By Topic

Visualization and Computer Graphics, IEEE Transactions on

Issue 2 • Date April-June 2003

Filter Results

Displaying Results 1 - 13 of 13
  • Guest editor's introduction: special section on IEEE visualization

    Page(s): 113 - 114
    Save to Project icon | Request Permissions | PDF file iconPDF (183 KB)  
    Freely Available from IEEE
  • GraphSplatting: visualizing graphs as continuous fields

    Page(s): 206 - 212
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (726 KB)  

    This paper introduces GraphSplatting, a technique which transforms a graph into a two-dimensional scalar field. The scalar field can be rendered as a color coded map, a height field, or a set of contours. Splat fields allow for the visualization of arbitrarily large graphs without cluttering. They provide density information which can be used to determine the structure of the graph. The construction, visualization, and interaction with splat fields is discussed. Two applications illustrate the usage of GraphSplatting. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comparing simplification and image-based techniques for 3D client-server rendering systems

    Page(s): 226 - 240
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1290 KB)  

    A mathematical model is presented for comparing geometric and image-based simplification methods. Geometric simplification reduces the number of polygons in the virtual object and image-based simplification replaces the object with an image. Our model integrates and extrapolates existing accuracy estimates, enabling the comparison of different simplification methods in order to choose the most efficient method in a given situation. The model compares data transfer and rendering load of the methods. Byte size and expected lifetime of simplifications are calculated as a function of the desired visual quality and the position and movement of the viewer. An example result is that, in typical viewing and rendering conditions and for objects with a radius in the order of one meter, imposter techniques can be used at viewing distances above 15 meters. Below that, simplified polygon objects are required and, below one meter distance, the full-resolution virtual object has to be rendered. An electronic version of the model is available on the web. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Multiscale visualization using data cubes

    Page(s): 176 - 187
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2940 KB)  

    Most analysts start with an overview of the data before gradually refining their view to be more focused and detailed. Multiscale pan-and-zoom systems are effective because they directly support this approach. However, generating abstract overviews of large data sets is difficult and most systems take advantage of only one type of abstraction: visual abstraction. Furthermore, these existing systems limit the analyst to a single zooming path on their data and thus to a single set of abstract views. This paper presents: 1) a formalism for describing multiscale visualizations of data cubes with both data and visual abstraction and 2) a method for independently zooming along one or more dimensions by traversing a zoom graph with nodes at different levels of detail. As an example of how to design multiscale visualizations using our system, we describe four design patterns using our formalism. These design patterns show the effectiveness of multiscale visualization of general relational databases. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Using motion to illustrate static 3D shape-kinetic visualization

    Page(s): 115 - 126
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1344 KB)  

    In this paper, we present a novel visualization technique-kinetic visualization-that uses motion along a surface to aid in the perception of 3D shape and structure of static objects. The method uses particle systems, with rules such that particles flow over the surface of an object to not only bring out, but also attract attention to information on a shape that might not be readily visible with a conventional rendering method which uses lighting and view changes. Replacing still images with animations in this fashion, we demonstrate with both surface and volumetric models in the accompanying videos that, in many cases, the resulting visualizations effectively enhance the perception of three-dimensional shape and structure. We also describe how, for both types of data, a texture-based representation of this motion can be used for interactive visualization using PC graphics hardware. Finally, the results of a user study that we have conducted are presented, which show evidence that the supplemental motion cues can be helpful. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Distributed Virtual Reality environments based on rewriting systems

    Page(s): 213 - 225
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1474 KB)  

    Ideally, virtual worlds should be dynamic, mutable, and complex in order to be attractive for immersed users. As such worlds can be designed easily by rewriting techniques, we propose a distributed Virtual Reality (VR) system that is based on an interactive animation system using a rewriting technique for geometric and behavioral modeling. The emphasis is on concepts and extensions for the integration of user immersion, user interaction, and networking into a rewriting-based animation system, Finally, the modeling of a ball game with two immersed users, as well as a virtual park, serve as case studies to illustrate the proposed concepts and extensions. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Hardware-based view-independent cell projection

    Page(s): 163 - 175
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1049 KB)  

    We present two implementations of a view-independent cell projection algorithm for off-the-shelf programmable graphics hardware. Both implementations perform all computations for the projection and scan conversion of a set of tetrahedra on the graphics hardware and are therefore compatible with many of the hardware-accelerated optimizations for polygonal graphics, e.g., OpenGL vertex arrays and display lists. Apart from our actual implementations, we discuss potential improvements on future, more flexible graphics hardware and applications to interactive volume visualization of unstructured meshes. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Simplification and repair of polygonal models using volumetric techniques

    Page(s): 191 - 205
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1439 KB)  

    Two important tools for manipulating polygonal models are simplification and repair and we present voxel-based methods for performing both of these tasks. We describe a method for converting polygonal models to a volumetric representation in a way that handles models with holes, double walls, and intersecting parts. This allows us to perform polygon model repair simply by converting a model to and from the volumetric domain. We also describe a new topology-altering simplification method that is based on 3D morphological operators. Visually unimportant features such as tubes and holes may be eliminated from a model by the open and close morphological operators. Our simplification approach accepts polygonal models as input, scan converts these to create a volumetric description, performs topology modification, and then converts the results back to polygons. We then apply a topology-preserving polygon simplification technique to produce a final model. Our simplification method produces results that are everywhere manifold. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Shadows and soft shadows with participating media using splatting

    Page(s): 139 - 149
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1074 KB)  

    This paper describes an efficient algorithm to model the light attenuation due to a participating media with low albedo. Here, we consider the light attenuation along a ray, as well as the light attenuation emanating from a surface. The light attenuation is modeled using a splatting volume renderer for both the viewer and the light source. During the rendering, a 2D shadow buffer accumulates the light attenuation. We first summarize the basic shadow algorithm using splatting. Then, an extension of the basic shadow algorithm for projective textured light sources is described. The main part of this paper is an analytic soft shadow algorithm based on convolution techniques. We describe and discuss the soft shadow algorithm, and generate soft shadows, including umbra and penumbra, for extended light sources. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A model for volume lighting and modeling

    Page(s): 150 - 162
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2375 KB)  

    Direct volume rendering is a commonly used technique in visualization applications. Many of these applications require sophisticated shading models to capture subtle lighting effects and characteristics of volumetric data and materials. For many volumes, homogeneous regions pose problems for typical gradient-based surface shading. Many common objects and natural phenomena exhibit visual quality that cannot be captured using simple lighting models or cannot be solved at interactive rates using more sophisticated methods. We present a simple yet effective interactive shading model which captures volumetric light attenuation effects that incorporates volumetric shadows, an approximation to phase functions, an approximation to forward scattering, and chromatic attenuation that provides the subtle appearance of translucency. We also present a technique for volume displacement or perturbation that allows realistic interactive modeling of high frequency detail for both real and synthetic volumetric data. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Illustrative interactive stipple rendering

    Page(s): 127 - 138
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3890 KB)  

    Simulating hand-drawn illustration can succinctly express information in a manner that is communicative and informative. We present a framework for an interactive direct stipple rendering of volume and surface-based objects. By combining the principles of artistic and scientific illustration, we explore several feature enhancement techniques to create effective, interactive visualizations of scientific and medical data sets. We also introduce a rendering mechanism that generates appropriate point lists at all resolutions during an automatic preprocess and modifies rendering styles through different combinations of these feature enhancements. The new system is an effective way to interactively preview large, complex volume and surface data sets in a concise, meaningful, and illustrative manner. Stippling is effective for many applications and provides a quick and efficient method to investigate both volume and surface models. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Image-based techniques in a hybrid collision detector

    Page(s): 254 - 271
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1674 KB)  

    Most collision detection methods developed so far are based on geometrical object-space interference tests. While this remains the basic mode of investigation for geometric algorithms, the requirements for interactive rates and complex geometry predominate in commercial applications. In this article, we propose a new mode of collision detection based on an image-space approach. This approach breaks the object-space collision detection bottleneck by distributing the computational load onto the hardware graphics pipeline. The image-space approach, in conjunction with efficient bounding-box strategies in the object-space, has the potential to handle complex object interactions at interactive rates. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Communicating centrality in policy network drawings

    Page(s): 241 - 253
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (936 KB)  

    We introduce a network visualization technique that supports an analytical method applied in the social sciences. Policy network analysis is an approach to study policy making structures, processes, and outcomes, thereby concentrating on relations between policy actors. An important operational concept for the analysis of policy networks is the notion of centrality, i.e., the distinction of actors according to their importance in a relational structure. We integrate this measure in a layout model for networks by mapping structural to geometric centrality. Thus, centrality values and network data can be presented simultaneously and explored interactively. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

Visualization techniques and methodologies; visualization systems and software; volume visualization; flow visualization; multivariate visualization; modeling and surfaces; rendering; animation; user interfaces; visual progranuning; applications.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Ming Lin
Department of Computer Science
University of North Carolina