IEEE VIS Publication Dataset

Cortex has been designed for interactive analysis and display of simulation data generated by CFD applications based on unstructured-grid solvers. Unlike post-processing visualization environments, Cortex is designed to work in co-processing mode with the CFD application. This significantly reduces data storage and data movement requirements for visualization and also allows users to interactively steer the application. Further, Cortex supports high-performance by running on massively parallel computers and workstation clusters. An important goal for Cortex, is to provide visualization to a variety of solvers which differ in their solution methodologies and supported flow models. Coupled with the co-processing requirement, this has required the development of a well defined programming interface to the CFD solver that lets the visualization system communicate efficiently with the solver, and requires minimal programming effort for porting to new solvers. Further, the requirement for targeting multiple solvers and application niches demands that the visualization system be rapidly and easily modifiable. Such flexibility is attained in Cortex by using the high-level, interpreted language Scheme for implementing user-interfaces and high-level visualization functions. By making the Scheme interpreter available from the Cortex text interface, the user can also customize and extend the visualization system

We study the topology of symmetric, second-order tensor fields. The goal is to represent their complex structure by a simple set of carefully chosen points and lines analogous to vector field topology. We extract topological skeletons of the eigenvector fields, and we track their evolution over time. We study tensor topological transitions and correlate tensor and vector data. The basic constituents of tensor topology are the degenerate points, or points where eigenvalues are equal to each other. Degenerate points play a similar role as critical points in vector fields. We identify two kinds of elementary degenerate points, which we call wedges and trisectors. They can combine to form more familiar singularities-such as saddles, nodes, centers, or foci. However, these are generally unstable structures in tensor fields. Finally, we show a topological rule that puts a constraint on the topology of tensor fields defined across surfaces, extending to tensor fields the Poincare-Hopf theorem for vector fields

One of the most fundamental issues in magnetic fusion research is the understanding of turbulent transport observed in present-day tokamak experiments. Plasma turbulence is very challenging from a theoretical point of view due to the nonlinearity and high dimensionality of the governing equations. Recent developments in algorithms along with the astounding advances in high performance computing now make first-principle particle simulations an important tool for improved understanding of such phenomena. Due to the five dimensional phase space (3 spatial, 2 velocity) and complex toroidal geometry, visualization is crucial for interpreting such simulation data. This paper discusses how visualization tools are currently used and what new physics has been elucidated, along with what can be learned about tokamak turbulence through the interplay between theory, simulation and visualization

We present a comprehensive algorithm to construct a topologically correct triangulation of the real affine part of a rational parametric surface with few restrictions on the defining rational functions. The rational functions are allowed to be undefined on domain curves (pole curves) and at certain special points (base points), and the surface is allowed to have nodal or cuspidal self-intersections. We also recognize that for a complete display, some real points on the parametric surface may be generated only by complex parameter values, and that some finite points on the surface may be generated only by infinite parameter values; we show how to compensate for these conditions. Our techniques for handling these problems have applications in scientific visualization, rendering non-standard NURBS, and in finite-element mesh generation

Time-dependent (unsteady) flow fields are commonly generated in computational fluid dynamics (CFD) simulations; however, there are very few flow visualization systems that generate particle traces in unsteady flow fields. Most existing systems generate particle traces in time-independent flow fields. A particle tracing system has been developed to generate particle traces in unsteady flow fields. The system was used to visualize several 3D unsteady flow fields from real-world problems, and it has provided useful insights into the time-varying phenomena in the flow fields. The design requirements and the architecture of the system are described. Some examples of particle traces computed by the system are also shown

Meaningful scientific visualizations benefit the interpretation of scientific data, concepts and processes. To ensure meaningful visualizations, the visualization system needs to adapt to desires, disabilities and abilities of the user, interpretation aim, resources (hardware, software) available, and the form and content of the data to be visualized. We suggest describing these characteristics with four models: user model, problem domain/task model, resource model and data model. The paper makes suggestions for the generation of a user model as a basis for an adaptive visualization system. We propose to extract information about the user by involving the user in interactive computer tests and games. Relevant abilities tested are color perception, color memory, color ranking, mental rotation, and fine motor coordination

A discussion is given on the validation, verification and evaluation of scientific visualization software. A “bug” usually refers to software doing something different than the programmer intended. Comprehensive testing, especially for software intended for use in innovative environments, is hard. Descriptions and summaries of the tests we have done are often not available to the users. A different source of visualization errors is software that does something different than what the scientist thinks it does. The particular methods used to compute values in the process of creating visualizations are important to the scientists, but vendors are understandably reluctant to reveal all the internals of their products. Is there a workable compromise? Another vulnerability of visualization users is in the choice of a technique which is less effective than others equally available. Visualization researchers and developers should give users the information required to make good decisions about competing visualization techniques. What information is needed? What will it take to gather and distribute it? How should it be tied to visualization software?

We describe the theoretical and practical visualization issues solved in the implementation of an interactive real-time four-dimensional geometry interface for the CAVE, an immersive virtual reality environment. While our specific task is to produce a “virtual geometry” experience by approximating physically correct rendering of manifolds embedded in four dimensions, the general principles exploited by our approach reflect requirements common to many immersive virtual reality applications, especially those involving volume rendering. Among the issues we address are the classification of rendering tasks, the specialized hardware support required to attain interactivity, specific techniques required to render 4D objects, and interactive methods appropriate for our 4D virtual world application

In this paper we show how SAVS, a tool for visualization and data analysis in space and atmospheric science, can be used to quickly and easily address problems that would previously have been far more laborious to solve. Based on the popular AVS package, SAVS presents the user with an environment tailored specifically for the physical scientist. Thus there is minimal “startup” time, and the scientist can immediately concentrate on his science problem. The SAVS concept readily generalizes to many other fields of science and engineering

Addresses the needs and requirements of integrating visualization and geographic information system technologies. There are three levels of integration methods: rudimentary, operational and functional. The rudimentary approach uses the minimum amount of data sharing and exchange between these two technologies. The operational level attempts to provide consistency of the data while removing redundancies between the two technologies. The functional form attempts to provide transparent communication between these respective software environments. At this level, the user only needs to request information and the integrated system retrieves or generates the information depending upon the request. This paper examines the role and impact of these three levels of integration. Stepping further into the future, the paper also questions the long-term survival of these separate disciplines

Discusses and debates the role played by 3D visualization in medicine as a set of methods and techniques for displaying 3D spatial information related to the anatomy and the physiology of the human body

3D ultrasound is one of the most interesting non-invasive, non-radiative tomographic techniques. Rendering 3D models from such data is not straightforward due to the noisy, fuzzy nature of ultrasound imaging containing a lot of artefacts. We first apply speckle, median and gaussian prefiltering to improve the image quality. Using several semi-automatic segmentation tools we isolate interesting features within a few minutes. Our improved surface-extraction procedure enables volume rendering of high quality within a few seconds on a normal workstation, thus making the complete system suitable for routine clinical applications

Visualization techniques are applied to an electric power system transmission network to create a graphical picture of network power flows and voltages. A geographic data map is used. Apparent power flow is encoded as the width of an arrow, with direction from real power flow. Flows are superposed on flow limits. Contour plots and color coding failed for representing bus voltages. A two-color thermometer encoding worked well. The resulting visualization is a significant improvement over current user interface practice in the power industry

Environmental issues such as global warming are an active area of international research and concern today. This case study describes various visualization paradigms that have been developed and applied in an attempt to elucidate the information provided by environmental models and observations. The ultimate goal is to accurately measure the existence of any long term climatological change. The global ocean is the starting point, since it is a major source and sink of heat within our global environment

Ash clouds resulting from volcanic eruptions are a serious hazard to aviation safety. In Alaska alone, there are over 40 active volcanoes whose eruptions may affect more than 40,000 flights using the great circle polar routes each year. The clouds are especially problematic because they are invisible to radar and nearly impossible to distinguish from weather clouds. The Arctic Region Supercomputing Center and the Alaska Volcano Observatory have collaborated to develop a system for predicting and visualizing the movement of volcanic ash clouds when an eruption occurs. The output from the model is combined with a digital elevation model to produce a realistic view of the ash cloud which may be examined interactively from any desired point of view at any time during the prediction period. This paper describes the visualization techniques employed in the system and includes a video animation of the 1989 Mount Redoubt eruption which caused complete engine failure on a 747 passenger jet

Vector field rendering is difficult in 3D because the vector icons overlap and hide each other. We propose four different techniques for visualizing vector fields only near surfaces. The first uses motion blurred particles in a thickened region around the surface. The second uses a voxel grid to contain integral curves of the vector field. The third uses many antialiased lines through the surface, and the fourth uses hairs sprouting from the surface and then bending in the direction of the vector field. All the methods use the graphics pipeline, allowing real time rotation and interaction, and the first two methods can animate the texture to move in the flow determined by the velocity field

A visualization goal is to simplify the analysis of large-quantity, numerical data by rendering the data as an image that can be intuitively manipulated. The question the article addresses is whether or not virtual reality techniques are the cure-all to the dilemma of visualizing increasing amounts of data. It determines the usefulness of techniques available today and in the near future that will ease the problem of visualizing complex data. In regards to visualization, the article discusses characteristics of virtual reality systems, data in three-dimensional environments, augmented reality, and virtual reality market opportunities

Line integral convolution (LIC), introduced by B. Cabral and C. Leedom (1993), is a powerful technique for imaging and animating vector fields. We extend the LIC paradigm in three ways: the existing technique is limited to vector fields over a regular Cartesian grid and we extend it to vector fields over parametric surfaces, specifically those found in curvilinear grids, used in computational fluid dynamics simulations; periodic motion filters can be used to animate the flow visualization, but when the flow lies on a parametric surface, the motion appears misleading, and we explain why this problem arises and show how to adjust the LIC algorithm to handle it; we introduce a technique to visualize vector magnitude as well as vector direction, which is based on varying the frequency of the filter function and we develop a different technique based on kernel phase shifts which we have found to show substantially better results. Implementation of these algorithms utilizes texture-mapping hardware to run in real time, which allows them to be included in interactive applications

Flow fields, geodesics, and deformed volumes are natural sources of families of space curves that can be characterized by intrinsic geometric properties such as curvature, torsion, and Frenet frames. By expressing a curve's moving Frenet coordinate frame as an equivalent unit quaternion, we reduce the number of components that must be displayed from nine with six constraints to four with one constraint. We can then assign a color to each curve point by dotting its quaternion frame with a 4D light vector, or we can plot the frame values separately as a curve in the three-sphere. As examples, we examine twisted volumes used in topology to construct knots and tangles, a spherical volume deformation known as the Dirac string trick, and streamlines of 3D vector flow fields

The paper provides a review of the field of multidimensional data visualisation and discusses some promising methodologies. It considers some crucial problems and directions. The emphasis is more on concepts and foundations rather than ad hoc methods. Visualization is considered as a collection of transformations from problem domains to a perceptual domain, usually visual. The paper discusses the extension of visualisation from the pixel to icons