A spreadsheet format enables comparison of visualizations at any level of the hierarchy. Breakdown Visualization allows users to drill-down a single hierarchy then pivot into another hierarchy within the same view. It utilizes a fix and move technique that allows users to select multiple foci for drill-down. | false | false | [
"Nathan Conklin",
"Sandeep Prabhakar",
"Chris North 0001"
] | [] | [] | [] |
InfoVis | 2,002 | Multiscale visualization using data cubes | 10.1109/INFVIS.2002.1173141 | Most analysts start with an overview of the data before gradually refining their view to be more focused and detailed. Multiscale pan-and-zoom systems are effective because they directly support this approach. However generating abstract overviews of large data sets is difficult, and most systems take advantage of only one type of abstraction: visual abstraction. Furthermore, these existing systems limit the analyst to a single zooming path on their data and thus a single set of abstract views. This paper presents: (1) a formalism for describing multiscale visualizations of data cubes with both data and visual abstraction, and (2) a method for independently zooming along one or more dimensions by traversing a zoom graph with nodes at different levels of detail. As an example of how to design multiscale visualizations using our system, we describe four design patterns using our formalism. These design patterns show the effectiveness of multiscale visualization of general relational databases. | false | false | [
"Chris Stolte",
"Diane Tang",
"Pat Hanrahan"
] | [
"BP"
] | [] | [] |
InfoVis | 2,002 | Process visualization with levels of detail | 10.1109/INFVIS.2002.1173149 | We demonstrate how we apply information visualization techniques to process monitoring. Virtual instruments are enhanced using history encoding instruments are capable of displaying the current value and the value from the near past. Multi-instruments are capable of displaying several data sources simultaneously. Levels of detail for virtual instruments are introduced where the screen area is inversely proportional to the information amount displayed. Furthermore the monitoring system is enhanced by using: 3D anchoring attachment of instruments to positions on a 3D model, collision avoidance a physically based spring model prevents instruments from overlapping, and focus+context rendering - giving the user a possibility to examine particular instruments in detail without loosing the context information. | false | false | [
"Kresimir Matkovic",
"Helwig Hauser",
"Reinhard Sainitzer",
"M. Eduard Gröller"
] | [] | [] | [] |
InfoVis | 2,002 | SpaceTree: supporting exploration in large node link tree, design evolution and empirical evaluation | 10.1109/INFVIS.2002.1173148 | We present a novel tree browser that builds on the conventional node link tree diagrams. It adds dynamic rescaling of branches of the tree to best fit the available screen space, optimized camera movement, and the use of preview icons summarizing the topology of the branches that cannot be expanded. In addition, it includes integrated search and filter functions. This paper reflects on the evolution of the design and highlights the principles that emerged from it. A controlled experiment showed benefits for navigation to already previously visited nodes and estimation of overall tree topology. | false | false | [
"Catherine Plaisant",
"Jesse Grosjean",
"Benjamin B. Bederson"
] | [] | [] | [] |
InfoVis | 2,002 | The illusion of perceived metric 3D structure | 10.1109/INFVIS.2002.1173147 | A large body of results on the characteristics of human spatial vision suggests that space perception is distorted. Recent studies indicate that the geometry of visual space is best understood as Affine. If this is the case, it has far reaching implications on how 3D visualizations can be successfully employed. For instance, all attempts to build visualization systems where users are expected to discover relations based on Euclidean distances or shapes will be ineffective. Because visualization can, and sometimes do, employ all possible types of depth information and because the results from vision research usually concentrates on one or two such types, three experiments were performed under near optimal viewing conditions. The aim of the experiments was twofold: To test whether the earlier findings generalize to optimal viewing conditions and to get a sense of the size of the error under such conditions. The results show that the findings do generalize and that the errors are large. The implications of these results for successful visualizations are discussed. | false | false | [
"Mats Lind",
"Geoffrey P. Bingham",
"Camilla Forsell"
] | [] | [] | [] |
InfoVis | 2,002 | Visual path analysis | 10.1109/INFVIS.2002.1173163 | We describe a system for analyzing the flow of traffic through Web sites. We decomposed the general path analysis problem into a set of distinct subproblems, and created a visual metaphor for analyzing each of them. Our system works off of multiple representations of the clickstream, and exposes the path extraction algorithms and data to the visual metaphors as Web services. We have combined the visual metaphors into a Web-based "path analysis portal" that lets the user easily switch between the different modes of analysis. | false | false | [
"Alan Keahey",
"Stephen G. Eick"
] | [] | [] | [] |
InfoVis | 2,002 | Visual unrolling of network evolution and the analysis of dynamic discourse | 10.1109/INFVIS.2002.1173160 | A new method for visualizing the class of incrementally evolving networks is presented. In addition to the intermediate states of the network it conveys the nature of the change between them by unrolling the dynamics of the network. Each modification is shown in a separate layer of a three-dimensional representation, where the stack of layers corresponds to a time line of the evolution. We focus on discourse networks as the driving application, but our method extends to any type of network evolving in similar ways. | false | false | [
"Ulrik Brandes",
"Steven R. Corman"
] | [] | [] | [] |
InfoVis | 2,002 | Visualization schemas for flexible information visualization | 10.1109/INFVIS.2002.1173142 | Relational databases provide significant flexibility to organize, store, and manipulate an infinite variety of complex data collections. This flexibility is enabled by the concept of relational data schemas, which allow data owners to easily design custom databases according to their unique needs. However, user interfaces and information visualizations for accessing and utilizing databases have not kept pace with this level of flexibility. This paper introduces the concept of visualization schemas, based on the Snap-Together Visualization model, which are analogous to relational data schemas. Visualization schemas enable users to rapidly construct customized multiple-view visualizations for databases in a similarly flexible fashion without programming. Since the design of appropriate visualizations for a given database depends on the data schema, visualization schemas are a natural analogy to the data schema concept. | false | false | [
"Chris North 0001",
"Nathan Conklin",
"Varun Saini"
] | [] | [] | [] |
InfoVis | 2,002 | Visualizing biosequence data using texture mapping | 10.1109/INFVIS.2002.1173154 | Data-mining of information by the process of pattern discovery in protein sequences has been predominantly algorithm based. We discuss a visualization approach, which uses texture mapping and blending techniques to perform visual data-mining on text data obtained from discovering patterns in protein sequences. This visual approach, investigates the possibilities of representing text data in three dimensions and provides new possibilities of representing more dimensions of information in text data visualization and analysis. We also present a generic framework derived from this visualization approach to visualize text in biosequence data. | false | false | [
"Praveen R. Thiagarajan",
"Guang R. Gao"
] | [] | [] | [] |
InfoVis | 2,002 | Visualizing data with bounded uncertainty | 10.1109/INFVIS.2002.1173145 | Visualization is a powerful way to facilitate data analysis, but it is crucial that visualization systems explicitly convey the presence, nature, and degree of uncertainty to users. Otherwise, there is a danger that data will be falsely interpreted, potentially leading to inaccurate conclusions. A common method for denoting uncertainty is to use error bars or similar techniques designed to convey the degree of statistical uncertainty. While uncertainty can often be modeled statistically, a second form of uncertainty, bounded uncertainty, can also arise that has very different properties than statistical uncertainty. Error bars should not be used for bounded uncertainty because they do not convey the correct properties, so a different technique should be used instead. We describe a technique for conveying bounded uncertainty in visualizations and show how it can be applied systematically to common displays of abstract charts and graphs. Interestingly, it is not always possible to show the exact degree of uncertainty, and in some cases it can only be displayed approximately. | false | false | [
"Christopher Olston",
"Jock D. Mackinlay"
] | [] | [] | [] |
EuroVis | 2,002 | A Continuous Skeletonization Method Based on Level Sets | 10.2312/VisSym/VisSym02/151-157 | A robust and efficient method in 2D and 3D for the calculation of skeletons for arbitrary objects is presented. The method is based on the calculation of the distance function with respect to the object boundary. This is combined, in a post processing step, with a new indicator to identify the skeleton, which coincides with the singularity set of the distance map. The indicator is defined as a suitable function of certain local momenta of this distance map and allows a robust and accurate computation of the distance from the skeleton set. This distance is then extended, again via the level set method, onto the whole space. Several applications in 2D and 3D are presented. | false | false | [
"Martin Rumpf",
"Alexandru C. Telea"
] | [] | [] | [] |
EuroVis | 2,002 | A Generic Solution for Hardware-Accelerated Remote Visualization | 10.2312/VisSym/VisSym02/087-094 | This paper presents a generic solution for hardware-accelerated remote visualization that works transparently for all OpenGL-based applications and OpenGL-based scene graphs. Universality is achieved by taking advantage of dynamic linking, efficient data transfer by means of VNC. The proposed solution does not require any modifications of existing applications and allows for remote visualization with different hardware architectures involved in the visualization process. The library's performance is evaluated using standard OpenGL example programs and by volume rendering substantial data sets. | false | false | [
"Simon Stegmaier",
"Marcelo Magallón",
"Thomas Ertl"
] | [] | [] | [] |
EuroVis | 2,002 | A Novel Approach To Vortex Core Region Detection | 10.2312/VisSym/VisSym02/217-225 | In this paper we present a simple and efficient vortex core region detection algorithm based on ideas derived from combinatorial topology. These ideas originated from Sperner's lemma, which by itself is of little value to detecting vortex cores. However, we take these ideas from the lemma and apply them in a point-based fashion to detecting vortex core regions. The resulting algorithms for both 2D and 3D are quite simple and very efficient compared to existing ones. We applied our algorithms to both numerically simulated and procedurally generated datasets to illustrate the efficacy of our approach. | false | false | [
"Ming Jiang 0005",
"Raghu Machiraju",
"David S. Thompson"
] | [] | [] | [] |
EuroVis | 2,002 | Adding a scalar value to texture-based vector field representations by local contrast analysis | 10.2312/VisSym/VisSym02/035-041 | Several algorithms can effectively represent vector fields by texture-based representations, visualizing at most all information on the field: direction, orientation, and local magnitude. An open problem still remains the mapping on textures of adjunctive information such as temperature, pressure, and so on, without using colors. This article addresses this issue by proposing a technique to add a scalar value denoting streamlines by means of different levels of contrast. Both streamline starting tones and the range of tones depend on the scalar value to be mapped; in this way, areas visualized by different contrast levels are represented. Two examples show the effectiveness of the proposed technique. | false | false | [
"Andrea Sanna",
"Claudio Zunino",
"Bartolomeo Montrucchio",
"Paolo Montuschi"
] | [] | [] | [] |
EuroVis | 2,002 | An Augmented Fast Marching Method for Computing Skeletons and Centerlines | 10.2312/VisSym/VisSym02/251-259 | We present a simple and robust method for computing skeletons for arbitrary planar objects and centerlines for 3D objects. We augment the Fast Marching Method (FMM) widely used in level set applications by computing the paramterized boundary location every pixel came from during the boundary evolution. The resulting parameter field is then thresholded to produce the skeleton branches created by boundary features of a given size. The presented algorithm is straightforward to implement, has low memory costs and short execution times, and is robust with respect to the used threshold and initial shape noisiness. The produced skeletons are very similar to the ones delivered by more complex algorithms. Various 2D and 3D applications are presented. | false | false | [
"Alexandru C. Telea",
"Jarke J. van Wijk"
] | [] | [] | [] |
EuroVis | 2,002 | An Evaluation of Information Visualization in Attention-Limited Environments | 10.2312/VisSym/VisSym02/211-216 | People often need to quickly access or maintain awareness of secondary information while busy with other primary tasks. Information visualizations provide rapid, effective access to information, but are generally designed to be examined by users as the primary focus of their attention. The goal of this research is to discover how to design information visualizations intended for the periphery and to understand how quickly and effectively people can interpret information visualizations while they are busily performing other tasks. We evaluated how several factors of a visualization (visual density, presence time, and secondary task type) impact people's abilities to continue with a primary task and to complete secondary tasks related to the visualization. Our results suggest that, with relaxed time pressure, reduced visual information density and a single well-defined secondary task, people can effectively interpret visualizations with minimal distraction to their primary task. | false | false | [
"Jacob P. Somervell",
"D. Scott McCrickard",
"Chris North 0001",
"Maulik Shukla"
] | [] | [] | [] |
EuroVis | 2,002 | An Open Toolkit for Prototyping Reverse Engineering Visualizations | 10.2312/VisSym/VisSym02/241-249 | Maintenance and evolution of complex software systems (such as mobile telephones) involves activities such as reverse engineering (RE) and software visualization. Although several RE tools exist, we found their architecture hard to adapt to the domain and problem specific requirements posed by our current practice in Nokia. In this paper, we present an open architecture which allows easy prototyping of RE data exploration and visualization scenarios for a large range of domain models. We pay special attention to the visual and interactive requirements of the reverse engineering process. We compare our toolkit with other existing reverse engineering visual tools and outline the differences. | false | false | [
"Alexandru C. Telea",
"Alessandro Maccari",
"Claudio Riva"
] | [] | [] | [] |
EuroVis | 2,002 | AUFLIC: An Accelerated Algorithm For Unsteady Flow Line Integral Convolution | 10.2312/VisSym/VisSym02/043-052 | UFLIC (Unsteady Flow Line Integral Convolution) is an effective texture synthesis technique to visualize unsteady flow with enhanced temporal coherence, but it is time-consuming to generate. This paper presents an accelerated algorithm, called AUFLIC (Accelerated UFLIC), to speed up the UFLIC generation. Our algorithm saves, re-uses, and updates pathlines in the value scattering processes. A flexible seeding strategy is introduced so that a seed particle may be directly extracted from the previous scattering processes to make best use of the saved pathline so as to reduce computationally expensive pathline integration calculations. A dynamic activation-deactivation scheme is employed to maintain the fewest necessary pathlines. Avoiding excessive pathlines achieves acceleration and nearly-constant memory consumption. With very low memory cost, AUFLIC cuts UFLIC generation time nearly in half without any image quality degradation. | false | false | [
"Zhanping Liu",
"Robert J. Moorhead II"
] | [] | [] | [] |
EuroVis | 2,002 | Bag-of-Particles as a Deformable Model | 10.2312/VisSym/VisSym02/141-150 | We present an interactive, physically-based, elastically deformable model using a particle system to model surfaces with interior volumes that can be haptically felt. Oriented particles used in existing surface-only models, and unoriented particles used in volume-only simulations are combined to form a bag-of-particles. Multiple species of surface and volume particles, coupled with prede£ned interspecies parameters, determine the elastic properties of a bag. Starting with an object represented as a 3D voxel bitmap of connected components, the gradient of its distance map gives a vector £eld, or gradient map, that captures the static shape of an object and provides shape-maintaining forces. The gradient map enables the user to de£ne the geometry of the simulated objects, and provides feedback reaction forces allowing a user to feel the model. A bag-of-particles model can simulate several objects in the same scene, as well as objects composed of different materials, such as organs with multiple tissue types. We demonstrate the bag-of-particles approach using a number of different data sources, and apply it to modeling myocardium dynamics. | false | false | [
"David J. Stahl Jr.",
"Norberto Ezquerra",
"Greg Turk"
] | [] | [] | [] |
EuroVis | 2,002 | Best Quadratic Spline Approximation for Hierarchical Visualization | 10.2312/VisSym/VisSym02/133-140 | We present a method for hierarchical data approximation using quadratic simplicial elements for domain decomposition and field approximation. Higher-order simplicial elements can approximate data better than linear elements. Thus, fewer quadratic elements are required to achieve similar approximation quality. We use quadratic basis functions and compute best quadratic simplicial spline approximations that are C0-continuous everywhere. We adaptively refine a simplicial approximation by identifying and bisecting simplicial elements with largest errors. It is possible to store multiple approximation levels of increasing quality. We have tested the suitability and efficiency of our hierarchical data approximation scheme by applying it to several data sets. | false | false | [
"David F. Wiley",
"Henry R. Childs",
"Bernd Hamann",
"Kenneth I. Joy",
"Nelson L. Max"
] | [] | [] | [] |
EuroVis | 2,002 | Cell-Based First-Hit Ray Casting | 10.2312/VisSym/VisSym02/077-086 | Cell-based first-hit ray casting is a new technique for fast perspective volume visualization. This technique, based on the well known ray casting algorithm, performs iso-surfacing and supports interactive threshold adjustment. It is accelerated by the reduction of average ray path lengths to only a few steps per pixel. The volume is divided into cubic sub volumes. Each sub volume that is intersected by an iso-surface is projected to the image plane. A local ray casting step within the sub volume is performed for each pixel covered by the projection. Cell-based first-hit ray casting is perfectly suited whenever fast perspective iso-surfacing is required. This paper describes the basic algorithm, presents possible optimizations and evaluates the performance of the algorithm for one specific application, the post-implantation assessment of endovascular stent placement. It will be shown that the algorithm, though executed on a single processor machine without any hardware acceleration, performs well for view points inside as well as outside the stented blood vessel and significantly outperforms an optimized, yet more conventional ray casting technique. | false | false | [
"André Neubauer 0002",
"Lukas Mroz",
"Helwig Hauser",
"Rainer Wegenkittl"
] | [] | [] | [] |
EuroVis | 2,002 | Comparison of Morphological Pyramids for Multiresolution MIP Volume Rendering | 10.2312/VisSym/VisSym02/061-070 | We recently proposed a multiresolution representation for maximum intensity projection (MIP) volume rendering based on morphological adjunction pyramids which allow progressive refinement and have the property of perfect reconstruction. In this algorithm the pyramidal analysis and synthesis operators are composed of morphological erosion and dilation, combined with dyadic downsampling for analysis and dyadic upsampling for synthesis. Here we introduce an alternative pyramid scheme in which a morphological opening instead of an erosion is used for pyramidal analysis. As a result, the approximation accuracy when rendering from higher levels of the pyramid is improved. | false | false | [
"Jos B. T. M. Roerdink"
] | [] | [] | [] |
EuroVis | 2,002 | Direct Volume Rendering of Photographic Volumes Using Multi-Dimensional Color-Based Transfer Functions | 10.2312/VisSym/VisSym02/115-124 | Traditionally, volume rendering of medical data has been comprised of transfer functions that map a scalar value, usually a MRI or CT intensity, to an opacity. Corresponding color maps are either selected regardless of the actual physical color of the volume (i.e. greyscale) or predetermined as in photographic volumes. Rarely has the voxel color been used as a means to define the associated opacity value. By using transfer functions that map multi-channel color values(RGB or CIE L*u*v*) to opacity, we can generate compelling and informative renderings that provide consistent boundary extraction throughout the volume. We present renderings of the Visible Human photographic volume using multi-dimensional color-based transfer functions. These functions were constructed by using gradient boundary enhancement techniques in conjunction with volume illustration techniques and incorporating the first and second directional derivatives along the gradient direction. We empirically compare the effectiveness of using the color-based transfer functions and discuss their applications and potential for future development. | false | false | [
"Christopher J. Morris 0001",
"David S. Ebert"
] | [] | [] | [] |
EuroVis | 2,002 | Feature-Preserving Volume Filtering | 10.2312/VisSym/VisSym02/105-114 | In this paper a feature-preserving volume filtering method is presented. The basic idea is to minimize a three-component global error function penalizing the density and gradient errors and the curvature of the unknown filtered function. The optimization problem leads to a large linear equation system defined by a sparse coefficient matrix. We will show that such an equation system can be efficiently solved in frequency domain using fast Fourier transformation (FFT). For the sake of clarity, first we illustrate our method on a 2D example which is a dedithering problem. Afterwards the 3D extension is discussed in detail since we propose our method mainly for volume filtering. We will show that the 3D version can be efficiently used for elimination of the typical staircase artifacts of direct volume rendering without losing fine details. Unlike local filtering techniques, our novel approach ensures a⋅global smoothing effect. Previous global 3D methods are restricted to binary volumes or segmented iso-surfaces and they are based on area minimization of one single reconstructed surface. In contrast, our method is a general volume-filtering technique, implicitly smoothing all the iso-surfaces at the same time. Although the strength of the presented algorithm is demonstrated on a specific 2D and a specific 3D application, it is considered as a general mathematical tool for processing images and volumes. | false | false | [
"László Neumann",
"Balázs Csébfalvi",
"Ivan Viola",
"Matej Mlejnek",
"M. Eduard Gröller"
] | [] | [] | [] |
EuroVis | 2,002 | Interactive Previewing for Transfer Function Specification in Volume Rendering | 10.2312/VisSym/VisSym02/071-076 | This paper presents a new technique for supplying meaningful visual feedback during direct volume rendering transfer function specification. The technique uses meta-data calculated during a pre-processing step to generate interactively an approximate volume rendering that is voxel-registered with a single user-selected slice. Because of the registration, this preview can easily be alpha-blended with a grey-scale image of the data that is being volume rendered. In this way, the user gets real-time visual feedback on her transfer function specification with regards to both the expected composited optical properties and the "fidelity" (how closely the rendering matches the original data) of the resulting rendering. | false | false | [
"Charl P. Botha",
"Frits H. Post"
] | [] | [] | [] |
EuroVis | 2,002 | Interactive Visualization and Steering of CFD Simulations | 10.2312/VisSym/VisSym02/025-034 | We describe a system that supports real-time interactive visualization of computational fluid dynamics (CFD) simulations. The system allows a user to place and manipulate visualization primitives, such as isolines and streamlines, during an ongoing simulation process. A user can interactively select and designate regions of the computational mesh for refinement as the simulation progresses, perform remeshing, and see the effects of the refinement on the simulation in real time. The system is being used for the study of two open problems in compressible fluid dynamics. We can interactively explore solutions as they are computed, identify flow field regions containing features of interest, and refine the grid in those regions in order to obtain a better result locally. The ability to visualize "live" data, and to make changes to the computational setup in real time, has helped us to understand the underlying fundamental CFD simulation issues of these problems in shorter times than would otherwise have been possible. | false | false | [
"Oliver Kreylos",
"Allen M. Tesdall",
"B. Hamanny",
"John K. Hunter",
"Kenneth I. Joy"
] | [] | [] | [] |
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