DevLan/vispubs huggingface dataset:
Interactive visualization of ocean circulation models
Authors: Scott Nations, Robert J. Moorhead II, Kelly P. Gaither, Steve Aukstakalnis, Rhonda Vickery, Warren Carl Couvillion Jr., Daniel N. Fox, Peter Flynn, Alan J. Wallcraft, Patrick Hogan, Ole Martin Smedstad
Published at Vis, 1996

Visualization of computational oceanography is traditionally a post-processing step. This batch orientation is clumsy if one wants to observe the effect of a wide range of parameters on the solution. This paper describes the conversion of an ocean circulation model from this traditional design to an interactive program in which the computed solution is viewed in real-time over a wide-area network and the user is given the ability to change the model parameters and immediately observe the impact this has on the solution.
Isosurfacing in span space with utmost efficiency (ISSUE)
Authors: Han-Wei Shen, Charles D. Hansen, Yarden Livnat, Christopher R. Johnson 0001
Published at Vis, 1996

We present efficient sequential and parallel algorithms for isosurface extraction. Based on the Span Space data representation, new data subdivision and searching methods are described. We also present a parallel implementation with an emphasis on load balancing. The performance of our sequential algorithm to locate the cell elements intersected by isosurfaces is faster than the Kd tree searching method originally used for the Span Space algorithm. The parallel algorithm can achieve high load balancing for massively parallel machines with distributed memory architectures.
LISTEN: sounding uncertainty visualization
Authors: Suresh K. Lodha, Catherine M. Wilson, Robert E. Sheehan
Published at Vis, 1996

Integrated presentation of data with uncertainty is a worthy goal in scientific visualization. It allows researchers to make informed decisions based on imperfect data. It also allows users to visually compare and contrast different algorithms for performing the same task or different models for representing the same physical phenomenon. We present LISTEN-a data sonification system that has been incorporated into two visualization systems: a system for visualizing geometric uncertainty of surface interpolants; and a system for visualizing uncertainty in fluid flow. LISTEN is written in C++ for the SGI platform. It works with the SGI internal audio chip or a MIDI device or both. LISTEN is an object-oriented system that is modular, flexible, adaptable, portable, interactive and extensible. We demonstrate that sonification is very effective as an additional tool in visualizing geometric and fluid flow uncertainty.
Mathematical Vkualization: Standing at the Crossroads
Authors: Tamara Munzner, David Banks, George Francis, Andrew J. Hanson, Loki Jörgenson
Published at Vis, 1996

Proponents of computer-aided mathematical visualization argue that visualization can help build the intuition necessary to both propose theorems and understand and create proofs. Critics counter that the traditional pristine edifice of theorem-proof mathematics is in danger of being undermined by a dangerous lack of rigor. The acceptance, or lack thereof, of visualization as a legitimate part of mathematical inquiry has implications not only for mathematicians, but for entire visualization community. Among the questions this panel will address are:
Mesh reduction with error control
Authors: Reinhard Klein, Gunther Liebich, Wolfgang Straßer
Published at Vis, 1996

In many cases the surfaces of geometric models consist of a large number of triangles. Several algorithms were developed to reduce the number of triangles required to approximate such objects. Algorithms that measure the deviation between the approximated object and the original object are only available for special cases. We use the Hausdorff distance between the original and the simplified mesh as a geometrically meaningful error value which can be applied to arbitrary triangle meshes. We present a new algorithm to reduce the number of triangles of a mesh without exceeding a user defined Hausdorff distance between the original and simplified mesh. As this distance is parameterization independent, its use as error measure is superior to the use of the L/sup /spl infin//-Norm between parameterized surfaces. Furthermore the Hausdorff distance is always less than the distance induced by the L/sup /spl infin//-Norm. This results in higher reduction rates. Excellent results were achieved by the new decimation algorithm for triangle meshes that has been used in different application areas such as volume rendering, terrain modeling and the approximations of parameterized surfaces. The key advantages of the new algorithm are: it guarantees a user defined position dependent approximation error; it allows one to generate a hierarchical geometric representation in a canonical way; it automatically preserves sharp edges.
Multi-frequency noise for LIC
Authors: Ming-Hoe Kiu, David C. Banks
Published at Vis, 1996

We present a way to visualize a flow field using Line Integral Convolution (LIC) with a multi frequency noise texture. A broad range of feature sizes can enhance a user's perception of the magnitudes and direction of the flow. In addition, the multiple scales of feature size help a user clarify the motion of the flow in an animation.
Multiresolution multidimensional wavelet brushing
Authors: Pak Chung Wong, R. Daniel Bergeron
Published at Vis, 1996

Brushing is a data visualization technique that identifies and highlights data subsets. We introduce a form of brushing in which the brushed data is usually displayed at a different resolution than the non brushed data. The paper presents the rationale behind the multiresolution support of multivariate data visualization and describes the construction of multiresolution brushing using wavelet approximations. The idea is implemented in an enhanced version of XmdvTool. Real scientific data is used for demonstration and practical applications are suggested.
Octree-based decimation of marching cubes surfaces
Authors: Raj Shekhar, Elias Fayyad, Roni Yagel, J. Fredrick Cornhill
Published at Vis, 1996

The marching cubes (MC) algorithm is a method for generating isosurfaces. It also generates an excessively large number of triangles to represent an isosurface; this increases the rendering time. This paper presents a decimation method to reduce the number of triangles generated. Decimation is carried out before creating a large number of triangles. Four major steps comprise the algorithm: surface tracking, merging, crack patching and triangulation. Surface tracking is an enhanced implementation of the MC algorithm. Starting from a seed point, the surface tracker visits only those cells likely to compose part of the desired isosurface. The cells making up the extracted surface are stored in an octree that is further processed. A bottom-up approach is taken in merging the cells containing a relatively flat approximating surface. The finer surface details are maintained. Cells are merged as long as the error due to such an operation is within a user-specified error parameter, or a cell acquires more than one connected surface component in it. A crack patching method is described that forces edges of smaller cells to lie along those of the larger neighboring cells. The overall saving in the number of triangles depends both on the specified error value and the nature of the data. Use of the hierarchical octree data structure also presents the potential of incremental representation of surfaces. We can generate a highly smoothed surface representation which can be progressively refined as the user-specified error value is decreased.
Opacity-modulating triangular textures for irregular surfaces
Authors: Penny Rheingans
Published at Vis, 1996

Many scientific and medical visualization techniques produce irregular surfaces whose shape and structure need to be understood. Examples include tissue and tumor boundaries in medical imaging, molecular surfaces and force thresholds in chemical and pharmaceutical applications, and isosurfaces in a wide range of 3D domains. The 3D shape of such surfaces can be particularly difficult to interpret because of the unfamiliar, irregular shapes, the potential concavities and bulges, and the lack of parallel lines and right angles to provide perspective depth cues. Attempts to display multiple irregular surfaces by making some or all of them transparent further complicates the problem. Texture can provide valuable cues to aid in the interpretation of irregular surfaces. Opacity-modulating textures offer a mechanism for the display of multiple surfaces without the extreme loss of clarity of multiple transparent surfaces. This paper presents a method for creating simple repeating textures and mapping them onto irregular surfaces.
Optimizing triangle strips for fast rendering
Authors: Francine Evans, Steven Skiena, Amitabh Varshney
Published at Vis, 1996

Almost all scientific visualization involving surfaces is currently done via triangles. The speed at which such triangulated surfaces can be displayed is crucial to interactive visualization and is bounded by the rate at which triangulated data can be sent to the graphics subsystem for rendering. Partitioning polygonal models into triangle strips can significantly reduce rendering times over transmitting each triangle individually. We present new and efficient algorithms for constructing triangle strips from partially triangulated models, and experimental results showing these strips are on average 15% better than those from previous codes. Further, we study the impact of larger buffer sizes and various queuing disciplines on the effectiveness of triangle strips.
Perceptualisation using a tactile mouse
Authors: Robert G. Hughes, A. Robin Forrest
Published at Vis, 1996

Whilst there has been considerable effort in constructing force feedback devices for use in virtual environments, and in the use of touch as a prosthesis for the blind, there has been little work on the use of touch in the visualisation or more properly, perceptualisation of data. Touch potentially offers an additional dimension of perception where visualisation is limited by screen size, resolution, and visual overload. We describe some tactile mice and experiments in using tactile mice for a variety of perceptualisation tasks.
Raycasting vector fields
Authors: Thomas Frühauf
Published at Vis, 1996

Direct Volume Rendering (DVR) allows the holistic visualization of huge volumetric data sets in a single image. Computational fluid dynamics data is in principle well suited for DVR. But efficient mappings of the directional information of vector fields are still to be found. We investigate how the raycasting technique can be used to directly render vector fields. Our approach is based on the perception that other flow visualization techniques use visualization objects that are locally tangential to the vector field together with directed light sources. From this, we developed the idea to shade streamlines at sampling points when raycasting a vector field. We extended this approach further to more abstract mappings where pseudo color is used. Combining opacity mapping, pseudo color mapping, and streamline shading we can express flow speed and flow direction together in one single image.
Real-time incremental visualization of dynamic ultrasound volumes using parallel BSP trees
Authors: William F. Garrett, Henry Fuchs, Mary C. Whitton, Andrei State
Published at Vis, 1996

We present a method for producing real-time volume visualizations of continuously captured, arbitrarily-oriented 2D arrays (slices) of data. Our system constructs a 3D representation on-the-fly from incoming 2D ultrasound slices by modeling and rendering the slices as planar polygons with translucent surface textures. We use binary space partition (BSP) tree data structures to provide non-intersecting, visibility-ordered primitives for accurate opacity accumulation images. New in our system is a method of using parallel, time-shifted BSP trees to efficiently manage the continuously captured ultrasound data and to decrease the variability in image generation time between output frames. This technique is employed in a functioning real-time augmented reality system that a physician has used to examine human patients prior to breast biopsy procedures. We expect the technique can be used for real-time visualization of any 2D data being collected from a tracked sensor moving along an arbitrary path.
Real-time slicing of data space
Authors: Roger Crawfis
Published at Vis, 1996

Real time rendering of iso contour surfaces is problematic for large complex data sets. An algorithm is presented that allows very rapid representation of an interval set surrounding an iso contour surface. The algorithm draws upon three main ideas. A fast indexing scheme is used to select only those data points near the contour surface. Hardware assisted splatting is then employed on these data points to produce a volume rendering of the interval set. Finally, by shifting a small window through the indexing scheme or data space, animated volumes are produced showing the changing contour values. In addition to allowing fast selection and rendering of the data, the indexing scheme allows a much compressed representation of the data by eliminating "noise" data points.
Results in mathematics and music: Visualization of roughness in musical consonance
Authors: Florian Sobieczky
Published at Vis, 1996

The definition of consonance as the ability to resolve a sound into the pitch categories is introduced. For a vector space of chords a norm is used to evaluate the consonance linearly in dependence of the instrument used. It is shown that in the corresponding Hilbert space the chords which usually appear together in a conventional musical piece are recognized in terms of "closeness".
Surface Rendering Versus Volume Rendering In Medical Imaging: Techniques And Applications
Authors: Ramin Shahidi, William E. Lorensen, Ron Kikinis, John Flynn, Arie E. Kaufman, Sandy Napel
Published at Vis, 1996

High resolution imaging modalities. combined with advances in computer technology has prompted renewed interest and led to significant progress in volumetric reconstruction of medical images. Clinical assessment of this technique and whether it can provide enhanced diagnostic interpretation is currently under investigation by various medical and scientific groups. The purpose of this panel is to evaluate the clinical utility of two major 3D rendering techniques that allow the user to “fly through” and around medical data-sets.
Temporal continuity of levels of detail in Delaunay triangulated terrain
Authors: Daniel Cohen-Or, Yishay Levanoni
Published at Vis, 1996

The representation of a scene at different levels of detail is necessary to achieve real-time rendering. In aerial views, only the part of the scene that is close to the viewing point needs to be displayed with a high level of detail, while more distant parts can be displayed with a low level of detail. However, when a sequence of images is generated and displayed in real-time, the transition between different levels of detail causes noticeable temporal aliasing. In this paper, we propose a method, based on object blending, that visually softens the transition between two levels of Delaunay triangulation. We present an algorithm that establishes, in an off-line process, a correspondence between two given polygonal objects. The correspondence enables on-line blending between two representations of an object, so that one representation (level of detail) progressively evolves into the other.
The challenges of visualizing and modeling environmental data
Authors: Yingcai Xiao, John P. Ziebarth, Chuck Woodbury, Eric Bayer, Bruce Rundell, Jeroen van der Zijp
Published at Vis, 1996

Existing volume visualization techniques are typically applied to a three-dimensional grid. This presents some challenging problems in the visualization of environmental data. This data often consists of unevenly distributed samples. Typically a two-step approach is used to visualize environmental data. First the unevenly distributed sample data are modeled onto a uniform 3-D grid. This grid model is subsequently rendered using conventional grid-based visualization techniques. This paper discusses some of the limitations of this approach and highlights areas where further research is needed to improve the accuracy of visualization for environmental applications.
The Design and Implementation of an Object-Oriented Toolkit for 3D Graphics and Visualization
Authors: William J. Schroeder, Ken Martin, William E. Lorensen
Published at Vis, 1996

The Visualization Toolkit (vtk) is a freely available C++ class library for 3D graphics and visualization. We describe core characteristics of the toolkit. This includes a description of object oriented models for graphics and visualization; methods for synchronizing system execution; a summary of data representation schemes; the role of C++; issues in portability across PC and Unix systems; and how we automatically wrap the C++ class library with interpreted languages such as Java and Tcl. We also demonstrate the capabilities of the system for scalar, vector, tensor, and other visualization techniques.
Three Dimensional Visualization of Proteins in Cellular Interactions
Authors: Colin R. F. Monks, Patricia Crossno, George S. Davidson, Constantine J. Pavlakos, Abraham Kupfer, Cláudio T. Silva, Brian N. Wylie
Published at Vis, 1996

In researching the communication mechanisms between cells of the immune system, visualization of proteins in three dimensions can be used to determine which proteins are capable of interacting with one another at a given time by showing their spatial colocality. Volume data sets are created using digital confocal immunofluorescence microscopy. A variety of visualization approaches are then used to examine the interactions. These include volume rendering, isosurface extraction, and virtual reality. Based on our experiences, we have concluded that no single one of these approaches provides a complete solution for visualizing biological data. However, in combination, their respective strengths complement one another to provide an understanding of the data.
Time management, simultaneity and time-critical computation in interactive unsteady visualization environments
Authors: Steve Bryson, Sandy Johan
Published at Vis, 1996

The paper describes time management and time critical computing for a near real time interactive unsteady visualization environment. Subtle issues regarding the flow of time are described, formalized and addressed. The resulting system correctly reflects time behavior while allowing the user to control the flow of time. The problem of time critical computation is discussed and a solution is presented. These time critical algorithms provide control over the frame rate of a visualization system, allowing interactive exploration.
Triangular NURBS surface modeling of scattered data
Authors: Song Han, Gérard G. Medioni
Published at Vis, 1996

We propose to fit triangular NURBS surfaces to noisy, sparse, scattered 3D data while simultaneously localizing and preserving sharp edges. We use a vector voting method to interpolate, from sparse data, three dense potential fields for surfaces, edges, and junctions. The global voting interpolants encode several human perceptual grouping principles such as cosurfacity, proximity, and constancy of curvature. The inferred potential fields are stored in three volumetric grids, giving each voxel the probability of being a surface point, an edge point, and a junction point. Then we use a new model called "winged B snakes", which are deformable triangular NURBS surfaces embedded with active curves, to fit the surfaces and align the edges and junctions. Finally, a smooth C/sup 1/ surface which preserves discontinuity edges and junctions is constructed. Fine tuning and surface fairing is done by adjusting the weights.
Two-handed interactive stereoscopic visualization
Authors: David S. Ebert, Chris Shaw 0002, Amen Zwa, Cindy Starr
Published at Vis, 1996

This paper describes a minimally immersive interactive system for visualization of multivariate volumetric data. The system, SFA, uses glyph-based volume rendering which does not suffer the initial costs of isosurface rendering or voxel-based volume rendering, while offering the capability of viewing the entire volume. Glyph rendering also allows the simultaneous display of multiple data values per volume location. Two-handed interaction using three-space magnetic trackers and stereoscopic viewing are combined to produce a minimally immersive volumetric visualization system that enhances the user's three-dimensional perception of the data. We describe the usefulness of this system for visualizing volumetric scalar and vector data. SFA allows the three-dimensional volumetric visualization, manipulation, navigation, and analysis of multivariate, time-varying volumetric data, increasing the quantity and clarity of the information conveyed from the visualization system.
UFLOW: visualizing uncertainty in fluid flow
Authors: Suresh K. Lodha, Alex T. Pang, Robert E. Sheehan, Craig M. Wittenbrink
Published at Vis, 1996

Uncertainty or errors are introduced in fluid flow data as the data is acquired, transformed and rendered. Although researchers are aware of these uncertainties, little has been done to incorporate them in the existing visualization systems for fluid flow. In the absence of integrated presentation of data and its associated uncertainty, the analysis of the visualization is incomplete at best and may lead to inaccurate or incorrect conclusions. The article presents UFLOW-a system for visualizing uncertainty in fluid flow. Although there are several sources of uncertainties in fluid flow data, in this work, we focus on uncertainty arising from the use of different numerical algorithms for computing particle traces in a fluid flow. The techniques that we have employed to visualize uncertainty in fluid flow include uncertainty glyphs, flow envelopes, animations, priority sequences, twirling batons of trace viewpoints, and rakes. These techniques are effective in making the users aware of the effects of different integration methods and their sensitivity, especially near critical points in the flow field.
Untangling Knots by Stochastic Energy Optimization
Authors: Milana Huang, Robert P. Grzeszczuk, Louis H. Kauffman
Published at Vis, 1996

A method for visualizing unknottedness of mathematical knots via energy optimization with simulated annealing is presented. In this method a potential field is formed around a tangled rope that causes it to self-repel. By allowing the rope to evolve in this field in search of an energy minimizing configuration we can determine the knot type of the initial configuration. In particular, it is natural to conjecture that if such a "charged rope" was not initially knotted, it will reach its minimal potential in a circular configuration, given a suitable energy functional. Because situations potentially arise in which the functional may not be strictly unimodal, we suggest it to be advantageous to use a robust stochastic optimization technique (simulated annealing), rather than a deterministic hill climber common in physically based approaches, to make sure that the evolving rope does not settle in a suboptimal configuration. The same method is applicable to simplifying arbitrary knots and links and for establishing knot equivalence. Aside from its theoretical appeal, the method promises to solve practical problems common in genetic research and polymer design.