DevLan/vispubs huggingface dataset:
The multilevel finite element method for adaptive mesh optimization and visualization of volume data
Authors: Roberto Grosso, Christoph Lürig, Thomas Ertl
Published at Vis, 1997

Multilevel representations and mesh reduction techniques have been used for accelerating the processing and the rendering of large datasets representing scalar- or vector-valued functions defined on complex 2D or 3D meshes. We present a method based on finite element approximations which combines these two approaches in a new and unique way that is conceptually simple and theoretically sound. The main idea is to consider mesh reduction as an approximation problem in appropriate finite element spaces. Starting with a very coarse triangulation of the functional domain, a hierarchy of highly non-uniform tetrahedral (or triangular in 2D) meshes is generated adaptively by local refinement. This process is driven by controlling the local error of the piecewise linear finite element approximation of the function on each mesh element. A reliable and efficient computation of the global approximation error and a multilevel preconditioned conjugate gradient solver are the key components of the implementation. In order to analyze the properties and advantages of the adaptively generated tetrahedral meshes, we implemented two volume visualization algorithms: an iso-surface extractor and a ray-caster. Both algorithms, while conceptually simple, show significant speedups over conventional methods delivering comparable rendering quality from adaptively compressed datasets.
The VSBUFFER: visibility ordering of unstructured volume primitives by polygon drawing
Authors: Rüdiger Westermann, Thomas Ertl
Published at Vis, 1997

Different techniques have been proposed for rendering volumetric scalar data sets. Usually these approaches are focusing on orthogonal cartesian grids, but in the last years research did also concentrate on arbitrary structured or even unstructured topologies. In particular, direct volume rendering of these data types is numerically complex and mostly requires sorting the whole database. We present a new approach to direct rendering of convex, voluminous polyhedra on arbitrary grid topologies, which efficiently use hardware assisted polygon drawing to support the sorting procedure. The key idea of this technique lies in a two pass rendering approach. First, the volume primitives are drawn in polygon mode to obtain their cross sections in the VSBUFFER orthogonal to the viewing plane. Second, this buffer is traversed in front to back order and the volume integration is performed. Thus, the complexity of the sorting procedure is reduced. Furthermore, any connectivity information can be completely neglected, which allows for the rendering of arbitrary scattered, convex polyhedra.
Towards efficient visualization support for single-block and multi-block datasets
Authors: Jean-Marie Favre
Published at Vis, 1997

Large simulation grids and multi-grid configurations impose many constraints on commercial visualization software. When available RAM is limited and graphics primitives are numbered in millions, alternative techniques for data access and processing are necessary. In this case study, we present our contributions to a visualization environment based on the AVS/Express software. We demonstrate how the efficient visualization of large datasets relies upon several forms of resource sharing, and alternate and efficient data access techniques.
Two-phase perspective ray casting for interactive volume navigation
Authors: Martin L. Brady, Kenneth K. Jung, H. T. Nguyen, Thinh P. Q. Nguyen
Published at Vis, 1997

Volume navigation is the interactive exploration of volume data sets by "flying" the view point through the data, producing a volume rendered view at each frame. The authors present an inexpensive perspective volume navigation method designed to run on a PC platform with accelerated 3D graphics hardware. They compute perspective projections at each frame, allow trilinear interpolation of sample points, and render both gray scale and RGB volumes by volumetric compositing. The implementation handles arbitrarily large volumes, by dynamically swapping data within the local depth-limited frustum into main memory as the viewpoint moves through the volume. They describe a new ray casting algorithm that takes advantage of the coherence inherent in adjacent frames to generate a sequence of approximate animated frames much faster than they could be computed individually. They also take advantage of the 3D graphics acceleration hardware to offload much of the alpha blending and resampling from the CPU.
UFLIC: a line integral convolution algorithm for visualizing unsteady flows
Authors: Han-Wei Shen, David L. Kao
Published at Vis, 1997

The paper presents an algorithm, UFLIC (Unsteady Flow LIC), to visualize vector data in unsteady flow fields. Using line integral convolution (LIC) as the underlying method, a new convolution algorithm is proposed that can effectively trace the flow's global features over time. The new algorithm consists of a time-accurate value depositing scheme and a successive feedforward method. The value depositing scheme accurately models the flow advection, and the successive feedforward method maintains the coherence between animation frames. The new algorithm can produce time-accurate, highly coherent flow animations to highlight global features in unsteady flow fields. CFD scientists, for the first time, are able to visualize unsteady surface flows using the algorithm.
Viewing IGES files through VRML
Authors: Jed Marti
Published at Vis, 1997

This paper describes our experiences with using the Virtual Reality Modeling Language (VRML) to view files in the Initial Graphics Exchange Specification (IGES) format using a Java-based translator from IGES to VRML and HTML (Hypertext Markup Language). The paper examines the conversion problems between IGES and VRML and presents some results of the process.
Virtualized reality: constructing time-varying virtual worlds from real world events
Authors: Peter Rander, P. J. Narayanan, Takeo Kanade
Published at Vis, 1997

Virtualized reality is a modeling technique that constructs full 3D virtual representations of dynamic events from multiple video streams. Image-based stereo is used to compute a range image corresponding to each intensity image in each video stream. Each range and intensity image pair encodes the scene structure and appearance of the scene visible to the camera at that moment, and is therefore called a visible surface model (VSM). A single time instant of the dynamic event can be modeled as a collection of VSMs from different viewpoints, and the full event can be modeled as a sequence of static scenes-the 3D equivalent of video. Alternatively, the collection of VSMs at a single time can be fused into a global 3D surface model, thus creating a traditional virtual representation out of real world events. Global modeling has the added benefit of eliminating the need to hand-edit the range images to correct errors made in stereo, a drawback of previous techniques. Like image-based rendering models, these virtual representations can be used to synthesize nearly any view of the virtualized event. For this reason, the paper includes a detailed comparison of existing view synthesis techniques with the authors' own approach. In the virtualized representations, however, scene structure is explicitly represented and therefore easily manipulated, for example by adding virtual objects to (or removing virtualized objects from) the model without interfering with real event. Virtualized reality, then, is a platform not only for image-based rendering but also for 3D scene manipulation.
Visualization of geometric algorithms in an electronic classroom
Authors: Maria Shneerson, Ayellet Tal
Published at Vis, 1997

This paper investigates the visualization and animation of geometric computing in a distributed electronic classroom. We show how focusing in a well-defined domain makes it possible to develop a compact system that is accessible to even naive users. We present a conceptual model and a system, GASP-II (Geometric Animation System, Princeton, II), that realizes this model in the geometric domain. The system allows the presentation and interactive exploration of 3D geometric algorithms over a network.
Visualization of height field data with physical models and texture photomapping
Authors: Dru Clark, Michael J. Bailey
Published at Vis, 1997

The paper discusses a unique way to visualize height field data-the use of solid fabricated parts with a photomapped texture to display scalar information. In this process, the data in a height field are turned into a 3D solid representation through solid freeform fabrication techniques, in this case laminated object manufacturing. Next, that object is used as a 3D "photographic plate" to allow a texture image representing scalar data to be permanently mapped onto it. The paper discusses this process and how it can be used in different visualization situations.
Visualization of higher order singularities in vector fields
Authors: Gerik Scheuermann, Hans Hagen, Heinz Krüger, Martin Menzel, Alyn P. Rockwood
Published at Vis, 1997

Presents an algorithm for the visualization of vector field topology based on Clifford algebra. It allows the detection of higher-order singularities. This is accomplished by first analysing the possible critical points and then choosing a suitable polynomial approximation, because conventional methods based on piecewise linear or bilinear approximation do not allow higher-order critical points and destroy the topology in such cases. The algorithm is still very fast, because of using linear approximation outside the areas with several critical points.
Visualization of large terrains in resource-limited computing environments
Authors: Boris Rabinovich, Craig Gotsman
Published at Vis, 1997

The authors describe a software system supporting interactive visualization of large terrains in a resource-limited environment, i.e. a low-end client computer accessing a large terrain database server through a low-bandwidth network. By "large", they mean that the size of the terrain database is orders of magnitude larger than the computer RAM. Superior performance is achieved by manipulating both geometric and texture data at a continuum of resolutions, and, at any given moment, using the best resolution dictated by the CPU and bandwidth constraints. The geometry is maintained as a Delaunay triangulation of a dynamic subset of the terrain data points, and the texture compressed by a progressive wavelet scheme. A careful blend of algorithmic techniques enables the system to achieve superior rendering performance on a low-end computer by optimizing the number of polygons and texture pixels sent to the graphics pipeline. It guarantees a frame rate depending only on the size and quality of the rendered image, independent of the viewing parameters and scene database size. An efficient paging scheme minimizes data I/O, thus enabling the use of the system in a low-bandwidth client/server data-streaming scenario, such as on the Internet.
Visualization of plant growth
Authors: Jeremy J. Loomis, Xiuwen Liu, Zhaohua Ding, Kikuo Fujimura, Michael L. Evans, Hideo Ishikawa
Published at Vis, 1997

The measurement, analysis and visualization of plant growth is of primary interest to plant biologists. We are developing software tools to support such investigations. There are two parts in this investigation, namely growth visualization of (i) a plant root and (ii) a plant stem. For both domains, the input data is a stream of images taken by cameras. The tools being developed make it possible to measure various time-varying quantities, such as differential growth. For both domains, the plant is modeled by using flexible templates to represent non-rigid motions.
Visualization of rotation fields
Authors: Mark A. Livingston
Published at Vis, 1997

We define a rotation field by extending the notion of a vector field to rotations. A vector field has a vector as a value at each point of its domain; a rotation field has a rotation as a value at each point of its domain. Rotation fields result from mapping the orientation error of tracking systems. We build upon previous methods for the visualization of vector fields, tensor fields and rotations at a point, to visualize a rotation field resulting from calibration of a commonly-used magnetic tracking system.
Visualizing the behaviour of higher dimensional dynamical systems
Authors: Rainer Wegenkittl, Helwig Löffelmann, M. Eduard Gröller
Published at Vis, 1997

In recent years scientific visualization has been driven by the need to visualize high-dimensional data sets within high-dimensional spaces. However most visualization methods are designed to show only some statistical features of the data set. The paper deals with the visualization of trajectories of high-dimensional dynamical systems which form a L/sub n//sup n/ data set of a smooth n-dimensional flow. Three methods that are based on the idea of parallel coordinates are presented and discussed. Visualizations done with these new methods are shown and an interactive visualization tool for the exploration of high-dimensional dynamical systems is proposed.
VizWiz: a Java applet for interactive 3D scientific visualization on the Web
Authors: Cherilyn Michaels, Michael J. Bailey
Published at Vis, 1997

VizWiz is a Java applet that provides basic interactive scientific visualization functionality, such as isosurfaces, cutting planes, and elevation plots, for 2D and 3D datasets that can be loaded into the applet by the user via, the applet's Web server. VizWiz is unique in that it is a completely platform independent scientific visualization tool, and is usable over the Web, without being manually downloaded or installed. Its 3D graphics are implemented using only the Java AWT API, making them portable across all Java supporting platforms. The paper describes the implementation of VizWiz, including design tradeoffs. Graphics performance figures are provided for a number of different platforms. A solution to the problem of uploading user data files into a Java applet, working around security limitations, is demonstrated. The lessons learned from this project are discussed.
Volume rendering of abdominal aortic aneurysms
Authors: Roger C. Tam, Christopher G. Healey, Borys Flak, Peter Cahoon
Published at Vis, 1997

One well known application area of volume rendering is the reconstruction and visualization of output from medical scanners like computed tomography (CT). 2D greyscale slices produced by these scanners can be reconstructed and displayed onscreen as a 3D model. Volume visualization of medical images must address two important issues. First, it is difficult to segment medical scans into individual materials based only on intensity values. Second, although greyscale images are the normal method for displaying medical volumes, these types of images are not necessarily appropriate for highlighting regions of interest within the volume. Studies of the human visual system have shown that individual intensity values are difficult to detect in a greyscale image. In these situations colour is a more effective visual feature. We addressed both problems during the visualization of CT scans of abdominal aortic aneurysms. We have developed a classification method that empirically segments regions of interest in each of the 2D slices. We use a perceptual colour selection technique to identify each region of interest in both the 2D slices and the 3D reconstructed volumes. The result is a colourized volume that the radiologists are using to rapidly and accurately identify the locations and spatial interactions of different materials from their scans. Our technique is being used in an experimental post operative environment to help to evaluate the results of surgery designed to prevent the rupture of the aneurysm. In the future, we hope to use the technique during the planning of placement of support grafts prior to the actual operation.
Vortex identification-applications in aerodynamics: a case study
Authors: David N. Kenwright, Robert Haimes
Published at Vis, 1997

An eigenvector method for vortex identification has been applied to recent numerical and experimental studies in external flow aerodynamics. It is shown to be an effective way to extract and visualize features such as vortex cores, spiral vortex breakdowns, vortex bursting, and vortex diffusion. Several problems are reported and illustrated. These include: disjointed line segments, detecting non-vortical flow features, and vortex core displacement. Future research and applications are discussed, such as using vortex cores to guide automatic grid refinement.
Wavelet-based multiresolutional representation of computational field simulation datasets
Authors: Zhifan Zhu, Raghu Machiraju, Bryan Fry, Robert J. Moorhead II
Published at Vis, 1997

The paper addresses multiresolutional representation of datasets arising from a computational field simulation. The approach determines the regions of interest, breaks the volume into variable size blocks to localize the information, and then codes each block using a wavelet transform. The blocks are then ranked by visual information content so that the most informative wavelet coefficients can be embedded in a bit stream for progressive transmission or access. The technique is demonstrated on a widely-used computational field simulation dataset.
A spreadsheet approach to information visualization
Authors: Ed H. Chi, Phillip Barry, John Riedl, Joseph A. Konstan
Published at InfoVis, 1997

In information visualization, as the volume and complexity of the data increases, researchers require more powerful visualization tools that enable them to more effectively explore multidimensional datasets. We discuss the general utility of a novel visualization spreadsheet framework. Just as a numerical spreadsheet enables exploration of numbers, a visualization spreadsheet enables exploration of visual forms of information. We show that the spreadsheet approach facilitates certain information visualization tasks that are more difficult using other approaches. Unlike traditional spreadsheets, which store only simple data elements and formulas in each cell, a visualization spreadsheet cell can hold an entire complex data set, selection criteria, viewing specifications, and other information needed for a full-fledged information visualization. Similarly, inter-cell operations are far more complex, stretching beyond simple arithmetic and string operations to encompass a range of domain-specific operators. We have built two prototype systems that illustrate some of these research issues. The underlying approach in our work allows domain experts to define new data types and data operations, and enables visualization experts to incorporate new visualizations, viewing parameters, and view operations.
Adaptive information visualization based on the user's multiple viewpoints - interactive 3D visualization of the WWW
Authors: Teruhiko Teraoka, Minoru Maruyama
Published at InfoVis, 1997

We introduce the adaptive information visualization method for hypermedia and the WWW based on the user's multiple viewpoints. We propose two graphical interfaces, the CVI and the RF-Cone. The CVI is the interface for interactive viewpoint selection. We can select a viewpoint reflecting our interests by using the CVI. According to the given viewpoint, the RF-Cone adaptively organizes the 3D representation of the hypermedia so that we can understand the semantic and structural relationship of the hypermedia and easily retrieve the information. Combining these methods, we have developed the WWW visualization system which can provide highly efficient navigation.
Cacti: a front end for program visualization
Authors: Steven P. Reiss
Published at InfoVis, 1997

We describe a system that allows the user to rapidly construct program visualizations over a variety of data sources. Such a system is a necessary foundation for using visualization as an aid to software understanding. The system supports an arbitrary set of data sources so that information from both static and dynamic analysis can be combined to offer meaningful software visualizations. It provides the user with a visual universal-relation front end that supports the definition of queries over multiple data sources without knowledge of the structure or contents of the sources. It uses a flexible back end with a range of different visualizations, most geared to the efficient display of large amounts of data. The result is a high-quality, easy-to-define program visualization that can address specific problems and hence is useful for software understanding. The overall system is flexible and extensible in that both the underlying data model and the set of visualizations are defined in resource files.
Coordinating declarative queries with a direct manipulation data exploration environment
Authors: Mark Derthick, Steven F. Roth, John Kolojejchick
Published at InfoVis, 1997

Interactive visualization techniques allow data exploration to be a continuous process, rather than a discrete sequence of queries and results as in traditional database systems. However limitations in expressive power of current visualization systems force users to go outside the system and form a new dataset in order to perform certain operations, such as those involving the relationship among multiple objects. Further, there is no support for integrating data from the new dataset into previous visualizations, so users must recreate them. Visage's information centric paradigm provides an architectural hook for linking data across multiple queries, removing this overhead. This paper describes the addition to Visage of a visual query language, called VQE, which allows users to express more complicated queries than in previous interactive visualization systems. Visualizations can be created from queries and vice versa. When either is updated, the other changes to maintain consistency.
Design and evaluation of incremental data structures and algorithms for dynamic query interfaces
Authors: Egemen Tanin, Richard Beigel, Ben Shneiderman
Published at InfoVis, 1997

A dynamic query interface (DQI) is a database access mechanism that provides continuous real-time feedback to the user during query formulation. Previous work shows that DQIs are elegant and powerful interfaces to small databases. Unfortunately, when applied to large databases, previous DQI algorithms slow to a crawl. We present a new incremental approach to DQI algorithms and display updates that work well with large databases, both in theory and in practice.
Domesticating Bead: adapting an information visualization system to a financial institution
Authors: Dominique Brodbeck, Matthew Chalmers, Aran Lunzer, Pamela Cotture
Published at InfoVis, 1997

The Bead visualization system employs a fast algorithm for laying out high-dimensional data in a low-dimensional space, and a number of features added to 3D visualizations to improve imageability. We describe recent work on both aspects of the system, in particular a generalization of the data types laid out and the implementation of imageability features in a 2D visualization tool. The variety of data analyzed in a financial institution such as UBS, and the ubiquity of spreadsheets as a medium for analysis, led us to extend our layout tools to handle data in a generic spreadsheet format. We describe the metrics of similarity used for this data type, and give examples of layouts of sets of records of financial trades. Conservatism and scepticism with regard to 3D visualization, along with the lack of functionality of widely available 3D web browsers, led to the development of a 2D visualization tool with refinements of a number of our imageability features.