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 |
|---|---|---|---|---|---|---|---|---|---|---|
EuroVis | 2,004 | Efficient Display of Background Objects for Virtual Endoscopy using Flexible First-Hit Ray Casting | 10.2312/VisSym/VisSym04/301-310 | Many applications of virtual endoscopy require the display of background objects behind the semi-transparent surface of the investigated organ. This paper deals with pre-processing and visualization of background objects for virtual endoscopy. A new first-hit ray casting technique for efficient perspective iso-surfacing of arbitrarily selected objects of interest is described: Visualization is performed without the use of dedicated hardware or data structures limiting flexibility (e.g., polygonal meshes or distance fields). The speedup is gained by exploiting inter-pixel coherency and by finding a near-optimal compromise between reduction of ray-tracking distances and limitation of the administrational cost associated with this reduction. The algorithm was developed by enhancing the previously published cell-based first-hit ray casting algorithm. This paper describes the original algorithm and explains the extensions needed to achieve interactive rendering of background objects. | false | false | [
"André Neubauer 0002",
"Marie-Thérèse Forster",
"Rainer Wegenkittl",
"Lukas Mroz",
"Katja Bühler"
] | [] | [] | [] |
EuroVis | 2,004 | Efficient Isosurface Tracking Using Precomputed Correspondence Table | 10.2312/VisSym/VisSym04/283-292 | Feature tracking is a useful method for visualizing and analyzing time-varying scalar fields. It allows scientists to focus on regions of interest and track their evolution and interaction over time. To allow the user to freely explore the data set, features must be tracked in an efficient manner. In this paper, we present an efficient time-varying isosurface tracking algorithm. Unlike the previous algorithms which compute the corresponding isosurface components in the adjacent time steps by performing expensive computation at run time, our algorithm can rapidly identify corresponding isosurfaces by performing simple table lookup operations. This table, called the correspondence lookup table, can be computed at a preprocessing stage. The idea behind our approach is that the correspondence relationship can only change at critical isovalues in R3 or R4 and remains unchanged between adjacent pairs of critical isovalues. With our algorithm, isosurfaces can be tracked in an efficient manner with minimal overhead. | false | false | [
"Guangfeng Ji",
"Han-Wei Shen"
] | [] | [] | [] |
EuroVis | 2,004 | Generalized Distance Transforms and Skeletons in Graphics Hardware | 10.2312/VisSym/VisSym04/221-230 | We present a framework for computing generalized distance transforms and skeletons of two-dimensional objects using graphics hardware. Our method is based on the concept of footprint splatting. Combining different splats produces weighted distance transforms for different metrics, as well as the corresponding skeletons and Voronoi diagrams. We present a hierarchical acceleration scheme and a subdivision scheme that allows visualizing the computed skeletons with subpixel accuracy in real time. Our splatting approach allows one to easily change all the metric parameters, treat any 2D boundaries, and easily produce both DTs and skeletons. We illustrate the method by several examples. | false | false | [
"Robert Strzodka",
"Alexandru C. Telea"
] | [] | [] | [] |
EuroVis | 2,004 | Graph Drawing by Subspace Optimization | 10.2312/VisSym/VisSym04/065-074 | We show a novel approach for accelerating the computation of graph drawing algorithms. The method is based on the notion that we can find a subspace with a relatively low dimensionality that captures the "nice" layouts of the graph. This way each axis of the drawing is a linear combination of a few basis vectors, instead of being an arbitrary vector in Rn (n is the number of nodes). We describe ways of constructing these basis vectors and also algorithms for optimizing the graph drawing in the resulting subspace. | false | false | [
"Yehuda Koren"
] | [] | [] | [] |
EuroVis | 2,004 | High-Quality Lighting for Pre-Integrated Volume Rendering | 10.2312/VisSym/VisSym04/025-034 | Pre-integrated volume rendering is an effective technique for generating high-quality visualizations. The precomputed lookup tables used by this method are slow to compute and can not include truly pre-integrated lighting due to space constraints. The lighting for pre-integrated rendering is therefore subject to the same sampling artifacts as in standard volume rendering. We propose methods to speed up lookup table generation and minimize lighting artifacts. The incremental subrange integration method we describe allows interactive lookup table generation in O(n2) time without the need for approximation or hardware assistance. The interpolated preintegrated lighting algorithm eliminates discontinuities by linearly interpolating illumination along the view direction. Both methods are applicable to any pre-integrated rendering method, including cell projection, ray casting, and hardware-accelerated algorithms. | false | false | [
"Eric B. Lum",
"Brett Wilson",
"Kwan-Liu Ma"
] | [] | [] | [] |
EuroVis | 2,004 | Illustrating Surfaces in Volume | 10.2312/VisSym/VisSym04/009-016 | This paper presents a novel framework for illustrating surfaces in a volume. Surfaces are illustrated by drawing only feature lines, such as silhouettes, valleys, ridges, and surface hatching strokes, and are embedded in volume renderings. This framework promises effective illustration of both surfaces and volumes without occluding or cluttering each other. A two-step approach has been taken: the first step depicts surfaces; the second step performs volume rendering, at the same time embedding surfaces from the first step.
We introduce Procedurally Perturbed Image Processing (PIP), a new method for enhancing both feature detection and depiction of surfaces. We also present implementation strategies, especially those leveraging modern graphics hardware, for delivering an interactive rendering system. Our implementation results have shown that this mixed form of rendering improves volume visualization and is efficient. | false | false | [
"Xiaoru Yuan",
"Baoquan Chen"
] | [] | [] | [] |
EuroVis | 2,004 | Interaction Spaces in Data and Information Visualization | 10.2312/VisSym/VisSym04/137-146 | User interaction plays an integral part in the effective visualization of data and information. Typical interaction operations include navigation, selection, and distortion. A problem that can occur when these operations are speci£ed using direct manipulation is determining which object or space is the focus of the interaction. In some operations the user wants to indicate a region of an image, while in others the focus might be the data being projected or the surface upon which the projection is occurring. In this paper we attempt to identify a complete list of spaces within which interactive operations can occur in data and information visualization. These interaction spaces help disambiguate the focus of interactive operations, and their study can potentially reveal new and powerful methods for supporting the visual exploration process. We de£ne the distinctions between the spaces and provide examples of interactions within each space. | false | false | [
"Matthew O. Ward",
"Jing Yang 0001"
] | [] | [] | [] |
EuroVis | 2,004 | Interactive High Quality Trimmed NURBS Visualization Using Appearance Preserving Tessellation | 10.2312/VisSym/VisSym04/211-220 | Trimmed NURBS models are the standard representation used in CAD/CAM systems and accurate visualization of large trimmed NURBS models at interactive frame rates is of great interest for industry. To visualize the quality of a surface several techniques like isophotes, reflection lines, etc. are used. Most existing approaches transform the NURBS surfaces into a fine polygonal representation and build static levels of detail from this representation. This polygonal approximation together with its normals are adjusted in a semi-automatic procedure to achieve the desired visual fidelity during visualization. Since this approach allows only for a fixed maximum accuracy and does not support deformable models, another more recent approach is to keep the NURBS representation and generate view-dependent LODs on the fly up to the currently required preciseness.
However, so far this approach took only into account the geometric error of an approximation and thus neglected the various illumination artifacts introduced by the chosen (possibly view-dependent) triangulation. Although this problem can be solved by using normal maps, the resolution of the normal maps again limits the accuracy. Furthermore, the normal map generation requires a preprocessing step which prevents the support of deformable NURBS models. In this paper we present a novel automatic tessellation algorithm that considers the illumination artifacts and is well suited both for the generation of static and dynamic LOD schemes with guaranteed visual fidelity. Our new method is also capable of high quality visualization of further attributes like curvature, temperature, etc. on surfaces with little or no modification. | false | false | [
"Michael Guthe",
"Ákos Balázs",
"Reinhard Klein"
] | [] | [] | [] |
EuroVis | 2,004 | Interactive Treemaps With Detail on Demand to Support Information Search in Documents | 10.2312/VisSym/VisSym04/121-128 | This paper addresses the issue of how information visualization techniques can be used to assist full-text search in electronic documents. Our approach supports multiple term queries with interactive treemaps. We use a treemap to visualize the basic structure of the document and exploit color coding to show the distribution of query terms on various levels of the hierarchy. Furthermore, we include filtering techniques to concentrate on those parts of the structure that actually contain the requested information, and, finally provide interactive tools to give access to detailed information whenever the user wishes. | false | false | [
"Stefan Schlechtweg",
"Petra Schulze-Wollgast",
"Heidrun Schumann"
] | [] | [] | [] |
EuroVis | 2,004 | Interactively Visualizing Procedurally Encoded Scalar Fields | 10.2312/VisSym/VisSym04/035-044 | While interactive visualization of rectilinear gridded volume data sets can now be accomplished using texture mapping hardware on commodity PCs, interactive rendering and exploration of large scattered or unstructured data sets is still a challenging problem. We have developed a new approach that allows the interactive rendering and navigation of procedurally-encoded 3D scalar fields by reconstructing these fields on PC class graphics processing units. Since the radial basis functions (RBFs) we use for encoding can provide a compact representation of volumetric scalar fields, the large grid/mesh traditionally needed for rendering is no longer required and ceases to be a data transfer and computational bottleneck during rendering. Our new approach will interactively render RBF encoded data obtained from arbitrary volume data sets, including both structured volume models and unstructured scattered volume models. This procedural reconstruction of large data sets is flexible, extensible, and can take advantage of the Moore's Law cubed increase in performance of graphics hardware. | false | false | [
"Yun Jang",
"Manfred Weiler",
"Matthias Hopf",
"Jingshu Huang",
"David S. Ebert",
"Kelly P. Gaither",
"Thomas Ertl"
] | [] | [] | [] |
EuroVis | 2,004 | Isosurface Computation Made Simple | 10.2312/VisSym/VisSym04/293-300 | This paper presents a simple approach for rendering isosurfaces of a scalar field. Using the vertex programming capability of commodity graphics cards, we transfer the cost of computing an isosurface from the Central Processing Unit (CPU), running the main application, to the Graphics Processing Unit (GPU), rendering the images. We consider a tetrahedral decomposition of the domain and draw one quadrangle (quad) primitive per tetrahedron. A vertex program transforms the quad into the piece of isosurface within the tetrahedron (see Figure 2). In this way, the main application is only devoted to streaming the vertices of the tetrahedra from main memory to the graphics card. For adaptively refined rectilinear grids, the optimization of this streaming process leads to the definition of a new 3D space-filling curve, which generalizes the 2D Sierpinski curve used for efficient rendering of triangulated terrains. We maintain the simplicity of the scheme when constructing view-dependent adaptive refinements of the domain mesh. In particular, we guarantee the absence of T-junctions by satisfying local bounds in our nested error basis. The expensive stage of fixing cracks in the mesh is completely avoided. We discuss practical tradeoffs in the distribution of the workload between the application and the graphics hardware. With current GPU's it is convenient to perform certain computations on the main CPU. Beyond the performance considerations that will change with the new generations of GPU's this approach has the major advantage of avoiding completely the storage in memory of the isosurface vertices and triangles. | false | false | [
"Valerio Pascucci"
] | [] | [] | [] |
EuroVis | 2,004 | Medical Applications of Multi-field Volume Rendering and VR Techniques | 10.2312/VisSym/VisSym04/249-254 | This paper reports on a new approach for visualizing multi-field MRI or CT datasets in an immersive environment with medical applications. Multi-field datasets combine multiple scanning modalities into a single 3D, multivalued, dataset. In our approach, they are classified and rendered using real-time hardware accelerated volume rendering, and displayed in a hybrid work environment, consisting of a dual power wall and a desktop PC. For practical reasons in this environment, the design and use of the transfer functions is subdivided into two steps, classification and exploration. The classification step is done at the desktop, taking advantage of the 2D mouse as a high accuracy input device. The exploration process takes place on the powerwall. We present our new approach, describe the underlying implementation issues, report on our experiences with different immersive environments, and suggest ways it can be used for collaborative medical diagnosis and treatment planning. | false | false | [
"Joe Kniss",
"Jürgen P. Schulze",
"Uwe Wössner",
"Peter Winkler 0004",
"Ulrich Lang 0002",
"Charles D. Hansen"
] | [] | [] | [] |
EuroVis | 2,004 | Meshless Isosurface Generation from Multiblock Data | 10.2312/VisSym/VisSym04/273-282 | We propose a meshless method for the extraction of high-quality continuous isosurfaces from volumetric data represented by multiple grids, also called "multiblock" data sets. Multiblock data sets are commonplace in computational mechanics applications. Relatively little research has been performed on contouring multiblock data sets, particularly when the grids overlap one another. Our algorithm proceeds in two steps. In the first step, we determine a continuous interpolant using a set of locally defined radial basis functions (RBFs) in conjunction with a partition of unity method to blend smoothly between these functions. In the second step, we extract isosurface geometry by sampling points on Marching Cubes triangles and projecting these point samples onto the isosurface defined by our interpolant. A surface splatting algorithm is employed for visualizing the resulting point set representing the isosurface. Because of our method's generality, it inherently solves the "crack problem" in isosurface generation. Results using a set of synthetic data sets and a discussion of practical considerations are presented. The importance of our method is that it can be applied to arbitrary grid data regardless of mesh layout or orientation. | false | false | [
"Christopher S. Co",
"Serban D. Porumbescu",
"Kenneth I. Joy"
] | [] | [] | [] |
EuroVis | 2,004 | Occlusion Culling for Sub-Surface Models in Geo-Scientific Applications | 10.2312/VisSym/VisSym04/267-272 | Modern graphics cards support occlusion culling in hardware. We present a three pass algorithm, which makes efficient use of this feature. Our geo-scientific sub-surface data sets consist typically of a set of high resolution height fields, polygonal objects, and volume slices and lenses. For each height field, we compute a low and high resolution version in a pre-process and divide both into sets of corresponding tiles. For each tile and for the polygonal objects, the first rendering pass computes a z-buffer image using the low resolution tiles, the polygonal objects and the non-transparent volume objects. During the second pass, we render the same objects against the z-buffer of the first pass while submitting an occlusion query with each object. The third pass reads this occlusion information back from the graphics hardware and renders only those high resolution objects, for which the corresponding low resolution objects were not completely occluded. To avoid fill rate bottle necks, the first two passes may be rendered to a low resolution window. Our implementation shows frame rate improvements for all test cases while introducing only a small overhead and no or hardly noticeable errors. Our non-conservative approach does not require front to back sorting and it works for dynamic scenes. | false | false | [
"John Plate",
"Anselm Grundhöfer",
"Benjamin Schmidt",
"Bernd Fröhlich 0001"
] | [] | [] | [] |
EuroVis | 2,004 | Ray Casting Curved-Quadratic Elements | 10.2312/VisSym/VisSym04/201-210 | We present a method for ray casting curved-quadratic elements in 3D. The advantages of this approach is that a curved element can be directly visualized. Conventionally, higher-order elements are tessellated with several linear elements so that standard visualization techniques can be applied to the linear elements. Our method primarily focuses on how to find an approximation to the intersection between a ray and a curved-quadratic element. Once this approximation is found, conventional accumulation and color mapping techniques can be applied to the approximation to produce a volumetric visualization of the element. A cutting plane implementation is also shown that leverages the ray casting technique. | false | false | [
"David F. Wiley",
"Henry R. Childs",
"Bernd Hamann",
"Kenneth I. Joy"
] | [] | [] | [] |
EuroVis | 2,004 | Shape-Embedded-Histograms for Visual Data Mining | 10.2312/VisSym/VisSym04/055-064 | Scatterplots are widely used in exploratory data analysis and class visualization. The advantages of scatterplots are that they are easy to understand and allow the user to draw conclusions about the attributes which span the projection screen. Unfortunately, scatterplots have the overplotting problem which is especially critical when high-dimensional data are mapped to low-dimensional visualizations. Overplotting makes it hard to detect the structure in the data, such as dependencies or areas of high density.
In this paper we show that by extending the concept of Pixel Validity (1) the problem of overplotting or occlusion can be avoided and (2) the user has the possibility to see information about an additional third variable. In our extension of the Pixel Validity concept, we summarize the data which are projected onto a given region by generating a histogram over the required attribute. This is then embedded in the visualization by a pixel-based technique. | false | false | [
"Amihood Amir",
"Reuven Kashi",
"Daniel A. Keim",
"Nathan S. Netanyahu",
"Markus Wawryniuk"
] | [] | [] | [] |
EuroVis | 2,004 | Software Landscapes: Visualizing the Structure of Large Software Systems | 10.2312/VisSym/VisSym04/261-266 | Modern object-oriented programs are hierarchical systems with many thousands of interrelated subsystems. Visualization helps developers to better comprehend these large and complex systems. This paper presents a three-dimensional visualization technique that represents the static structure of object-oriented programs using landscape-like distributions of three-dimensional objects on a two-dimensional plane. The familiar landscape methaphor facilitates intuitive navigation and comprehension. The visual complexity is reduced by adjusting the transparency of object surfaces to the distance of the viewpoint. An approach called Hierarchical Net is proposed for a clear representation of the relationsships between the subsystems. | false | false | [
"Michael Balzer",
"Andreas Noack",
"Oliver Deussen",
"Claus Lewerentz"
] | [] | [] | [] |
EuroVis | 2,004 | Superquadric tensor glyphs | 10.2312/VisSym/VisSym04/147-154 | Tensor field visualization is a challenging task due in part to the multi-variate nature of individual tensor samples. Glyphs convey tensor variables by mapping the tensor eigenvectors and eigenvalues to the orientation and shape of a geometric primitive, such as a cuboid or ellipsoid. Though widespread, cuboids and ellipsoids have problems of asymmetry and visual ambiguity. Cuboids can display misleading orientation for tensors with underlying rotational symmetry. Ellipsoids differing in shape can be confused, from certain viewpoints, because of similarities in profile and shading. This paper addresses the problems of asymmetry and ambiguity with a new tunable continuum of glyphs based on superquadric surfaces. Superquadric tensor glyphs enjoy the necessary symmetry properties of ellipsoids, while also imitating cuboids and cylinders to better convey shape and orientation, where appropriate. The new glyphs are demonstrated on fields of diffusion tensors from the human brain. | false | false | [
"Gordon L. Kindlmann"
] | [] | [] | [] |
EuroVis | 2,004 | Surface Techniques for Vortex Visualization | 10.2312/VisSym/VisSym04/155-164 | This paper presents powerful surface based techniques for the analysis of complex flow fields resulting from CFD simulations. Emphasis is put on the examination of vortical structures. An improved method for stream surface computation that delivers accurate results in regions of intricate flow is presented, along with a novel method to determine boundary surfaces of vortex cores. A number of surface techniques are presented that aid in understanding the flow behavior displayed by these surfaces. Furthermore, a scheme for phenomenological extraction of vortex core lines using stream surfaces is discussed and its accuracy is compared to one of the most established standard techniques. | false | false | [
"Christoph Garth",
"Xavier Tricoche",
"Tobias Salzbrunn",
"Tom Bobach",
"Gerik Scheuermann"
] | [] | [] | [] |
EuroVis | 2,004 | Techniques for Visualizing Multi-Valued Flow Data | 10.2312/VisSym/VisSym04/165-172 | In this paper we discuss several techniques to display multiple scalar distributions within an image depicting a 2D flow field. We first address how internal contrast and mean luminance can effectively be used to represent a scalar distribution in addition to an underlying flow field. Secondly, we expand upon a current technique to more effectively use luminance ramps over dense streamlines to represent direction of flow. Lastly, we present a new method, based on embossing, to encode the out-of-plane component of a 3D vector field defined over a 2D domain. Throughout this paper, we limit our focus to the visualization of steady flows. | false | false | [
"Timothy Urness",
"Victoria Interrante",
"Ellen Longmire",
"Ivan Marusic",
"Bharathram Ganapathisubramani"
] | [] | [] | [] |
EuroVis | 2,004 | Texture-Based Flow Visualization on Isosurfaces | 10.2312/VisSym/VisSym04/085-090 | Isosurfacing, by itself, is a common visualization technique for investigating 3D vector fields. Applying texturebased flow visualization techniques to isosurfaces provides engineers with even more insight into the characteristics of 3D vector fields. We apply a method for producing dense, texture-based representations of flow on isosurfaces. It combines two well know scientific visualization techniques, namely iso-surfacing and texture-based flow visualization, into a useful hybrid approach. The method is fast and can generate dense representations of flow on isosurfaces with high spatio-temporal correlation at 60 frames per second. The method is applied in the context of CFD simulation data, namely, the investigation of a common swirl flow pattern and the visualization of blood flow. | false | false | [
"Robert S. Laramee",
"Jürgen Schneider",
"Helwig Hauser"
] | [] | [] | [] |
EuroVis | 2,004 | TimeHistograms for Large, Time-Dependent Data | 10.2312/VisSym/VisSym04/045-054 | Histograms are a very useful tool for data analysis, because they show the distribution of values over a data dimension. Many data sets in engineering (like computational fluid dynamics, CFD), however, are time-dependent. While standard histograms can certainly show such data sets, they do not account for the special role time plays in physical processes and our perception of the world.
We present TimeHistograms, which are an extension to standard histograms that take time into account. In several 2D and 3D views, the data is presented in different ways that allow the user to understand different aspects of the temporal development of a dimension. A number of interaction techniques are also provided to make best use of the display, and to allow the user to brush in the histograms. | false | false | [
"Robert Kosara",
"Fabian Bendix",
"Helwig Hauser"
] | [] | [] | [] |
EuroVis | 2,004 | Visual Component Analysis | 10.2312/VisSym/VisSym04/129-136 | We propose to integrate information visualization techniques with factor analysis. Specifically, a principal direction derived from a principal component analysis (PCA) of the data is displayed together with the data in a scatterplot matrix. The direction can be adjusted to coincide with visual trends in the data. Projecting the data onto the orthogonal subspace allows determining the next direction. The set of directions identified in this way forms an orthogonal space, which represents most of the variation in the data. We call this process visual component analysis (VCA). Furthermore, it is quite simple to integrate VCA with clustering. The user fits poly-lines to the displayed data, and the poly-lines implicitly define clusters. Per-cluster projection leads to the definition of per-cluster components. | false | false | [
"Wolfgang Müller 0004",
"Marc Alexa"
] | [] | [] | [] |
EuroVis | 2,004 | Visual Triangulation of Network-Based Phylogenetic Trees | 10.2312/VisSym/VisSym04/075-084 | Phylogenetic trees are built by examining differences in the biological traits of a set of species. An example of such a trait is a biological network such as a metabolic pathway, common to all species but with subtle differences in each. Phylogenetic trees of metabolic pathways represent multiple aspects of similarity and hypothetical evolution in a single, yet complex structure that is difficult to understand and interpret. We present a visualization method that facilitates analysis of such structures by presenting multiple coordinated perspectives simultaneously. Each of these perspectives constitutes a useful visualization in its own right, but it is only together that they unfold their full explorative power. | false | false | [
"Ulrik Brandes",
"Tim Dwyer",
"Falk Schreiber"
] | [] | [] | [] |
EuroVis | 2,004 | Visualization For Public-Resource Climate Modeling | 10.2312/VisSym/VisSym04/103-108 | Climateprediction.net aims to harness the spare CPU cycles of a million individual users' PCs to run a massive ensemble of climate simulations using an up-to-date, full-scale 3D atmosphere-ocean climate model. Although it has many similarities with other public-resource computing projects, it is distinguished by the complexity of its computational task, its system demands and the level of participant interaction, data volume and analysis procedures. For simulations running on individual PCs, there is a requirement for visualizations that are compelling and readily grasped, since most users will be interested in the output from the model, but will have a limited level of scientific experience. This paper describes the design and implementation of these visualizations. | false | false | [
"J. P. R. B. Walton",
"D. Frame",
"D. A. Stainforth"
] | [] | [] | [] |
EuroVis | 2,004 | Visualization of anatomic tree structures with convolution surfaces | 10.2312/VisSym/VisSym04/311-320 | We present a method for visualizing anatomic tree structures, such as vasculature and bronchial trees based on clinical CT- or MR data. The vessel skeleton as well as the diameter information per voxel serve as input. Our method adheres to these data, while producing smooth transitions at branchings and closed, rounded ends by means of convolution surfaces. We discuss the filter design with respect to irritating bulges, unwanted blending and the correct visualization of the vessel diameter. Similar to related work our method is based on the assumption of a circular cross-section of vasculature. In contrast to other authors we employ implicit surfaces to achieve high quality visualization. The method has been applied to a large variety of anatomic trees and produces good results. The time to construct a geometric model is reduced by means of different bounding volumes and careful choice of parameters for polygonization. | false | false | [
"Steffen Oeltze",
"Bernhard Preim"
] | [] | [] | [] |
EuroVis | 2,004 | Visualization of Cardio-CT Data on Standard PC Hardware | 10.2312/VisSym/VisSym04/243-248 | In the last years, texture based volume rendering on the PC platform has proven very successful. Many methods that could formerly only be done with software renderers can now be done completely by the graphics hardware. In this paper we present first results of our ongoing work that deals with the visualization of time dependent CT data of the human heart. We compare the drawbacks and benefits of 3D and 2D texture based methods. We also show that a high quality shaded rendering can considerably improve the visual quality. Then we present our results in the area of classification methods, especially using two-dimensional classification. Finally we demonstrate that it is possible to visualize a beating heart using moderately sized time dependent Cardio-CT data. | false | false | [
"Michael Bauer 0002"
] | [] | [] | [] |
EuroVis | 2,004 | Visualizing Organisms with Hydraulic Body Parts: A Case Study in Integrating Simulation and Visualization Models | 10.2312/VisSym/VisSym04/097-102 | The physical structure of organisms can be modelled as a set of coupled hydraulic entities. The hydropneumatic biosimulation is a methodology that is able to simulate the behavior (like movements) of such organisms on the physical level in a biological correct way. Hydropneumatic simulation heavily relies on visualisation: the simulation model is visually constructed and the simulation results are presented visually to the user. This case study presents an approach, how a visualisation of the results of a hydropneumatic biosimulation can be obtained by integrating the biological simulation model with a Computer Graphics geometry model. | false | false | [
"T. Breiner",
"Ralf Dörner",
"Christian Seiler",
"M. Gudo"
] | [] | [] | [] |
EuroVis | 2,004 | Volume Visualization and Visual Queries for Large High-Dimensional Datasets | 10.2312/VisSym/VisSym04/255-260 | We propose a flexible approach for the visualization of large, high-dimensional datasets. The raw, highdimensional data is mapped into an abstract 3D distance space using the FastMap algorithm, which helps, together with other linear preprocessing steps, to make changes to the resulting 3D representation within a few seconds. Thus exploration of such datasets is a less tedious task compared to other techniques. We use volumes with four components to enable the user to brush an attribute selection onto the volume for inspection. We exploit multiple transfer functions for displaying these attributes and also to filter one attribute with values of another. An advantage of this volume sampling approach is that the rendering performance is independent of the dataset size. The drawback of limited resolution can be overcome by providing a linked detail view for a freely selectable portion of space. Examples of the inspection and filtering possibilities using a silvicultural dataset illustrate the strengths of our approach. | false | false | [
"Guido Reina",
"Thomas Ertl"
] | [] | [] | [] |
CHI | 2,004 | A social proxy for distributed tasks: design and evaluation of a working prototype | 10.1145/985692.985763 | This paper describes an approach to managing tasks and processes that are distributed across a large number of people. The basic idea is to use a social visualization called a task proxy to create a shared awareness amongst the participants in a task or process. The process awareness provided by the task proxy enables its users to monitor the task state, the states of participants, and to communicate with those in particular states. We describe the concept, a first prototype, its evaluation, and discuss future directions. | false | false | [
"Thomas Erickson",
"Wei Huang",
"Catalina Danis",
"Wendy A. Kellogg"
] | [] | [] | [] |
CHI | 2,004 | Connecting time-oriented data and information to a coherent interactive visualization | 10.1145/985692.985706 | In modern intensive care units (ICUs), the medical staff has to monitor a huge amount of high-dimensional and time-oriented data, which needs to be visualized user- and task-specifically to ease diagnosis and treatment planning. Available visual representations, like diagrams or charts neglect the implicit information as well as a-priory or associated knowledge about the data and its meaning (for example, 38.5°C (101.3°F) is moderate fever and 41°C (105.8°F) is critical fever). Another challenge is to provide appropriate interaction techniques to explore and navigate the data and its temporal dimensions. In this context one major challenge is to connect time-oriented data and information to a coherent interactive visualization. In this paper we present different interactive visualization techniques which enable the users to reveal the data at several levels of detail and abstraction, ranging from a broad overview to the fine structure. We will also introduce a time visualization and navigation technique that connects overview+detail, pan+zoom, and focus+context features to one powerful time-browser. | false | false | [
"Ragnar Bade",
"Stefan Schlechtweg",
"Silvia Miksch"
] | [] | [] | [] |
CHI | 2,004 | Feeling bumps and holes without a haptic interface: the perception of pseudo-haptic textures | 10.1145/985692.985723 | We present a new interaction technique to simulate textures in desktop applications without a haptic interface. The proposed technique consists in modifying the motion of the cursor on the computer screen - i.e. the Control/Display ratio. Assuming that the image displayed on the screen corresponds to a top view of the texture, an acceleration (or deceleration) of the cursor indicates a negative (or positive) slope of the texture. Experimental evaluations showed that participants could successfully identify macroscopic textures such as bumps and holes, by simply using the variations of the motion of the cursor. Furthermore, the participants were able to draw the different profiles of bumps and holes which were simulated, correctly. These results suggest that our technique enabled the participants to successfully conjure a mental image of the topography of the macroscopic textures. Applications for this technique are: the feeling of images (pictures, drawings) or GUI components (windows' edges, buttons), the improvement of navigation, or the visualization of scientific data. | false | false | [
"Anatole Lécuyer",
"Jean-Marie Burkhardt",
"Laurent Étienne"
] | [] | [] | [] |
CHI | 2,004 | Studying cooperation and conflict between authors with history flow visualizations | 10.1145/985692.985765 | The Internet has fostered an unconventional and powerful style of collaboration: "wiki" web sites, where every visitor has the power to become an editor. In this paper we investigate the dynamics of Wikipedia, a prominent, thriving wiki. We make three contributions. First, we introduce a new exploratory data analysis tool, the history flow visualization, which is effective in revealing patterns within the wiki context and which we believe will be useful in other collaborative situations as well. Second, we discuss several collaboration patterns highlighted by this visualization tool and corroborate them with statistical analysis. Third, we discuss the implications of these patterns for the design and governance of online collaborative social spaces. We focus on the relevance of authorship, the value of community surveillance in ameliorating antisocial behavior, and how authors with competing perspectives negotiate their differences. | false | false | [
"Fernanda B. Viégas",
"Martin Wattenberg",
"Kushal Dave"
] | [] | [] | [] |
Vis | 2,003 | 3D IBFV: hardware-accelerated 3D flow visualization | 10.1109/VISUAL.2003.1250377 | We present a hardware-accelerated method for visualizing 3D flow fields. The method is based on insertion, advection, and decay of dye. To this aim, we extend the texture-based IBFV technique presented by van Wijk (2001) for 2D flow visualization in two main directions. First, we decompose the 3D flow visualization problem in a series of 2D instances of the mentioned IBFV technique. This makes our method benefit from the hardware acceleration the original IBFV technique introduced. Secondly, we extend the concept of advected gray value (or color) noise by introducing opacity (or matter) noise. This allows us to produce sparse 3D noise pattern advections, thus address the occlusion problem inherent to 3D flow visualization. Overall, the presented method delivers interactively animated 3D flow, uses only standard OpenGL 1.1 calls and 2D textures, and is simple to understand and implement. | false | false | [
"Alexandru C. Telea",
"Jarke J. van Wijk"
] | [] | [] | [] |
Vis | 2,003 | A constraint-based technique for haptic volume exploration | 10.1109/VISUAL.2003.1250381 | We present a haptic rendering technique that uses directional constraints to facilitate enhanced exploration modes for volumetric datasets. The algorithm restricts user motion in certain directions by incrementally moving a proxy point along the axes of a local reference frame. Reaction forces are generated by a spring coupler between the proxy and the data probe, which can be tuned to the capabilities of the haptic interface. Secondary haptic effects including field forces, friction, and texture can be easily incorporated to convey information about additional characteristics of the data. We illustrate the technique with two examples: displaying fiber orientation in heart muscle layers and exploring diffusion tensor fiber tracts in brain white matter tissue. Initial evaluation of the approach indicates that haptic constraints provide an intuitive means or displaying directional information in volume data. | false | false | [
"Milan Ikits",
"J. Dean Brederson",
"Charles D. Hansen",
"Christopher R. Johnson 0001"
] | [] | [] | [] |
Vis | 2,003 | A framework for sample-based rendering with O-buffers | 10.1109/VISUAL.2003.1250405 | We present an innovative modeling and rendering primitive, called the O-buffer, for sample-based graphics, such as images, volumes and points. The 2D or 3D O-buffer is in essence a conventional image or a volume, respectively, except that samples are not restricted to a regular grid. A sample position in the O-buffer is recorded as an offset to the nearest grid point of a regular base grid (hence the name O-buffer). The offset is typically quantized for compact representation and efficient rendering. The O-buffer emancipates pixels and voxels from the regular grids and can greatly improve the modeling power of images and volumes. It is a semi-regular structure which lends itself to efficient construction and rendering. Image quality can be improved by storing more spatial information with samples and by avoiding multiple resamplings and delaying reconstruction to the final rendering stage. Using O-buffers, more accurate multi-resolution representations can be developed for images and volumes. It can also be exploited to represent and render unstructured primitives, such as points, particles, curvilinear or irregular volumes. The O-buffer is therefore a uniform representation for a variety of graphics primitives and supports mixing them in the same scene. We demonstrate the effectiveness of the O-buffer with hierarchical O-buffers, layered depth O-buffers, and hybrid volume rendering with O-buffers. | false | false | [
"Huamin Qu",
"Arie E. Kaufman",
"Ran Shao",
"Ankush Kumar"
] | [] | [] | [] |
Vis | 2,003 | A frequency-sensitive point hierarchy for images and volumes | 10.1109/VISUAL.2003.1250403 | This paper introduces a method for converting an image or volume sampled on a regular grid into a space-efficient irregular point hierarchy. The conversion process retains the original frequency characteristics of the dataset by matching the spatial distribution of sample points with the required frequency. To achieve good blending, the spherical points commonly used in volume rendering are generalized to ellipsoidal point primitives. A family of multiresolution, oriented Gabor wavelets provide the frequency-space analysis of the dataset. The outcome of this frequency analysis is the reduced set of points, in which the sampling rate is decreased in originally oversampled areas. During rendering, the traversal of the hierarchy can be controlled by any suitable error metric or quality criteria. The local level of refinement is also sensitive to the transfer function. Areas with density ranges mapped to high transfer function variability are rendered at higher point resolution than others. Our decomposition is flexible and can be used for iso-surface rendering, alpha compositing and X-ray rendering of volumes. We demonstrate our hierarchy with an interactive splatting volume renderer, in which the traversal of the point hierarchy for rendering is modulated by a user-specified frame rate. | false | false | [
"Tomihisa Welsh",
"Klaus Mueller 0001"
] | [] | [] | [] |
Vis | 2,003 | A multi-resolution data structure for two-dimensional Morse-Smale functions | 10.1109/VISUAL.2003.1250365 | We combine topological and geometric methods to construct a multi-resolution data structure for functions over two-dimensional domains. Starting with the Morse-Smale complex, we construct a topological hierarchy by progressively canceling critical points in pairs. Concurrently, we create a geometric hierarchy by adapting the geometry to the changes in topology. The data structure supports mesh traversal operations similarly to traditional multi-resolution representations. | false | false | [
"Peer-Timo Bremer",
"Herbert Edelsbrunner",
"Bernd Hamann",
"Valerio Pascucci"
] | [] | [] | [] |
Vis | 2,003 | A novel interface for higher-dimensional classification of volume data | 10.1109/VISUAL.2003.1250413 | In the traditional volume visualization paradigm, the user specifies a transfer function that assigns each scalar value to a color and opacity by defining an opacity and a color map function. The transfer function has two limitations. First, the user must define curves based on histogram and value rather than seeing and working with the volume itself. Second, the transfer function is inflexible in classifying regions of interest, where values at a voxel such as intensity and gradient are used to differentiate material, not talking into account additional properties such as texture and position. We describe an intuitive user interface for specifying the classification functions that consists of the users painting directly on sample slices of the volume. These painted regions are used to automatically define high-dimensional classification functions that can be implemented in hardware for interactive rendering. The classification of the volume is iteratively improved as the user paints samples, allowing intuitive and efficient viewing of materials of interest. | false | false | [
"Fan-Yin Tzeng",
"Eric B. Lum",
"Kwan-Liu Ma"
] | [] | [] | [] |
Vis | 2,003 | A texture-based framework for spacetime-coherent visualization of time-dependent vector fields | 10.1109/VISUAL.2003.1250361 | We propose unsteady flow advection-convolution (UFAC) as a novel visualization approach for unsteady flows. It performs time evolution governed by pathlines, but builds spatial correlation according to instantaneous streamlines whose spatial extent is controlled by the flow unsteadiness. UFAC is derived from a generic framework that provides spacetime-coherent dense representations of time dependent-vector fields by a two-step process: 1) construction of continuous trajectories in spacetime for temporal coherence; and 2) convolution along another set of paths through the above spacetime for spatially correlated patterns. Within the framework, known visualization techniques-such as Lagrangian-Eulerian advection, image-based flow visualization, unsteady flow LIC, and dynamic LIC-can be reproduced, often with better image quality, higher performance, or increased flexibility of the visualization style. Finally, we present a texture-based discretization of the framework and its interactive implementation on graphics hardware, which allows the user to gradually balance visualization speed against quality. | false | false | [
"Daniel Weiskopf",
"Gordon Erlebacher",
"Thomas Ertl"
] | [] | [] | [] |
Vis | 2,003 | A visual exploration process for the analysis of Internet routing data | 10.1109/VISUAL.2003.1250415 | The Internet pervades many aspects of our lives and is becoming indispensable to critical functions in areas such as commerce, government, production and general information dissemination. To maintain the stability and efficiency of the Internet, every effort must be made to protect it against various forms of attacks, malicious users, and errors. A key component in the Internet security effort is the routine examination of Internet routing data, which unfortunately can be too large and complicated to browse directly. We have developed an interactive visualization process which proves to be very effective for the analysis of Internet routing data. In this application paper, we show how each step in the visualization process helps direct the analysis and glean insights from the data. These insights include the discovery of patterns, detection of faults and abnormal events, understanding of event correlations, formation of causation hypotheses, and classification of anomalies. We also discuss lessons learned in our visual analysis study. | false | false | [
"Soon Tee Teoh",
"Kwan-Liu Ma",
"Shyhtsun Felix Wu"
] | [] | [] | [] |
Vis | 2,003 | Accelerating large data analysis by exploiting regularities | 10.1109/VISUAL.2003.1250420 | We present techniques for discovering and exploiting regularity in large curvilinear data sets. The data can be based on a single mesh or a mesh composed of multiple submeshes (also known as zones). Multi-zone data are typical in Computational Fluid Dynamics (CFD) simulations. Regularities include axis-aligned rectilinear and cylindrical meshes as well as cases where one zone is equivalent to a rigid body transformation of another. Our algorithms can also discover rigid-body motion of meshes in time-series data. Next, we describe a data model where we can utilize the results from the discovery process in order to accelerate large data visualizations. Where possible, we replace general curvilinear zones with rectilinear or cylindrical zones. In rigid-body motion cases, we replace a time-series of meshes with a transformed mesh object where a reference mesh is dynamically transformed based on a given time value in order to satisfy geometry requests, on demand. The data model enables us to make these substitutions and dynamic transformations transparently with respect to the visualization algorithms. We present results with large data sets where we combine our mesh replacement and transformation techniques with out-of-core paging in order to achieve analysis speedups ranging from 1.5 to 2. | false | false | [
"David Ellsworth",
"Patrick J. Moran"
] | [] | [] | [] |
Vis | 2,003 | Acceleration techniques for GPU-based volume rendering | 10.1109/VISUAL.2003.1250384 | Nowadays, direct volume rendering via 3D textures has positioned itself as an efficient tool for the display and visual analysis of volumetric scalar fields. It is commonly accepted, that for reasonably sized data sets appropriate quality at interactive rates can be achieved by means of this technique. However, despite these benefits one important issue has received little attention throughout the ongoing discussion of texture based volume rendering: the integration of acceleration techniques to reduce per-fragment operations. In this paper, we address the integration of early ray termination and empty-space skipping into texture based volume rendering on graphical processing units (GPU). Therefore, we describe volume ray-casting on programmable graphics hardware as an alternative to object-order approaches. We exploit the early z-test to terminate fragment processing once sufficient opacity has been accumulated, and to skip empty space along the rays of sight. We demonstrate performance gains up to a factor of 3 for typical renditions of volumetric data sets on the ATI 9700 graphics card. | false | false | [
"Jens H. Krüger",
"Rüdiger Westermann"
] | [
"TT"
] | [] | [] |
Vis | 2,003 | Adaptive design of a global opacity transfer function for direct volume rendering of ultrasound data | 10.1109/VISUAL.2003.1250411 | While there are a couple of transfer function design approaches for CT and MRI (magnetic resonance imaging) data, direct volume rendering of ultrasound data still relies on manual adjustment of an inflexible piecewise linear opacity transfer function (OTF) on a trial-and-error basis. The main challenge of automatically designing an OTF for visualization of sonographic data is the low signal-to-noise ratio in combination with real time data acquisition at frame rates up to 25 volumes per second. In this paper, we present an efficient solution of this task. Our approach is based on the evaluation of tube cores, i.e., collections of voxels gathered by traversing the volume in rendering directions. We use information about the probable position of an interface between tissues of different echogenicity to adaptively design an OTF in a multiplicative way. We show the appropriateness of our approach by examples, deliberately on data sets of moderate quality arising frequently in clinical settings. | false | false | [
"Dieter Hönigmann",
"Johannes Ruisz",
"Christoph Haider"
] | [] | [] | [] |
Vis | 2,003 | Advanced curved planar reformation: flattening of vascular structures | 10.1109/VISUAL.2003.1250353 | Traditional volume visualization techniques may provide incomplete clinical information needed for applications in medical visualization. In the area of vascular visualization important features such as the lumen of a diseased vessel segment may not be visible. Curved planar reformation (CPR) has proven to be an acceptable practical solution. Existing CPR techniques, however, still have diagnostically relevant limitations. In this paper, we introduce two advances methods for efficient vessel visualization, based on the concept of CPR. Both methods benefit from relaxation of spatial coherence in favor of improved feature perception. We present a new technique to visualize the interior of a vessel in a single image. A vessel is resampled along a spiral around its central axis. The helical spiral depicts the vessel volume. Furthermore, a method to display an entire vascular tree without mutually occluding vessels is presented. Minimal rotations at the bifurcations avoid occlusions. For each viewing direction the entire vessel structure is visible. | false | false | [
"Armin Kanitsar",
"Rainer Wegenkittl",
"Dominik Fleischmann",
"M. Eduard Gröller"
] | [] | [] | [] |
Vis | 2,003 | Appearance-preserving view-dependent visualization | 10.1109/VISUAL.2003.1250409 | In this paper a new quadric-based view-dependent simplification scheme is presented. The scheme provides a method to connect mesh simplification controlled by a quadric error metric with a level-of-detail hierarchy that is accessed continuously and efficiently based on current view parameters. A variety of methods for determining the screen-space metric for the view calculation are implemented and evaluated, including an appearance-preserving method that has both geometry- and texture-preserving aspects. Results are presented and compared for a variety of models. | false | false | [
"Justin Jang",
"William Ribarsky",
"Chris Shaw 0002",
"Peter Wonka"
] | [] | [] | [] |
Vis | 2,003 | Chameleon: an interactive texture-based rendering framework for visualizing three-dimensional vector fields | 10.1109/VISUAL.2003.1250378 | In this paper we present an interactive texture-based technique for visualizing three-dimensional vector fields. The goal of the algorithm is to provide a general volume rendering framework allowing the user to compute three-dimensional flow textures interactively, and to modify the appearance of the visualization on the fly. To achieve our goal, we decouple the visualization pipeline into two disjoint stages. First, streamlines are generated from the 3D vector data. Various geometric properties of the streamlines are extracted and converted into a volumetric form using a hardware-assisted slice sweeping algorithm. In the second phase of the algorithm, the attributes stored in the volume are used as texture coordinates to look up an appearance texture to generate both informative and aesthetic representations of the underlying vector field. Users can change the input textures and instantaneously visualize the rendering results. With our algorithm, visualizations with enhanced structural perception using various visual cues can be rendered in real time. A myriad of existing geometry-based and texture-based visualization techniques can also be emulated. | false | false | [
"Guo-Shi Li",
"Udeepta Bordoloi",
"Han-Wei Shen"
] | [] | [] | [] |
Vis | 2,003 | Clifford convolution and pattern matching on vector fields | 10.1109/VISUAL.2003.1250372 | The goal of this paper is to define a convolution operation which transfers image processing and pattern matching to vector fields from flow visualization. For this, a multiplication of vectors is necessary. Clifford algebra provides such a multiplication of vectors. We define a Clifford convolution on vector fields with uniform grids. The Clifford convolution works with multivector filter masks. Scalar and vector masks can be easily converted to multivector fields. So, filter masks from image processing on scalar fields can be applied as well as vector and scalar masks. Furthermore, a method for pattern matching with Clifford convolution on vector fields is described. The method is independent of the direction of the structures. This provides an automatic approach to feature detection. The features can be visualized using any known method like glyphs, isosurfaces or streamlines. The features are defined by filter masks instead of analytical properties and thus the approach is more intuitive. | false | false | [
"Julia Ebling",
"Gerik Scheuermann"
] | [] | [] | [] |
Vis | 2,003 | Compression domain volume rendering | 10.1109/VISUAL.2003.1250385 | A survey of graphics developers on the issue of texture mapping hardware for volume rendering would most likely find that the vast majority of them view limited texture memory as one of the most serious drawbacks of an otherwise fine technology. In this paper, we propose a compression scheme for static and time-varying volumetric data sets based on vector quantization that allows us to circumvent this limitation. We describe a hierarchical quantization scheme that is based on a multiresolution covariance analysis of the original field. This allows for the efficient encoding of large-scale data sets, yet providing a mechanism to exploit temporal coherence in non-stationary fields. We show, that decoding and rendering the compressed data stream can be done on the graphics chip using programmable hardware. In this way, data transfer between the CPU and the graphics processing unit (GPU) can be minimized thus enabling flexible and memory efficient real-time rendering options. We demonstrate the effectiveness of our approach by demonstrating interactive renditions of Gigabyte data sets at reasonable fidelity on commodity graphics hardware. | false | false | [
"Jens Schneider 0002",
"Rüdiger Westermann"
] | [] | [] | [] |
Vis | 2,003 | Conveying shape and features with image-based relighting | 10.1109/VISUAL.2003.1250392 | Hand-crafted illustrations are often more effective than photographs for conveying the shape and important features of an object, but they require expertise and time to produce. We describe an image compositing system and user interface that allow an artist to quickly and easily create technical illustrations from a set of photographs of an object taken from the same point of view under variable lighting conditions. Our system uses a novel compositing process in which images are combined using spatially-varying light mattes, enabling the final lighting in each area of the composite to be manipulated independently. We describe an interface that provides for the painting of local lighting effects (e.g. shadows, highlights, and tangential lighting to reveal texture) directly onto the composite. We survey some of the techniques used in illustration and lighting design to convey the shape and features of objects and describe how our system can be used to apply these techniques. | false | false | [
"David Akers",
"Frank Losasso",
"Jeff Klingner",
"Maneesh Agrawala",
"John Rick",
"Pat Hanrahan"
] | [] | [] | [] |
Vis | 2,003 | Counting cases in marching cubes: toward a generic algorithm for producing substitopes | 10.1109/VISUAL.2003.1250354 | We describe how to count the cases that arise in a family of visualization techniques, including marching cubes, sweeping simplices, contour meshing, interval volumes, and separating surfaces. Counting the cases is the first step toward developing a generic visualization algorithm to produce substitopes (geometric substitution of polytopes). We demonstrate the method using a software system ("GAP") for computational group theory. The case-counts are organized into a table that provides taxonomy of members of the family; numbers in the table are derived from actual lists of cases, which are computed by our methods. The calculation confirms previously reported case-counts for large dimensions that are too large to check by hand, and predicts the number of cases that will arise in algorithms that have not yet been invented. | false | false | [
"David C. Banks",
"Stephen A. Linton"
] | [
"BP"
] | [] | [] |
Vis | 2,003 | Curvature-based transfer functions for direct volume rendering: methods and applications | 10.1109/VISUAL.2003.1250414 | Direct volume rendering of scalar fields uses a transfer function to map locally measured data properties to opacities and colors. The domain of the transfer function is typically the one-dimensional space of scalar data values. This paper advances the use of curvature information in multi-dimensional transfer functions, with a methodology for computing high-quality curvature measurements. The proposed methodology combines an implicit formulation of curvature with convolution-based reconstruction of the field. We give concrete guidelines for implementing the methodology, and illustrate the importance of choosing accurate filters for computing derivatives with convolution. Curvature-based transfer functions are shown to extend the expressivity and utility of volume rendering through contributions in three different application areas: nonphotorealistic volume rendering, surface smoothing via anisotropic diffusion, and visualization of isosurface uncertainty. | false | false | [
"Gordon L. Kindlmann",
"Ross T. Whitaker",
"Tolga Tasdizen",
"Torsten Möller"
] | [] | [] | [] |
Vis | 2,003 | Do I really see a bone? | 10.1109/VISUAL.2003.1250429 | Raw data from scanners and simulations has insight embedded within it. However, there is a need to explicitly glean the insight from the data or a version of it. Visualization algorithms and methods are designed just to do that. What insight is to be gleaned depends on the data, its use, and the medium of display. Thus, visualization embodies all tasks that increase information content and understanding when presented to the users. | false | false | [
"Raghu Machiraju",
"Christopher R. Johnson 0001",
"Terry S. Yoo",
"Roger Crawfis",
"David S. Ebert",
"Don Stredney"
] | [] | [] | [] |
Vis | 2,003 | Effectively visualizing multi-valued flow data using color and texture | 10.1109/VISUAL.2003.1250362 | In this paper we offer several new insights and techniques for effectively using color and texture to simultaneously convey information about multiple 2D scalar and vector distributions, in a way that facilitates allowing each distribution to be understood both individually and in the context of one or more of the other distributions. Specifically, we introduce the concepts of: color weaving for simultaneously representing information about multiple co-located color encoded distributions; and texture stitching for achieving more spatially accurate multi-frequency line integral convolution representations of combined scalar and vector distributions. The target application for our research is the definition, detection and visualization of regions of interest in a turbulent boundary layer flow at moderate Reynolds number. In this work, we examine and analyze streamwise-spanwise planes of three-component velocity vectors with the goal of identifying and characterizing spatially organized packets of hairpin vortices. | false | false | [
"Timothy Urness",
"Victoria Interrante",
"Ivan Marusic",
"Ellen Longmire",
"Bharathram Ganapathisubramani"
] | [] | [] | [] |
Vis | 2,003 | Empty space skipping and occlusion clipping for texture-based volume rendering | 10.1109/VISUAL.2003.1250388 | We propose methods to accelerate texture-based volume rendering by skipping invisible voxels. We partition the volume into sub-volumes, each containing voxels with similar properties. Sub-volumes composed of only voxels mapped to empty by the transfer function are skipped. To render the adaptively partitioned sub-volumes in visibility order, we reorganize them into an orthogonal BSP tree. We also present an algorithm that computes incrementally the intersection of the volume with the slicing planes, which avoids the overhead of the intersection and texture coordinates computation introduced by the partitioning. Rendering with empty space skipping is 2 to 5 times faster than without it. To skip occluded voxels, we introduce the concept of orthogonal opacity map, that simplifies the transformation between the volume coordinates and the opacity map coordinates, which is intensively used for occlusion detection. The map is updated efficiently by the GPU. The sub-volumes are then culled and clipped against the opacity map. We also present a method that adaptively adjusts the optimal number of the opacity map updates. With occlusion clipping, about 60% of non-empty voxels can be skipped and an additional 80% speedup on average is gained for iso-surface-like rendering. | false | false | [
"Wei Li 0004",
"Klaus Mueller 0001",
"Arie E. Kaufman"
] | [] | [] | [] |
Vis | 2,003 | Exploring curved anatomic structures with surface sections | 10.1109/VISUAL.2003.1250351 | The extraction of planar sections from volume images is the most commonly used technique for inspecting and visualizing anatomic structures. We propose to generalize the concept of planar section to the extraction of curved cross-sections (free form surfaces). Compared with planar slices, curved cross-sections may easily follow the trajectory of tubular structures and organs such as the aorta or the colon. They may be extracted from a 3D volume, displayed as a 3D view and possibly flattened. Flattening of curved cross-sections allows to inspect spatially complex relationship between anatomic structures and their neighborhood. They also allow to carry out measurements along a specific orientation. For the purpose of facilitating the interactive specification of free form surfaces, users may navigate in real time within the body and select the slices on which the surface control points will be positioned. Immediate feedback is provided by displaying boundary curves as cylindrical markers within a 3D view composed of anatomic organs, planar slices and possibly free form surface sections. Extraction of curved surface sections is an additional service that is available online as a Java applet (http://visiblehuman.epfl.ch). It may be used as an advanced tool for exploring and teaching anatomy. | false | false | [
"Laurent Saroul",
"Sebastian Gerlach",
"Roger D. Hersch"
] | [] | [] | [] |
Vis | 2,003 | Extraction of topologically simple isosurfaces from volume datasets | 10.1109/VISUAL.2003.1250356 | There are numerous algorithms in graphics and visualization whose performance is known to decay as the topological complexity of the input increases. On the other hand, the standard pipeline for 3D geometry acquisition often produces 3D models that are topologically more complex than their real forms. We present a simple and efficient algorithm that allows us to simplify the topology of an isosurface by alternating the values of some number of voxels. Its utility and performance are demonstrated on several examples, including signed distance functions from polygonal models and CT scans. | false | false | [
"Andrzej Szymczak",
"James Vanderhyde"
] | [] | [] | [] |
Vis | 2,003 | Fairing scalar fields by variational modeling of contours | 10.1109/VISUAL.2003.1250398 | Volume rendering and isosurface extraction from three-dimensional scalar fields are mostly based on piecewise trilinear representations. In regions of high geometric complexity such visualization methods often exhibit artifacts, due to trilinear interpolation. In this work, we present an iterative fairing method for scalar fields interpolating function values associated with grid points while smoothing the contours inside the grid cells based on variational principles. We present a local fairing method providing a piecewise bicubic representation of two-dimensional scalar fields. Our algorithm generalizes to the trivariate case and can be used to increase the resolution of data sets either locally or globally, reducing interpolation artifacts. In contrast to filtering methods, our algorithm does not reduce geometric detail supported by the data. | false | false | [
"Martin Hering-Bertram"
] | [] | [] | [] |
Vis | 2,003 | Fast volume segmentation with simultaneous visualization using programmable graphics hardware | 10.1109/VISUAL.2003.1250369 | Segmentation of structures from measured volume data, such as anatomy in medical imaging, is a challenging data-dependent task. In this paper, we present a segmentation method that leverages the parallel processing capabilities of modern programmable graphics hardware in order to run significantly faster than previous methods. In addition, collocating the algorithm computation with the visualization on the graphics hardware circumvents the need to transfer data across the system bus, allowing for faster visualization and interaction. This algorithm is unique in that it utilizes sophisticated graphics hardware functionality (i.e., floating point precision, render to texture, computational masking, and fragment programs) to enable fast segmentation and interactive visualization. | false | false | [
"Anthony J. Sherbondy",
"Michael Houston",
"Sandy Napel"
] | [] | [] | [] |
Vis | 2,003 | Feature-sensitive subdivision and isosurface reconstruction | 10.1109/VISUAL.2003.1250360 | We present improved subdivision and isosurface reconstruction algorithms for polygonizing implicit surfaces and performing accurate geometric operations. Our improved reconstruction algorithm uses directed distance fields (Kobbelt et al., 2001) to detect multiple intersections along an edge, separates them into components and reconstructs an isosurface locally within each components using the dual contouring algorithm (Ju et al., 2002). It can reconstruct thin features without creating handles and results in improved surface extraction from volumetric data. Our subdivision algorithm takes into account sharp features that arise from intersecting surfaces or Boolean operations and generates an adaptive grid such that each voxel has at most one sharp feature. The subdivision algorithm is combined with our improved reconstruction algorithm to compute accurate polygonization of Boolean combinations or offsets of complex primitives that faithfully reconstruct the sharp features. We have applied these algorithms to polygonize complex CAD models designed using thousands of Boolean operations on curved primitives. | false | false | [
"Gokul Varadhan",
"Shankar Krishnan",
"Young J. Kim",
"Dinesh Manocha"
] | [] | [] | [] |
Vis | 2,003 | Feature-space analysis of unstructured meshes | 10.1109/VISUAL.2003.1250371 | Unstructured meshes are often used in simulations and imaging applications. They provide advanced flexibility in modeling abilities but are more difficult to manipulate and analyze than regular data. This work provides a novel approach for the analysis of unstructured meshes using feature-space clustering and feature-detection. Analyzing and revealing underlying structures in data involve operators on both spatial and functional domains. Slicing concentrates more on the spatial domain, while iso-surfacing or volume rendering concentrate more on the functional domain. Nevertheless, many times it is the combination of the two domains which provides real insight on the structure of the data. In this work, a combined feature-space is defined on top of unstructured meshes in order to search for structure in the data. A point in feature-space includes the spatial coordinates of the point in the mesh domain and all chosen attributes defined on the mesh. A distance measures between points in feature-space is defined enabling the utilization of clustering using the mean shift procedure (previously used for images) on unstructured meshes. Feature space analysis is shown to be useful for feature-extraction, for data exploration and partitioning. | false | false | [
"Ariel Shamir"
] | [] | [] | [] |
Vis | 2,003 | Gaussian transfer functions for multi-field volume visualization | 10.1109/VISUAL.2003.1250412 | Volume rendering is a flexible technique for visualizing dense 3D volumetric datasets. A central element of volume rendering is the conversion between data values and observable quantities such as color and opacity. This process is usually realized through the use of transfer functions that are precomputed and stored in lookup tables. For multidimensional transfer functions applied to multivariate data, these lookup tables become prohibitively large. We propose the direct evaluation of a particular type of transfer functions based on a sum of Gaussians. Because of their simple form (in terms of number of parameters), these functions and their analytic integrals along line segments can be evaluated efficiently on current graphics hardware, obviating the need for precomputed lookup tables. We have adopted these transfer functions because they are well suited for classification based on a unique combination of multiple data values that localize features in the transfer function domain. We apply this technique to the visualization of several multivariate datasets (CT, cryosection) that are difficult to classify and render accurately at interactive rates using traditional approaches. | false | false | [
"Joe Michael Kniss",
"Simon Premoze",
"Milan Ikits",
"Aaron E. Lefohn",
"Charles D. Hansen",
"Emil Praun"
] | [] | [] | [] |
Vis | 2,003 | Hardware-based nonlinear filtering and segmentation using high-level shading languages | 10.1109/VISUAL.2003.1250387 | Non-linear filtering is an important task for volume analysis. This paper presents hardware-based implementations of various non-linear filters for volume smoothing with edge preservation. The Cg high-level shading language is used in combination with latest PC consumer graphics hardware. Filtering is divided into pervertex and per-fragment stages. In both stages we propose techniques to increase the filtering performance. The vertex program pre-computes texture coordinates in order to address all contributing input samples of the operator mask. Thus additional computations are avoided in the fragment program. The presented fragment programs preserve cache coherence, exploit 4D vector arithmetic, and internal fixed point arithmetic to increase performance. We show the applicability of non-linear filters as part of a GPU-based segmentation pipeline. The resulting binary mask is compressed and decompressed in the graphics memory on-the-fly. | false | false | [
"Ivan Viola",
"Armin Kanitsar",
"M. Eduard Gröller"
] | [] | [] | [] |
Vis | 2,003 | Hardware-based ray casting for tetrahedral meshes | 10.1109/VISUAL.2003.1250390 | We present the first implementation of a volume ray casting algorithm for tetrahedral meshes running on off-the-shelf programmable graphics hardware. Our implementation avoids the memory transfer bottleneck of the graphics bus since the complete mesh data is stored in the local memory of the graphics adapter and all computations, in particular ray traversal and ray integration, are performed by the graphics processing unit. Analogously to other ray casting algorithms, our algorithm does not require an expensive cell sorting. Provided that the graphics adapter offers enough texture memory, our implementation performs comparable to the fastest published volume rendering algorithms for unstructured meshes. Our approach works with cyclic and/or non-convex meshes and supports early ray termination. Accurate ray integration is guaranteed by applying pre-integrated volume rendering. In order to achieve almost interactive modifications of transfer functions, we propose a new method for computing three-dimensional pre-integration tables. | false | false | [
"Manfred Weiler",
"Martin Kraus",
"Markus Merz",
"Thomas Ertl"
] | [] | [] | [] |
Vis | 2,003 | Heart-muscle fiber reconstruction from diffusion tensor MRI | 10.1109/VISUAL.2003.1250425 | In this paper we use advanced tensor visualization techniques to study 3D diffusion tensor MRI data of a heart. We use scalar and tensor glyph visualization methods to investigate the data and apply a moving least squares (MLS) fiber tracing method to recover and visualize the helical structure and the orientation of the heart muscle fibers. | false | false | [
"Leonid Zhukov",
"Alan H. Barr"
] | [] | [] | [] |
Vis | 2,003 | Hierarchical clustering for unstructured volumetric scalar fields | 10.1109/VISUAL.2003.1250389 | We present a method to represent unstructured scalar fields at multiple levels of detail. Using a parallelizable classification algorithm to build a cluster hierarchy, we generate a multiresolution representation of a given volumetric scalar data set. The method uses principal component analysis (PCA) for cluster generation and a fitting technique based on radial basis functions (RBFs). Once the cluster hierarchy has been generated, we utilize a variety of techniques for extracting different levels of detail. The main strength of this work is its generality. Regardless of grid type, this method can be applied to any discrete scalar field representation, even one given as a "point cloud". | false | false | [
"Christopher S. Co",
"Bjørn Heckel",
"Hans Hagen",
"Bernd Hamann",
"Kenneth I. Joy"
] | [] | [] | [] |
Vis | 2,003 | Hierarchical splatting of scattered data | 10.1109/VISUAL.2003.1250404 | Numerical particle simulations and astronomical observations create huge data sets containing uncorrelated 3D points of varying size. These data sets cannot be visualized interactively by simply rendering millions of colored points for each frame. Therefore, in many visualization applications a scalar density corresponding to the point distribution is resampled on a regular grid for direct volume rendering. However, many fine details are usually lost for voxel resolutions which still allow interactive visualization on standard workstations. Since no surface geometry is associated with our data sets, the recently introduced point-based rendering algorithms cannot be applied as well. In this paper we propose to accelerate the visualization of scattered point data by a hierarchical data structure based on a PCA clustering procedure. By traversing this structure for each frame we can trade-off rendering speed vs. image quality. Our scheme also reduces memory consumption by using quantized relative coordinates and it allows for fast sorting of semi-transparent clusters. We analyze various software and hardware implementations of our renderer and demonstrate that we can now visualize data sets with tens of millions of points interactively with sub-pixel screen space error on current PC graphics hardware employing advanced vertex shader functionality. | false | false | [
"Matthias Hopf",
"Thomas Ertl"
] | [] | [] | [] |
Vis | 2,003 | High dimensional direct rendering of time-varying volumetric data | 10.1109/VISUAL.2003.1250402 | We present an alternative method for viewing time-varying volumetric data. We consider such data as a four-dimensional data field, rather than considering space and time as separate entities. If we treat the data in this manner, we can apply high dimensional slicing and projection techniques to generate an image hyperplane. The user is provided with an intuitive user interface to specify arbitrary hyperplanes in 4D, which can be displayed with standard volume rendering techniques. From the volume specification, we are able to extract arbitrary hyperslices, combine slices together into a hyperprojection volume, or apply a 4D raycasting method to generate the same results. In combination with appropriate integration operators and transfer functions, we are able to extract and present different space-time features to the user. | false | false | [
"Jonathan Woodring",
"Chaoli Wang 0001",
"Han-Wei Shen"
] | [] | [] | [] |
Vis | 2,003 | High-quality two-level volume rendering of segmented data sets on consumer graphics hardware | 10.1109/VISUAL.2003.1250386 | One of the most important goals in volume rendering is to be able to visually separate and selectively enable specific objects of interest contained in a single volumetric data set, which can be approached by using explicit segmentation information. We show how segmented data sets can be rendered interactively on current consumer graphics hardware with high image quality and pixel-resolution filtering of object boundaries. In order to enhance object perception, we employ different levels of object distinction. First, each object can be assigned an individual transfer function, multiple of which can be applied in a single rendering pass. Second, different rendering modes such as direct volume rendering, iso-surfacing, and non-photorealistic techniques can be selected for each object. A minimal number of rendering passes is achieved by processing sets of objects that share the same rendering mode in a single pass. Third, local compositing modes such as alpha blending and MIP can be selected for each object in addition to a single global mode, thus enabling high-quality two-level volume rendering on GPUs. | false | false | [
"Markus Hadwiger",
"Christoph Berger",
"Helwig Hauser"
] | [] | [] | [] |
Vis | 2,003 | Holographic video display of time-series volumetric medical data | 10.1109/VISUAL.2003.1250424 | We describe an animated electro-holographic visualization of brain lesions due to the progression of multiple sclerosis. A research case study is used which documents the expression of visible brain lesions in a series of magnetic resonance imaging (MRI) volumes collected over the interval of one year. Some of the salient information resident within this data is described, and the motivation for using a dynamic spatial display to explore its spatial and temporal characteristics is stated. We provide a brief overview of spatial displays in medical imaging applications, and then describe our experimental visualization pipeline, from the processing of MRI datasets, through model construction, computer graphic rendering, and hologram encoding. The utility, strengths and shortcomings of the electro-holographic visualization are described and future improvements are suggested. | false | false | [
"Wendy Plesniak",
"Michael Halle",
"Steven D. Pieper",
"William M. Wells III",
"Marianna Jakab",
"Dominik S. Meier",
"Stephen A. Benton",
"Charles R. G. Guttmann",
"Ron Kikinis"
] | [] | [] | [] |
Vis | 2,003 | Hybrid segmentation and exploration of the human lungs | 10.1109/VISUAL.2003.1250370 | Segmentation of the tracheo-bronchial tree of the lungs is notoriously difficult. This is due to the fact that the small size of some of the anatomical structures is subject to partial volume effects. Furthermore, the limited intensity contrast between the participating materials (air, blood, and tissue) increases the segmentation of difficulties. In this paper, we propose a hybrid segmentation method which is based on a pipeline of three segmentation stages to extract the lower airways down to the seventh generation of the bronchi. User interaction is limited to the specification of a seed point inside the easily detectable trachea at the upper end of the lower airways. Similarly, the complementary vascular tree of the lungs can be segmented. Furthermore, we modified our virtual endoscopy system to visualize the vascular and airway system of the lungs along with other features, such as lung tumors. | false | false | [
"Dirk Bartz",
"Dirk Mayer",
"Jan Fischer",
"Sebastian Ley",
"Ángel del Río",
"Steffi Thust",
"Claus Peter Heussel",
"Hans-Ulrich Kauczor",
"Wolfgang Straßer"
] | [] | [] | [] |
Vis | 2,003 | HyperLIC | 10.1109/VISUAL.2003.1250379 | We introduce a new method for visualizing symmetric tensor fields. The technique produces images and animations reminiscent of line integral convolution (LIC). The technique is also slightly related to hyperstreamlines in that it is used to visualize tensor fields. However, the similarity ends there. HyperLIC uses a multi-pass approach to show the anisotropic properties in a 2D or 3D tensor field. We demonstrate this technique using data sets from computational fluid dynamics as well as diffusion-tensor MRI. | false | false | [
"Xiaoqiang Zheng",
"Alex T. Pang"
] | [] | [] | [] |
Vis | 2,003 | IEEE Visualization 2003 (IEEE Cat. No.03CH37496) | 10.1109/VISUAL.2003.1250348 | The following topics are dealt with: medical visualization; isosurfaces; implicit surfaces; flow visualization; terrains and view-dependent methods; segmentation and feature analysis; haptics and physical simulation; hardware-assisted volume rendering; volume rendering acceleration; shading and shape perception; volume reconstruction; volumetric techniques; sample-based rendering; mesh simplification; transfer functions; information visualization; scientific and large data visualization; visualization in medicine and biology; and visualization software. | false | false | [
"Greg Turk",
"Jarke J. van Wijk",
"Robert J. Moorhead II"
] | [] | [] | [] |
Vis | 2,003 | Image based flow visualization for curved surfaces | 10.1109/VISUAL.2003.1250363 | A new method for the synthesis of dense, vector-field aligned textures on curved surfaces is presented, called IBFVS. The method is based on image based flow visualization (IBFV). In IBFV two-dimensional animated textures are produced by defining each frame of a flow animation as a blend between a warped version of the previous image and a number of filtered white noise images. We produce flow aligned texture on arbitrary three-dimensional triangular meshes in the same spirit as the original method: texture is generated directly in image space. We show that IBFVS is efficient and effective. High performance (typically fifty frames or more per second) is achieved by exploiting graphics hardware. Also, IBFVS can easily be implemented and a variety of effects can be achieved. Applications are flow visualization and surface rendering. Specifically, we show how to visualize the wind field on the earth and how to render a dirty bronze bunny. | false | false | [
"Jarke J. van Wijk"
] | [] | [] | [] |
Vis | 2,003 | Image space based visualization of unsteady flow on surfaces | 10.1109/VISUAL.2003.1250364 | We present a technique for direct visualization of unsteady flow on surfaces from computational fluid dynamics. The method generates dense representations of time-dependent vector fields with high spatio-temporal correlation using both Lagrangian-Eulerian advection and image based flow visualization as its foundation. While the 3D vector fields are associated with arbitrary triangular surface meshes, the generation and advection of texture properties is confined to image space. Frame rates of up to 20 frames per second are realized by exploiting graphics card hardware. We apply this algorithm to unsteady flow on boundary surfaces of, large, complex meshes from computational fluid dynamics composed of more than 250,000 polygons, dynamic meshes with time-dependent geometry and topology, as well as medical data. | false | false | [
"Robert S. Laramee",
"Bruno Jobard",
"Helwig Hauser"
] | [] | [] | [] |
Vis | 2,003 | Information and scientific visualization: separate but equal or happy together at last | 10.1109/VISUAL.2003.1250428 | Must we continue to define a difference between information and scientific visualization? Scientific visualization evolved first in the late 1980’s while information visualization matured in the mid-1990’s. Scientific visualization is frequently considered to focus on the visual display of spatial data associated with scientific processes such as the bonding of molecules in computational chemistry. Information visualization examines developing visual metaphors for non-inherently spatial data such as the exploration of text-based document databases. This panel examines the effective, productive, and perhaps confusing tension between these subfields of visualization by highlighting the following issues: | false | false | [
"Theresa-Marie Rhyne",
"Melanie Tory",
"Tamara Munzner",
"Matthew O. Ward",
"Christopher R. Johnson 0001",
"David H. Laidlaw"
] | [] | [] | [] |
Vis | 2,003 | Interactive 3D visualization of rigid body systems | 10.1109/VISUAL.2003.1250417 | Simulation of rigid body dynamics has been a field of active research for quite some time. However, the presentation of simulation results has received far less attention so far. We present an interactive and intuitive 3D visualization framework for rigid body simulation data. We introduce various glyphs representing vector attributes such as force and velocity as well as angular attributes including angular velocity and torque. We have integrated our visualization method into an application developed at one of the leading companies in automotive engine design and simulation. We apply our principles to visualization of chain and belt driven timing drives in engines. | false | false | [
"Zoltan Konyha",
"Kresimir Matkovic",
"Helwig Hauser"
] | [] | [] | [] |
Vis | 2,003 | Interactive deformation and visualization of level set surfaces using graphics hardware | 10.1109/VISUAL.2003.1250357 | Deformable isosurfaces, implemented with level-set methods, have demonstrated a great potential in visualization for applications such as segmentation, surface processing, and surface reconstruction. Their usefulness has been limited, however, by their high computational cost and reliance on significant parameter tuning. This paper presents a solution to these challenges by describing graphics processor (GPU) based on algorithms for solving and visualizing level-set solutions at interactive rates. Our efficient GPU-based solution relies on packing the level-set isosurface data into a dynamic, sparse texture format. As the level set moves, this sparse data structure is updated via a novel GPU to CPU message passing scheme. When the level-set solver is integrated with a real-time volume renderer operating on the same packed format, a user can visualize and steer the deformable level-set surface as it evolves. In addition, the resulting isosurface can serve as a region-of-interest specifier for the volume renderer. This paper demonstrates the capabilities of this technology for interactive volume visualization and segmentation. | false | false | [
"Aaron E. Lefohn",
"Joe Michael Kniss",
"Charles D. Hansen",
"Ross T. Whitaker"
] | [] | [] | [] |
Vis | 2,003 | Interactive protein manipulation | 10.1109/VISUAL.2003.1250423 | We describe an interactive visualization and modeling program for the creation of protein structures "from scratch." The input to our program is an amino acid sequence - decoded from a gene - and a sequence of predicted secondary structure types for each amino acid - provided by external structure prediction programs. Our program can be used in the set-up phase of a protein structure prediction process; the structures created with it serve as input for a subsequent global internal energy minimization, or another method of protein structure prediction. Our program supports basic visualization methods for protein structures, interactive manipulation based on inverse kinematics, and visualization guides to aid a user in creating "good" initial structures. | false | false | [
"Oliver Kreylos",
"Nelson L. Max",
"Bernd Hamann",
"Silvia N. Crivelli",
"E. Wes Bethel"
] | [
"BA"
] | [] | [] |
Vis | 2,003 | Interactive view-dependent rendering with conservative occlusion culling in complex environments | 10.1109/VISUAL.2003.1250368 | This paper presents an algorithm combining view-dependent rendering and conservative occlusion culling for interactive display of complex environments. A vertex hierarchy of the entire scene is decomposed into a cluster hierarchy through a novel clustering and partitioning algorithm. The cluster hierarchy is then used for view-frustum and occlusion culling. Using hardware accelerated occlusion queries and frame-to-frame coherence, a potentially visible set of clusters is computed. An active vertex front and face list is computed from the visible clusters and rendered using vertex arrays. The integrated algorithm has been implemented on a Pentium IV PC with a NVIDIA GeForce 4 graphics card and applied in two complex environments composed of millions of triangles. The resulting system can render these environments at interactive rates with little loss in image quality and minimal popping artifacts. | false | false | [
"Sung-Eui Yoon",
"Brian Salomon",
"Dinesh Manocha"
] | [] | [] | [] |
Vis | 2,003 | Interoperability of visualization software and data models is not an achievable goal | 10.1109/VISUAL.2003.1250427 | Author(s): Bethel, E. Wes | Abstract: The scientific visualization community faces a crisis: there exist many individual tools that can be used to perform visualization, but there is little, if any, hope of being able to use tools from different sources as part of a single application. As a result, our community is fractured, and can be characterized as "islands of capability." The purpose of this panel is to probe the issues that prevent such interoperability, and engage in frank discussion about how our community can rectify these maladies. The issues to be discussed include but are not limited to: (1)lack of "standards" for data storage and modelling of N-dimensional scientific data, similar to those used for raster image files; (2)lack of "standard" interfaces for common visualization tools; (3)the visualization needs of the computational science research community, who are the primary consumers of technology from the visualization community; (4)lack of organization within our community to push for definition and adoption of such "standards;" (5)lack of organization within our community to serve as a "broker" and "promoter" for tools that might conform to even the weakest of standards. The panelist lineup represents a diverse cross-section of expertise and opinions about the panel topic. The panelists themselves are in disagreement about the severity of the problem, and potential solutions. The topic of this panel is highly germane to future growth of visualization as a science, and promises to be highly engaging for panelists and audience members alike. | false | false | [
"E. Wes Bethel",
"Greg Abram",
"John Shalf",
"Randy Frank",
"James P. Ahrens",
"Steven G. Parker",
"Nagiza F. Samatova",
"Mark C. Miller"
] | [] | [] | [] |
Vis | 2,003 | Large mesh simplification using processing sequences | 10.1109/VISUAL.2003.1250408 | In this paper we show how out-of-core mesh processing techniques can be adapted to perform their computations based on the new processing sequence paradigm (Isenburg, et al., 2003), using mesh simplification as an example. We believe that this processing concept will also prove useful for other tasks, such a parameterization, remeshing, or smoothing, for which currently only in-core solutions exist. A processing sequence represents a mesh as a particular interleaved ordering of indexed triangles and vertices. This representation allows streaming very large meshes through main memory while maintaining information about the visitation status of edges and vertices. At any time, only a small portion of the mesh is kept in-core, with the bulk of the mesh data residing on disk. Mesh access is restricted to a fixed traversal order, but full connectivity and geometry information is available for the active elements of the traversal. This provides seamless and highly efficient out-of-core access to very large meshes for algorithms that can adapt their computations to this fixed ordering. The two abstractions that are naturally supported by this representation are boundary-based and buffer-based processing. We illustrate both abstractions by adapting two different simplification methods to perform their computation using a prototype of our mesh processing sequence API. Both algorithms benefit from using processing sequences in terms of improved quality, more efficient execution, and smaller memory footprints. | false | false | [
"Martin Isenburg",
"Peter Lindstrom 0001",
"Stefan Gumhold",
"Jack Snoeyink"
] | [] | [] | [] |
Vis | 2,003 | LightKit: a lighting system for effective visualization | 10.1109/VISUAL.2003.1250395 | LightKit is a system for lighting three-dimensional synthetic scenes. LightKit simplifies the task of producing visually pleasing, easily interpretable images for visualization while making it harder to produce results where the scene illumination distracts from the visualization process. LightKit is based on lighting designs developed by artists and photographers and shown in previous studies to enhance shape perception. A key light provides natural overhead illumination of the scene, augmented by fill, head, and back lights. By default, lights are attached to a normalized, subject-centric, camera-relative coordinate frame to ensure consistent lighting independent of camera location or orientation. This system allows all lights to be positioned by specifying just six parameters. The intensity of each light is specified as a ratio to the key light intensity, allowing the scene's brightness to be adjusted using a single parameter. The color of each light is specified by a single normalized color parameter called warmth that is based on color temperature of natural sources. LightKit's default values for light position, intensity, and color are chosen to produce good results for a variety of scenes. LightKit is designed to work with both hardware graphics systems and, potentially, higher quality off-line rendering systems. We provide examples of images created using a LightKit implementation within the VTK visualization toolkit software framework. | false | false | [
"Michael Halle",
"Jeanette C. Meng"
] | [] | [] | [] |
Vis | 2,003 | MC*: star functions for marching cubes | 10.1109/VISUAL.2003.1250355 | We describe a modification of the widely used marching cubes method that leads to the useful property that the resulting isosurfaces are locally single valued functions. This implies that conventional interpolation and approximation methods can be used to locally represent the surface. These representations can be used for computing approximations for local surface properties. We utilize this possibility in order to develop algorithms for locally approximating Gaussian and mean curvature, methods for constrained smoothing of isosurface, and techniques for the parameterization of isosurfaces. | false | false | [
"Gregory M. Nielson"
] | [] | [] | [] |
Vis | 2,003 | Mental registration of 2D and 3D visualizations (an empirical study) | 10.1109/VISUAL.2003.1250396 | 2D and 3D views are used together in many visualization domains, such as medical imaging, flow visualization, oceanographic visualization, and computer aided design (CAD). Combining these views into one display can be done by: (1) orientation icon (i.e., separate windows), (2) in-place methods (e.g., clip and cutting planes), and (3) a new method called ExoVis. How 2D and 3D views are displayed affects ease of mental registration (understanding the spatial relationship between views), an important factor influencing user performance. This paper compares the above methods in terms of their ability to support mental registration. Empirical results show that mental registration is significantly easier with in-place displays than with ExoVis, and significantly easier with ExoVis than with orientation icons. Different mental transformation strategies can explain this result. The results suggest that ExoVis may be a better alternative to orientation icons when in-place displays are not appropriate (e.g., when in-place methods hide data or cut the 3D view into several pieces). | false | false | [
"Melanie Tory"
] | [] | [] | [] |
Vis | 2,003 | Monte Carlo volume rendering | 10.1109/VISUAL.2003.1250406 | In this paper a novel volume-rendering technique based on Monte Carlo integration is presented. As a result of a preprocessing, a point cloud of random samples is generated using a normalized continuous reconstruction of the volume as a probability density function. This point cloud is projected onto the image plane, and to each pixel an intensity value is assigned which is proportional to the number of samples projected onto the corresponding pixel area. In such a way a simulated X-ray image of the volume can be obtained. Theoretically, for a fixed image resolution, there exists an M number of samples such that the average standard deviation of the estimated pixel intensities us under the level of quantization error regardless of the number of voxels. Therefore Monte Carlo Volume Rendering (MCVR) is mainly proposed to efficiently visualize large volume data sets. Furthermore, network applications are also supported, since the trade-off between image quality and interactivity can be adapted to the bandwidth of the client/server connection by using progressive refinement. | false | false | [
"Balázs Csébfalvi",
"László Szirmay-Kalos"
] | [] | [] | [] |
Vis | 2,003 | Out-of-core isosurface extraction of time-varying fields over irregular grids | 10.1109/VISUAL.2003.1250375 | In this paper, we propose a novel out-of-core isosurface extraction technique for large time-varying fields over irregular grids. We employ our meta-cell technique to explore the spatial coherence of the data, and our time tree algorithm to consider the temporal coherence as well. Our one-time preprocessing phase first partitions the dataset into meta-cells that cluster spatially neighboring cells together and are stored in disk. We then build a time tree to index the meta-cells for fast isosurface extraction. The time tree takes advantage of the temporal coherence among the scalar values at different time steps, and uses BBIO trees as secondary structures, which are stored in disk and support I/O-optimal interval searches. The time tree algorithm employs a novel meta-interval collapsing scheme and the buffer technique, to take care of the temporal coherence in an I/O-efficient way. We further make the time tree cache-oblivious, so that searching on it automatically performs optimal number of block transfers between any two consecutive levels of memory hierarchy (such as between cache and main memory and between main memory and disk) simultaneously. At run-time, we perform optimal cache-oblivious searches in the time tree, together with I/O-optimal searches in the BBIO trees, to read the active meta-cells from disk and generate the queried isosurface efficiently. The experiments demonstrate the effectiveness of our new technique. In particular, compared with the query-optimal main-memory algorithm by Cignoni et al. (1997) (extended for time-varying fields) when there is not enough main memory, our technique can speed up the isosurface queries from more than 18 hours to less than 4 minutes. | false | false | [
"Yi-Jen Chiang"
] | [] | [] | [] |
Vis | 2,003 | Piecewise C¹ continuous surface reconstruction of noisy point clouds via local implicit quadric regression | 10.1109/VISUAL.2003.1250359 | This paper addresses the problem of surface reconstruction of highly noisy point clouds. The surfaces to be reconstructed are assumed to be 2-manifolds of piecewise C/sup 1/ continuity, with isolated small irregular regions of high curvature, sophisticated local topology or abrupt burst of noise. At each sample point, a quadric field is locally fitted via a modified moving least squares method. These locally fitted quadric fields are then blended together to produce a pseudo-signed distance field using Shepard's method. We introduce a prioritized front growing scheme in the process of local quadrics fitting. Flatter surface areas tend to grow faster. The already fitted regions will subsequently guide the fitting of those irregular regions in their neighborhood. | false | false | [
"Hui Xie 0001",
"Jianning Wang",
"Jing Hua 0001",
"Hong Qin",
"Arie E. Kaufman"
] | [] | [] | [] |
Vis | 2,003 | Planet-sized batched dynamic adaptive meshes (P-BDAM) | 10.1109/VISUAL.2003.1250366 | We describe an efficient technique for out-of-core management and interactive rendering of planet sized textured terrain surfaces. The technique, called planet-sized batched dynamic adaptive meshes (P-BDAM), extends the BDAM approach by using as basic primitive a general triangulation of points on a displaced triangle. The proposed framework introduces several advances with respect to the state of the art: thanks to a batched host-to-graphics communication model, we outperform current adaptive tessellation solutions in terms of rendering speed; we guarantee overall geometric continuity, exploiting programmable graphics hardware to cope with the accuracy issues introduced by single precision floating points; we exploit a compressed out of core representation and speculative prefetching for hiding disk latency during rendering of out-of-core data; we efficiently construct high quality simplified representations with a novel distributed out of core simplification algorithm working on a standard PC network. | false | false | [
"Paolo Cignoni",
"Fabio Ganovelli",
"Enrico Gobbetti",
"Fabio Marton",
"Federico Ponchio",
"Roberto Scopigno"
] | [] | [] | [] |
Vis | 2,003 | Producing high-quality visualizations of large-scale simulation | 10.1109/VISUAL.2003.1250422 | This paper describes the work of a team of researchers in computer graphics, geometric computing, and civil engineering to produce a visualization of the September 2001 attack on the Pentagon. The immediate motivation for the project was to understand the behavior of the building under the impact. The longer term motivation was to establish a path for producing high-quality visualizations of large scale simulations. The first challenge was managing the enormous complexity of the scene to fit within the limits of state-of-the art simulation software systems and supercomputing resources. The second challenge was to integrate the simulation results into a high-quality visualization. To meet this challenge, we implemented a custom importer that simplifies and loads the massive simulation data in a commercial animation system. The surrounding scene is modeled using image-based techniques and is also imported in the animation system where the visualization is produced. A specific issue for us was to federate the simulation and the animation systems, both commercial systems not under our control and following internally different conceptualizations of geometry and animation. This had to be done such that scalability was achieved. The reusable link created between the two systems allows communicating the results to non-specialists and the public at large, as well as facilitating communication in teams with members having diverse technical backgrounds. | false | false | [
"Voicu Popescu",
"Christoph M. Hoffmann",
"Sami Kilic",
"Mete Sozen",
"Scott Meador"
] | [] | [] | [] |
Vis | 2,003 | Psychophysical scaling of a cardiovascular information display | 10.1109/VISUAL.2003.1250352 | A new method was developed to increase the saliency of changing variables in a cardiovascular visualization for use by anesthesiologists in the operating room (OR). Clinically meaningful changes in patient physiology were identified and then mapped to the inherent psychophysical properties of the visualization. A long history of psychophysical research has provided an understanding of the parameters within which the human information processing system is able to detect changes in the size, shape and color of visual objects (Gescheider, 1976, Spence, 1990, and Baird, 1970). These detection thresholds are known as just noticeable differences (JNDs) which characterize the amount of change in an object's attribute that is recognizable 50% of the time. A prototype version of the display has been demonstrated to facilitate anesthesiologist's performance while reducing cognitive workload during simulated cardiac events (Agutter et al., 2002). In order to further improve the utility of the new cardiovascular visualization, the clinically relevant changes in cardiovascular variables are mapped to noticeable perceptual changes in the representational elements of the display. The results of the method described in this paper are used to merge information from the psychophysical properties of the cardiovascular visualization, with clinically relevant changes in the patient's cardiovascular physiology as measured by the clinical meaningfulness questionnaire. The result of this combination will create a visualization that is sensitive to changes in the cardiovascular health of the patient and communicates this information to the user in a meaningful, salient and intuitive manner. | false | false | [
"Robert Albert",
"Noah Syroid",
"Yinqi Zhang",
"James Agutter",
"Frank Drews",
"David L. Strayer",
"George Hutchinson",
"Dwayne R. Westenskow"
] | [] | [] | [] |
Vis | 2,003 | Quasi-static approach approximation for 6 degrees-of-freedom haptic rendering | 10.1109/VISUAL.2003.1250380 | In this paper, we propose a quasi-static approximation (QSA) approach to simulate the movement of the movable object in 6-degrees-of-freedom (DOF) haptic rendering. In our QSA approach, we solve for static equilibrium during each haptic time step, ignoring any dynamical properties such as inertia. The major contribution of this approach is to overcome the computational instability problem in overly stiff systems arising from numerical integration of second-order differential equations in previous dynamic models. Our primary experimental results on both simulated aircraft geometry and a large-scale real-world aircraft engine showed that our QSA approach was capable of maintaining the 1000Hz haptic refresh rate with more robust collision avoidance and more reliable force and torque feedback. | false | false | [
"Ming Wan",
"William A. McNeely"
] | [] | [] | [] |
Vis | 2,003 | Real-time refinement and simplification of adaptive triangular meshes | 10.1109/VISUAL.2003.1250367 | In this paper we present a generic method for incremental mesh adaptation based on hierarchy of semi-regular meshes. Our method supports any refinement rule mapping vertices onto vertices such as 1-to-4 split or /spl radic/3-subdivision. Resulting adaptive mesh has subdivision connectivity and hence good aspect ratio of triangles. Hierarchic representation of the mesh allows incremental local refinement and simplification operations exploiting frame-to-frame coherence. We also present an out-of-core storage layout scheme designed for semi-regular meshes of arbitrary subdivision connectivity. It provides high cache coherency in the data retrieval and relies on the interleaved storage of resolution levels and maintaining good geometrical proximity within each level. The efficiency of the proposed method is demonstrated with applications in physically-based cloth simulation, real-time terrain visualization and procedural modeling. | false | false | [
"Vasily Volkov",
"Ling Li 0006"
] | [] | [] | [] |
Vis | 2,003 | Saddle connectors - an approach to visualizing the topological skeleton of complex 3D vector fields | 10.1109/VISUAL.2003.1250376 | One of the reasons that topological methods have a limited popularity for the visualization of complex 3D flow fields is the fact that such topological structures contain a number of separating stream surfaces. Since these stream surfaces tend to hide each other as well as other topological features, for complex 3D topologies the visualizations become cluttered and hardly interpretable. This paper proposes to use particular stream lines called saddle connectors instead of separating stream surfaces and to depict single surfaces only on user demand. We discuss properties and computational issues of saddle connectors and apply these methods to complex flow data. We show that the use of saddle connectors makes topological skeletons available as a valuable visualization tool even for topologically complex 3D flow data. | false | false | [
"Holger Theisel",
"Tino Weinkauf",
"Hans-Christian Hege",
"Hans-Peter Seidel"
] | [] | [] | [] |
Vis | 2,003 | Shape simplification based on the medial axis transform | 10.1109/VISUAL.2003.1250410 | We present a new algorithm for simplifying the shape of 3D objects by manipulating their medial axis transform (MAT). From an unorganized set of boundary points, our algorithm computes the MAT, decomposes the axis into parts, then selectively removes a subset of these parts in order to reduce the complexity of the overall shape. The result is simplified MAT that can be used for a variety of shape operations. In addition, a polygonal surface of the resulting shape can be directly generated from the filtered MAT using a robust surface reconstruction method. The algorithm presented is shown to have a number of advantages over other existing approaches. | false | false | [
"Roger C. Tam",
"Wolfgang Heidrich"
] | [] | [] | [] |
Vis | 2,003 | Signed distance transform using graphics hardware | 10.1109/VISUAL.2003.1250358 | This paper presents a signed distance transform algorithm using graphics hardware, which computes the scalar valued function of the Euclidean distance to a given manifold of co-dimension one. If the manifold is closed and orientable, the distance has a negative sign on one side of the manifold and a positive sign on the other. Triangle meshes are considered for the representation of a two-dimensional manifold and the distance function is sampled on a regular Cartesian grid. In order to achieve linear complexity in the number of grid points, to each primitive we assign a simple polyhedron enclosing its Voronoi cell. Voronoi cells are known to contain exactly all points that lay closest to its corresponding primitive. Thus, the distance to the primitive only has to be computed for grid points inside its polyhedron. Although Voronoi cells partition space, the polyhedrons enclosing these cells do overlap. In regions where these overlaps occur, the minimum of all computed distances is assigned to a grid point. In order to speed up computations, points inside each polyhedron are determined by scan conversion of grid slices using graphics hardware. For this task, a fragment program is used to perform the nonlinear interpolation and minimization of distance values. | false | false | [
"Christian Sigg",
"Ronald Peikert",
"Markus H. Gross"
] | [] | [] | [] |
Vis | 2,003 | Space efficient fast isosurface extraction for large datasets | 10.1109/VISUAL.2003.1250373 | In this paper, we present a space efficient algorithm for speeding up isosurface extraction. Even though there exist algorithms that can achieve optimal search performance to identify isosurface cells, they prove impractical for large datasets due to a high storage overhead. With the dual goals of achieving fast isosurface extraction and simultaneously reducing the space requirement, we introduce an algorithm based on transform coding to compress the interval information of the cells in a dataset. Compression is achieved by first transforming the cell intervals (minima, maxima) into a form which allows more efficient compaction. It is followed by a dataset optimized non-uniform quantization stage. The compressed data is stored in a data structure that allows fast searches in the compression domain, thus eliminating the need to retrieve the original representation of the intervals at run-time. The space requirement of our search data structure is the mandatory cost of storing every cell ID once, plus an overhead for quantization information. The overhead is typically in the order of a few hundredths of the dataset size. | false | false | [
"Udeepta Bordoloi",
"Han-Wei Shen"
] | [] | [] | [] |
Vis | 2,003 | The visualization market: open source vs. commercial approaches | 10.1109/VISUAL.2003.1250350 | This forum examines the question of when commercial software makes sense and when open-source software is more appropriate. Visualization software runs the gamut from very general-purpose applications intended for the graphically challenged to highly specific software libraries intended for the sophisticated visualization expert. Where along that spectrum is the realm of commercial software, and where does open-source software make sense? Should all visualization software be open source? Why might end users choose to purchase visualization tools instead of using opensource tools? | false | false | [
"Jeremy Jaech",
"Stephen C. North",
"Mike Peery",
"Will Schroeder",
"James J. Thomas"
] | [] | [] | [] |
Vis | 2,003 | Using deformations for browsing volumetric data | 10.1109/VISUAL.2003.1250400 | Many traditional techniques for "looking inside" volumetric data involve removing portions of the data, for example using various cutting tools, to reveal the interior. This allows the user to see hidden parts of the data, but has the disadvantage of removing potentially important surrounding contextual information. We explore an alternate strategy for browsing that uses deformations, where the user can cut into and open up, spread apart, or peel away parts of the volume in real time, making the interior visible while still retaining surrounding context. We consider various deformation strategies and present a number of interaction techniques based on different metaphors. Our designs pay special attention to the semantic layers that might compose a volume (e.g. the skin, muscle, bone in a scan of a human). Users can apply deformations to only selected layers, or apply a given deformation to a different degree to each layer, making browsing more flexible and facilitating the visualization of relationships between layers. Our interaction techniques are controlled with direct, "in place" manipulation, using pop-up menus and 3D widgets, to avoid the divided attention and awkwardness that would come with panels of traditional widgets. Initial user feedback indicates that our techniques are valuable, especially for showing portions of the data spatially situated in context with surrounding data. | false | false | [
"Michael J. McGuffin",
"Liviu Tancau",
"Ravin Balakrishnan"
] | [] | [] | [] |
Vis | 2,003 | Vicinity shading for enhanced perception of volumetric data | 10.1109/VISUAL.2003.1250394 | This paper presents a shading model for volumetric data which enhances the perception of surfaces within the volume. The model incorporates uniform diffuse illumination, which arrives equally from all directions at each surface point in the volume. This illumination is attenuated by occlusions in the local vicinity of the surface point, resulting in shadows in depressions and crevices. Experiments by other authors have shown that perception of a surface is superior under uniform diffuse lighting, compared to illumination from point source lighting. | false | false | [
"A. James Stewart"
] | [] | [] | [] |
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