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Scientific Visualization Conference, 1997

Date 9-13 June 1997

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Displaying Results 1 - 25 of 38
  • Preface

    Page(s): viii
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    Freely Available from IEEE
  • An Edge-Preserving, Data-Dependent Triangulation Scheme for Hierarchical Rendering

    Page(s): 1
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    In many applications one is concerned with the approximation of functions from a finite set of given data sites with associated function values. We describe a construction of a hierarchy of triangulations which approximate the given data at varying levels of detail. Intermediate triangulations can be associated with a particular level of the hierarchy by considering their approximation errors. This paper presents a new data-dependent triangulation scheme for multi-valued scattered data in the plane. We perform piecewise linear approximation based on data-dependent triangulations. Our scheme preserves edges (discontinuities) that might exist in a given data set by placing vertices close to edges. We start with a coarse, data-dependent triangulation of the convex hull of the given data sites and subdivide triangles until the error of the piecewise linear approximation implied by a triangulation is smaller than some tolerance. View full abstract»

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  • A Hybrid Web-Based Toolkit for Human Modeling

    Page(s): 11
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    Modern web-based Scientific Visualization applications try to overcome common limitations imposed by limited internet bandwidth, server bottlenecks or network latency. A further aspect is the desire to gain platform independence by solely using instruments which are platform independent by conception: the programming language Java, the Virtual Reality Modeling Language (VRML), or the 3D API Java3D.We present a prototype of a hybrid web-based Scientific Visualization system which makes use of the increasing computational power of modern desktop workstations and personal computers on the client side, and the superior performance provided by a powerful machine on the server side. In order to achieve high interaction rates and to balance computational load the user can dynamically assign selected tasks to his client or to the server.Within the scientific field of human modeling we have implemented a hybrid web-based toolkit for the modeling of human muscles and skin. Our application allows the on-line generation and manipulation of three-dimensional implicit muscle models in a heterogeneous network and it offers various parameters to adjust computation and response time versus rendering quality. View full abstract»

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  • An Introduction to Wavelets for Scientific Visualization

    Page(s): 16
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    This paper gives an introduction to wavelet techniques in the context of Scientific Visualization. Wavelets are a powerful tool for the representation of large and complex data sets. Some restrictions apply on the type of data sets which can be represented by wavelets. These restrictions are described in a first part. Thereafter, the basic concepts of wavelet representations are explained: level of detail spaces, wavelet spaces, decomposition and reconstruction algorithms. Orthogonality properties of wavelets and their relations with the ability of computing best approximations are the subject of the next part. Usual applications of wavelet representations in Scientific Visualization are then reviewed. These include progressive transmission, LOD visualization, local area zooming. The last part is dedicated to a recent generalization of wavelet techniques that deals with some types of data sets that cannot be tackle by usual wavelet representations due to the restrictions described in the first part. View full abstract»

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  • Visualization over the World Wide Web

    Page(s): 23
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    The Web has grown from being a global information repository into a worldwide distributed computing environment. This offers the opportunity to carry out data visualization as a Web-based application. In this paper we look at the different players involved in the creation of a Web-based visualization service, and hence build a reference model for Web-based visualization. we then use this model to identify three distinct system architectures for Web-based visualization. We illustrate each architecture with corresponding examples of visualization services. View full abstract»

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  • Simple, Fast, and Robust Ray Casting of Irregular Grids

    Page(s): 30
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    In this paper we describe a simple and efficient ray casting engine that is suitable for the rapid exploration of irregular grids composed of tetrahedra cells, or other cell complexes where cells have been broken up into faces. In our method, in a preprocessing phase, all the cells are broken into their corresponding faces. Visibility determination is performed after all the faces have been transformed into screen space; here we compute for each pixel an ordered list of the stabbing boundary faces. The final phase is the actual ray casting, which is performed independently for each pixel, and is basically a walk in the cell complex inside each component of the stabbing ordered list. For color calculations, a simple analytical lighting model is applied to each intersection of ray and cell. Our algorithm is simple, and our implementation fast and robust. View full abstract»

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  • An Integrated VR- and Simulation-Environment for Supporting the Complete Product Life Cycle of Space-Related Systems

    Page(s): 37
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    System development life cycles have been shortened within the last years using enhanced computer-based tools. Each life cycle of a system has been separated from later cycles of other systems except for the common knowledge of developers involved in different phases. To enhance the process of developing and bringing a product to the market from scratch we integrate available tools and information into a single development environment which improves the performance of the complete development team. We will show in this paper how VR- and simulation- tools can be combined to improve the development process of a product. In doing this we will especially focus on the reuse of knowledge gathered in previous phases of the development cycle or even gathered in former projects. The use of virtual reality tools for visualization and interaction in different phases is discussed. Finally we present an approach that is currently under development at DaimlerChrysler Aerospace Space-Infrastructure Division. View full abstract»

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  • Spotting Structure in Complex Time Dependent Flow

    Page(s): 47
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    Analyzing structure in complex time dependent flow fields is a challenging problem. This paper describes the use of spot noise for the visualization of this type of fields. Spot noise is a technique which utilizes texture for the visualization of flow fields. In this paper, two extensions of spot noise are discussed. These extensions allow spot noise to be used for detailed analysis of time dependent flow fields. In addition, two cases are discussed: a large data set resulting from a direct numerical simulation of turbulence and a data set resulting from a global climate measurements. View full abstract»

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  • Multiresolutional Visualization of Evolving Distributed Simulations Using Wavelets and MPI

    Page(s): 54
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    This paper presents a technique to losslessly compress and progressively transmit floating point data using wavelets. MPI (Message Passing Interface) is employed in the implementation of this technique so that the parallelized solver which runs in a remote computing environment and the visualization tool which runs on a local graphics workstation can communicate. View full abstract»

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  • Solid Fitting: Field Interval Analysis for Effective Volume Exploration

    Page(s): 65
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    In previous reports, the concept of solid fitting has been presented as a new indirect approach to volume visualization. Solid fitting relies on a simple, but powerful geometric data model, termed interval volume, that allows one to represent a three-dimensional subvolume for which the associated scalar values lie within a specified closed interval. This paper combines the latest results obtained through the course of the solid fitting project. After reviewing the salient features of interval volume and the fundamentals of solid fitting in the first two sections, Section 3 discusses improvements to the original solid fitting algorithm so as to extract interval volumes in a topologically-consistent manner. Also, the octree-based acceleration mechanism incorporated into the algorithm is analyzed further with a complex, time-evolving, volumetric data set. Section 4 is devoted to the presentation of several representative operations related to interval volume, including focusing and measurement-coupled visualization. In addition, a candidate for the volumetric coherence measure is introduced for adaptive solid fitting and its application to multi-scalar visualization. Lastly, Section 5 summarized the paper with some remarks on a hybrid volume exploration environment, in which solid fitting plays various roles. View full abstract»

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  • Visualization of Analytically Defined Dynamical Systems

    Page(s): 71
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    The visualization of analytically defined dynamical systems is important for a thorough understanding of the underlying system behavior. An overview of theoretical concepts concerning analytically defined dynamical systems is given. Various visualization techniques for dynamical systems are discussed. Three current research directions concerning the visualization of dynamical systems are treated in more detail. These are: texture based techniques, visualization of high-dimensional dynamical systems, and advanced streamsurface representations. View full abstract»

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  • Wiener Splines

    Page(s): 83
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    We describe an alternative way of constructing interpolating B-spline curves, surfaces or volumes in Fourier space which can be used for visualization. In our approach the interpolation problem is considered from a signal processing point of view and is reduced to finding an inverse B-spline filter sequence. The Fourier approach encompasses some advantageous features, such as successive approximation, compression, fast convolution and hardware support. In addition, optimal Wiener filtering can be applied to remove noise and distortions from the initial data points and to compute a smooth, least-squares fitting "lq Wiener spline". Unlike traditional fitting methods, the described algorithm is simple and easy to implement. The performance of the presented method is illustrated by some examples showing the restoration of surfaces corrupted by various types of distortions. View full abstract»

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  • Constrained Navigation Environments

    Page(s): 95
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    Finding one's way through a complex virtual environment is a standard task in 3D graphics and virtual reality applications. Constrained navigation is a method that appropriately restricts the user's degrees of freedom when there is a poor match between the goal of an exploration activity, the control device, and the user's familiarity with the exploration domain. The fundamental prerequisite for the adoption of constrained navigation is that the designer can significantly improve the quality of the user's experience by choosing a predetermined parametric set of viewing parameters or algorithms. We discuss families of constrained navigation methods appropriate to desktop and immersive virtual reality applications. We illustrate the approach with a variety of examples, emphasizing the possibility of topologically nontrivial navigation spaces, and present the results of a preliminary user study. View full abstract»

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  • Cluster-Based Generation of Hierarchical Surface Models

    Page(s): 105
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    We present a highly efficient, automatic method for the generation of hierarchical surface triangulations. Given a set of scattered points in three-dimensional space, without known connectivity information, our method reconstructs a valid triangulated surface model in a two-step procedure. First, we apply clustering to the set of given points and identify point subsets in locally nearly planar regions. Second, we construct a surface triangulation from the output of the clustering step. The output of the clustering step is a set of 2-manifold tiles, which locally approximate the underlying, unknown surface. We construct the triangulation of the entire surface by triangulating the individual tiles and triangulating the gaps between the tiles. Since we apply point clustering in a hierarchical fashion we can generate model hierarchies by triangulating various levels resulting from the hierarchical clustering step. View full abstract»

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  • The VisAD Java Class Library for Scientific Data and Visualization

    Page(s): 115
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    VisAD is a Java class library for interactive and collaborative visualization and analysis of numerical data. It is designed to support distributed computing and data sharing on the Internet through the use of distributed objects and a very general numerical data model. The data model integrates metadata for data organization, units, coordinate systems, sampling geometries and topoligies, missing data indicators, and error estimates. When data are combined in computations or visualizations, unit conversion, coordinate transforms and resampling are done implicitly as needed. View full abstract»

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  • Notes on Computational-Space-Based Ray-Casting for Curvilinear Volumes

    Page(s): 124
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    In this paper we study the computational-space-based (C-space-based) ray-casting algorithm for rendering curvilinear volumes. With a simple counter example, we demonstrate that a proposed C-space-based method may not generate rendering results as accurately as ray-casting in the physical space. We also analyze what needs to be improved and discuss several other issues related to the C-space-based approach. View full abstract»

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  • LIC For Surface Flow Feature Detection

    Page(s): 130
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    The Line Integral Convolution (LIC) algorithm has received a lot of attention and interest. Yet, only a few of the current LIC related algorithms deal specifically with color textures for automatic detection of flow features. In this paper, I give a brief review of current work in this area. View full abstract»

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  • Ray-Based Data Level Comparisons of Direct Volume Rendering Algorithms

    Page(s): 137
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    We present a new method for comparing direct volume rendering (DVR) algorithms. The motivations for this work are: the prevalence of DVR algorithms that produce slightly different images from the same data set and viewing parameters, and the limitations of existing image level comparison methods. In this paper, we describe and demonstrate the effectiveness of several ray-based metrics for data level comparison of direct volume rendering (DVR) algorithms. Unlike other papers on DVR, the focus of this paper is not on speed ups from approximations or implementations with parallel or specialized hardware, but rather on methods for comparison. However, unlike image level comparisons, where the starting point is 2D images, the main distinction of data level comparison is the use of intermediate 3D information to produce the individual pixel values during the rendering process. In addition to identifying the location and extent of differences in DVR images, these data level comparisons allow us to explain why these differences arise from different DVR algorithms. Because of the rich variety of DVR algorithms, finding a common framework for developing data level comparison metrics is one of the main challenges and contribution of this paper. In this paper, we report on how ray tracing can be used as a common framework for comparing a class of DVR algorithms. View full abstract»

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  • Visualization of Complex Physical Phenomena and Mathematical Objects in Virtual Environment

    Page(s): 151
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    In this paper we present a several topics in visualization and animation of topologically non-trivial objects: the open strings in 3D space; a process of un-coupling of 2 coupled handles on a sphere in 3D space by means of a homotopy in the class of embedding; the projective plane and the projective 3D space. Various properties of these objects are visualized: their non-orientability and non-trivial connectivity, and two representations of the projective plane in 3D space are examined: the cross-cap and the Boy immersion.Visualization in string theory and some results obtained from visual study of strings demonstrates the benefits of this approach.Problems are discussed that arise in computer assisted visualization of topologically non-trivial objects, and in their integration in virtual environments, in particular: fast rendering of self-crossing transparent surfaces, and smooth mapping of colors and textures onto topologically complex surfaces. View full abstract»

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  • Using Virtual Reality to Visualize Scientific, Engineering, and Medical Data

    Page(s): 161
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    In this paper we briefly discuss the state of the art of Virtual Reality as applied to visualization of scientific and technical data sets. We describe the technologies and software for the creation of Virtual Environments. We also give an overview of some of the more significant and successful Virtual Reality applications in the fields of medicine, engineering, chemistry and computational fluid dynamics. View full abstract»

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  • Fast and Accurate Collision Detection for Virtual Environments

    Page(s): 171
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    A realistic simulation system, which couples geometry and physics, can provide a useful toolkit for virtual environments. Interactions among moving objects in the virtual worlds are modeled by dynamic constraints and contact analysis. In order to portray the geometric interaction in a dynamical system or to simulate physical behaviors of entities in the virtual environments, it is essential to perform collision detection at interactive rate with minimal computation possible. In this paper, we present efficient algorithms for contact determination and interference detection between geometric models undergoing rigid motion. The set of models includes polyhedra and surfaces described by B-splines. The algorithms make use of temporal and spatial coherence between successive instances to reduce the number of pairwise tests and hierarchical data structures for checking overlaps between a pair of objects. Their running time is a function of the motion between successive instances. The main characteristics of these algorithms are their simplicity and efficiency. They have been implemented. A subset of these implementations, including I-Collide, RAPID and V-Collide are available as part of the collision detection packages at the UNC-CH website. View full abstract»

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  • Scattered Data Techniques for Surfaces

    Page(s): 181
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    This survey presents several techniques for solving variants of the following scattered data interpolation problem: given a finite set of N points in R3, find a surface that interpolates the given set of points. Problems of this variety arise in numerous areas of applications such as geometric modeling and scientific visualization. A large class of solutions exists for these problems and many excellent surveys exist as well.The focus of this survey is on presenting techniques that are relatively recent. Some discussion of two popular variants of the scattered data interpolation problem -- trivariate (or volumetric) case and surface-on-surface -- is also included.Solutions are classified into one of the five categories: piecewise polynomial or rational parametric solutions, algebraic solutions, radial basis function methods, Shepard's methods and subdivision surfaces. Discussion on parametric solutions includes global interpolation by a single polynomial, interpolants based on data dependent triangulations, piecewise linear solutions such as alpha-shapes, and interpolants on irregular mesh.Algebraic interpolants based on cubic A-patches are described. Interpolants based on radial basis functions include Hardy's multiquadrics, inverse multiquadrics and thin plate splines. Techniques for blending local solutions and natural neighbor interpolants are described as variations of Shepard's methods. Subdivision techniques include Catmull-Clark subdivision technique and its variants and extensions. A brief discussion on surface interrogation techniques and visualization techniques is also included. View full abstract»

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  • Interpolation and Approximation of Surfaces from Three-Dimensional Scattered Data Points

    Page(s): 223
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    There is a wide range of applications for which surface interpolation or approximation from scattered data points in space is important. Dependent on the field of application and the related properties of the data, many algorithms were developed in the past. This contribution gives a survey of existing algorithms, and identifies basic methods common to independently developed solutions. We distinguish surface construction based on spatial subdivision, distance functions, warping, and incremental surface growing. The systematic analysis of existing approaches leads to several interesting open questions for further research. View full abstract»

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  • InVIS - Interactive Visualization of Medical Data Sets

    Page(s): 233
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    Interactive rendering of large data sets requires efficient algorithms and accelerated graphics hardware. Both efficiency and speed can be improved, but none of these alone guarantees interactive response time. If a scene is too complex, performance decreases, and neither faster algorithms nor speeding up hardware can ensure interactive performance. This means that certain timing characteristics need to be incorporated in order to obtain interactive behavior.In this paper we propose a new approach to interactive rendering by introducing a rendering pipeline with special timing predicates. We use this technique for applications in the field of medical imaging. Large data sets derived from CT or MRI scans and CAD designs must be rendered in real-time. The system should provide immediate feedback to the user. Interactive behavior enables the user to manipulate and adjust the image straight on demand. View full abstract»

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  • Surface Reconstruction - An Introduction

    Page(s): 239
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    The goal of surface reconstruction is to find a surface from a given finite set of geometric sample values. In many applications, the sample values are points. But other types of samples, like curves occurring e.g. in tactile sampling by an adapted milling machine, or volume densities occurring for instance in X-ray based computer tomography, are also possible. We illuminate different aspects of the problem and give a brief survey of the work performed in the past. View full abstract»

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