DevLan/vispubs huggingface dataset:
Interpolation of triangle hierarchies
Authors: Axel Friedrich, Konrad Polthier, Markus Schmies
Published at Vis, 1998

We consider interpolation between keyframe hierarchies. We impose a set of weak constraints that allows smooth interpolation between two keyframe hierarchies in an animation or, more generally, allows the interpolation in an n-parameter family of hierarchies. We use hierarchical triangulations obtained by the Rivara element bisection algorithm (M. Rivara, 1984) and impose a weak compatibility constraint on the set of root elements of all keyframe hierarchies. We show that the introduced constraints are rather weak. The strength of our approach is that the interpolation works in the class of conforming triangulations and simplifies the task of finding the intermediate hierarchy, which is the union of the two (or more) keyframe hierarchies involved in the interpolation process. This allows for an efficient generation of the intermediate connectivity and additionally ensures that the intermediate hierarchy is again a conforming hierarchy satisfying the same constraints.
Isosurface extraction in time-varying fields using a temporal hierarchical index tree
Authors: Han-Wei Shen
Published at Vis, 1998

Many high-performance isosurface extraction algorithms have been proposed in the past several years as a result of intensive research efforts. When applying these algorithms to large-scale time-varying fields, the storage overhead incurred from storing the search index often becomes overwhelming. This paper proposes an algorithm for locating isosurface cells in time-varying fields. We devise a new data structure, called the temporal hierarchical index tree, which utilizes the temporal coherence that exists in a time-varying field and adaptively coalesces the cells' extreme values over time; the resulting extreme values are then used to create the isosurface cell search index. For a typical time-varying scalar data set, not only does this temporal hierarchical index tree require much less storage space, but also the amount of I/O required to access the indices from the disk at different time steps is substantially reduced. We illustrate the utility and speed of our algorithm with data from several large-scale time-varying CFD simulations. Our algorithm can achieve more than 80% of disk-space savings when compared with the existing techniques, while the isosurface extraction time is nearly optimal.
Key Problems and Thorny Issues in Multidimensional Visualization
Authors: Georges G. Grinstein, Sharon J. Laskowski, Alfred Inselberg
Published at Vis, 1998

Starting from early successes of visualization, like Dr. J. Snow’s dot map in 1854 showing the connection of cholera to a water pump, visualization has grown to a powerful principal as well as supportive tool for data discovery. The 1992 IEEE Visualization Conference’s Grand Challenge Panel identified fundamental problems for visualization. This panel will review the 1992 statements and will offer its view of the key problems and issues facing multidimensional visualization today.
Large scale terrain visualization using the restricted quadtree triangulation
Authors: Renato Pajarola
Published at Vis, 1998

Real-time rendering of triangulated surfaces has attracted growing interest in the last few years. However, interactive visualization of very large scale grid digital elevation models is still difficult. The graphics load must be controlled by adaptive surface triangulation and by taking advantage of different levels of detail. Furthermore, management of the visible scene requires efficient access to the terrain database. We describe an all-in-one visualization system which integrates adaptive triangulation, dynamic scene management and spatial data handling. The triangulation model is based on the restricted quadtree triangulation. Furthermore, we present new algorithms of restricted quadtree triangulation. These include among others exact error approximation, progressive meshing, performance enhancements and spatial access.
Level of detail visualization of scalar data sets on irregular surface meshes
Authors: Georges-Pierre Bonneau, Alexandre Gerussi
Published at Vis, 1998

In this article, we build a multi-resolution framework intended to be used for the visualization of continuous piecewise linear functions defined over triangular planar or spherical meshes. In particular, the data set can be viewed at different level of detail, that's to say as a piecewise linear function defined over any simplification of the base mesh. In his multi-resolution form, the function requires strictly the same volume of data than the original input: It is then possible to go through consecutive levels by the use of so-called detail coefficients, with exact reconstruction if desired. We also show how to choose a decimation sequence that leads to a good compromise between the resulting approximation error and the number of removed vertices. The theoretical tools used here are inspired from wavelet-based techniques and extended in the sense that they can handle non-nested approximation spaces.
Multi-Source Data Analysis Challenges
Authors: Samuel P. Uselton, Lloyd Treinish, James P. Ahrens, E. Wes Bethel, Andrei State
Published at Vis, 1998

Author(s): Uselton, S; Ahrens, J; Bethel, W; Treinish, L; State, A | Abstract: The factors making multi-source data analysis pervasive in the near future are: ease and cost effectiveness of digital data acquisition; fidelity, detail and practicality of computational simulations; and networks that make data from many sources accessible to a single user or application. Bringing data from multiple sources together is much more powerful than using each source separately, and computer systems can provide support for users in situations where they would be overwhelmed by volume or complexity without the support. However, multi-source data analysis still face challenges in the Accelerated Strategic Computing Initiative, geosciences, atmospheric sciences, medicine, and aerospace engineering design, and these challenges are presented.
Pixel masks for screen-door transparency
Authors: Jurriaan D. Mulder, Frans C. A. Groen, Jarke J. van Wijk
Published at Vis, 1998

Rendering objects transparently gives additional insight in complex and overlapping structures. However, traditional techniques for the rendering of transparent objects such as alpha blending are not very well suited for the rendering of multiple transparent objects in dynamic scenes. Screen door transparency is a technique to render transparent objects in a simple and efficient way: no sorting is required and intersecting polygons can be handled without further preprocessing. With this technique, polygons are rendered through a mask: only where the mask is present, pixels are set. However, artifacts such as incorrect opacities and distracting patterns can easily occur if the masks are not carefully designed. The requirements on the masks are considered. Next, three algorithms are presented for the generation of pixel masks. One algorithm is designed for the creation of small (e.g. 4/spl times/4) masks. The other two algorithms can be used for the creation of larger masks (e.g. 32/spl times/32). For each of these algorithms, results are presented and discussed.
POPTEX: Interactive ocean model visualization using texture mapping hardware
Authors: Allen McPherson, Mathew Maltrud
Published at Vis, 1998

Global circulation models are used to gain an understanding of the processes that affect the Earth's climate and may ultimately be used to assess the impact of humanity's activities on it. The POP ocean model developed at Los Alamos is an example of such a global circulation model that is being used to investigate the role of the ocean in the climate system. Data output from POP has traditionally been visualized using video technology which precludes rapid modification of visualization parameters and techniques. This paper describes a visualization system that leverages high speed graphics hardware, specifically texture mapping hardware, to accelerate data exploration to interactive rates. We describe the design of the system, the specific hardware features used, and provide examples of its use. The system is capable of viewing ocean circulation simulation results at up to 60 frames per second while loading texture memory at approximately 72 million texels per second.
Production visualization for the ASCI One TeraFLOPS machine
Authors: Philip D. Heermann
Published at Vis, 1998

The delivery of the first one tera-operations/sec computer has significantly impacted production data visualization, affecting data transfer, post processing, and rendering. Terascale computing has motivated a need to consider the entire data visualization system; improving a single algorithm is not sufficient. This paper presents a systems approach to decrease by a factor of four the time required to prepare large data sets for visualization. For daily production use, all stages in the processing pipeline from physics simulation code to pixels on a screen, must be balanced to yield good overall performance. Performance of the initial visualization system is compared with recent improvements. "Lessons learned" from the coordinated deployment of improved algorithms also are discussed, including the need for 64 bit addressing and a fully parallel data visualization pipeline.
Progressive tetrahedralizations
Authors: Oliver G. Staadt, Markus H. Gross
Published at Vis, 1998

The paper describes some fundamental issues for robust implementations of progressively refined tetrahedralizations generated through sequences of edge collapses. We address the definition of appropriate cost functions and explain on various tests which are necessary to preserve the consistency of the mesh when collapsing edges. Although considered a special case of progressive simplicial complexes (J. Popovic and H. Hoppe, 1997), the results of our method are of high practical importance and can be used in many different applications, such as finite element meshing, scattered data interpolation, or rendering of unstructured volume data.
Real-time techniques for 3D flow visualization
Authors: Anton L. Fuhrmann, M. Eduard Gröller
Published at Vis, 1998

Visualization of three-dimensional steady flow has to overcome a lot of problems to be effective. Among them are occlusion of distant details, lack of directional and depth hints and occlusion. We present methods which address these problems for real-time graphic representations applicable in virtual environments. We use dashtubes, i.e., animated, opacity-mapped streamlines, as a visualization icon for 3D-flow visualization. We present a texture mapping technique to keep the level of texture detail along a streamline nearly constant even when the velocity of the flow varies considerably. An algorithm is described which distributes the dashtubes evenly in space. We apply magic lenses and magic boxes as interaction techniques for investigating densely filled areas without overwhelming the observer with visual detail. Implementation details of these methods and their integration in our virtual environment conclude the paper.
Rear-projecting virtual data onto physical terrain: an exercise in two senses being better than one
Authors: Dru Clark, Richard Marciano, Rosemarie McKeon, Michael J. Bailey
Published at Vis, 1998

This paper describes a project that combined physical model fabrication and virtual computer-based data display to create a unique visualization presentation. USGS terrain information on Prince of Wales Island, Alaska was used to create a physical prototype in SDSC's TeleManufacturing Facility. This model was then used as a mold to create a translucent plate of the terrain. Finally, deforestation data from the island was color mapped and rear-projected onto the translucent plate within a light box. The result is a very compelling display in which both the senses of sight and touch are used to make relationships between terrain features and the data more readily apparent.
Scientific visualization and data modeling of scattered sediment contaminant data in New York/New Jersey estuaries
Authors: Hong Ma, Keith W. Jones, Eric A. Stern
Published at Vis, 1998

Sediments in many parts of the New York and New Jersey estuary system are contaminated with toxic organic and inorganic compounds by different sources. Because of the potential environmental consequences, detailed information on the spatial distribution of sediment contaminants is essential in order to carry out routine shipping channel dredging in an environmentally responsible way, and to remediate hot spots cost-effectively and safely. Scientific visualization and scatter data modeling techniques have been successfully applied in analyzing the sparse sampling data of sediment contaminants in New York and New Jersey estuaries, the underlying spatial characteristics of which are otherwise difficult to comprehend. Continuous realizations of contaminant concentrations in the region were obtained by using a spectral domain-decomposition scattered data model and IBM Data Explorer which is a software package for scientific data visualization.
Seabed visualization
Authors: Paul Chapman, Peter Stevens, Derek Wills, Graham R. Brookes
Published at Vis, 1998

The development of a high speed multi-frequency continuous scan sonar at Sonar Research &amp; Development Ltd has resulted in the acquisition of extremely accurate, high resolution bathymetric data. This rich underwater data provides new challenges and possibilities within the field of seabed visualization. This paper introduces the reader to seabed visualization by describing two example case studies which use the Seabed Visualization System developed at SRD. Both case studies, harbour wall and shipwreck visualization, are implemented using real survey data. The high resolution of the data obtained means slight changes in the seabed topography are easily distinguishable. Annual survey inspections in both case studies enable comparisons to be made between the data sets making the visualization system an important tool for management and planning.
Selective visualization of vortices in hydrodynamic flows
Authors: I. Ari Sadarjoen, Frits H. Post, Bing Ma, David C. Banks, Hans-Georg Pagendarm
Published at Vis, 1998

Vortices are important features in many research and engineering fields. Visualization is an important step in gaining more understanding and control of vortices. Vortex detection criteria fall into two categories: point based scalar quantities, calculated at single points, and curve based geometric criteria, calculated for, e.g., streamlines. The first category is easy to compute, but does not work in all cases. The second category is more intuitive and should work in all cases, but currently only works in 2D (or 3D projected) flows. We show applications of both approaches in hydrodynamic flows.
Simplification of tetrahedral meshes
Authors: Issac J. Trotts, Bernd Hamann, Kenneth I. Joy, David F. Wiley
Published at Vis, 1998

We present a method for the construction of multiple levels of tetrahedral meshes approximating a trivariate function at different levels of detail. Starting with an initial, high-resolution triangulation of a three-dimensional region, we construct coarser representation levels by collapsing tetrahedra. Each triangulation defines a linear spline function, where the function values associated with the vertices are the spline coefficients. Based on predicted errors, we collapse tetrahedron in the grid that do not cause the maximum error to exceed a use-specified threshold. Bounds are stored for individual tetrahedra and are updated as the mesh is simplified. We continue the simplification process until a certain error is reached. The result is a hierarchical data description suited for the efficient visualization of large data sets at varying levels of detail.
Simplifying surfaces with color and texture using quadric error metrics
Authors: Michael Garland, Paul S. Heckbert
Published at Vis, 1998

There are a variety of application areas in which there is a need for simplifying complex polygonal surface models. These models often have material properties such as colors, textures, and surface normals. Our surface simplification algorithm, based on iterative edge contraction and quadric error metrics, can rapidly produce high quality approximations of such models. We present a natural extension of our original error metric that can account for a wide range of vertex attributes.
Size preserving pattern mapping
Authors: Yair Kurzion, Torsten Möller, Roni Yagel
Published at Vis, 1998

We introduce a new approach for mapping texture on volumetric iso-surfaces and parametric surfaces. Our approach maps 2D images on surfaces while maintaining continuity and preserving the size of the mapped images on the models. Our approach is fully automatic. It eliminates the need for manual mapping of texture maps. We use the curvature of a surface at a point in order to continuously vary the scale of the mapped image. This makes our approach dependent only on local attributes of a point (position, normal and its derivatives) and independent of the global shape and topology of an object. Our method can map high resolution images on low resolution volumes, hence enhancing the visual appearance of rendered volume data. We describe a general framework useful for all surface types that have a C/sup 1/ continuous normal. We demonstrate the new method for painting volume data and for mapping cavities on volume data.
Smooth view-dependent level-of-detail control and its application to terrain rendering
Authors: Hugues Hoppe
Published at Vis, 1998

The key to real-time rendering of large-scale surfaces is to locally adapt surface geometric complexity to changing view parameters. Several schemes have been developed to address this problem of view-dependent level-of-detail control. Among these, the view-dependent progressive mesh (VDPM) framework represents an arbitrary triangle mesh as a hierarchy of geometrically optimized refinement transformations, from which accurate approximating meshes can be efficiently retrieved. In this paper we extend the general VDPM framework to provide temporal coherence through the run-time creation of geomorphs. These geomorphs eliminate "popping" artifacts by smoothly interpolating geometry. Their implementation requires new output-sensitive data structures, which have the added benefit of reducing memory use. We specialize the VDPM framework to the important case of terrain rendering. To handle huge terrain grids, we introduce a block-based simplification scheme that constructs a progressive mesh as a hierarchy of block refinements. We demonstrate the need for an accurate approximation metric during simplification. Our contributions are highlighted in a real-time flyover of a large, rugged terrain. Notably, the use of geomorphs results in visually smooth rendering even at 72 frames/sec on a graphics workstation.
Supporting detail-in-context for the DNA representation, H-curves
Authors: M. L. Lantin, Sheelagh Carpendale
Published at Vis, 1998

This paper presents a tool for the visual exploration of DNA sequences represented as H-curves. Although very long sequences can be plotted using H-curves, micro-features are lost as sequences get longer. We present a new three-dimensional distortion algorithm to allow the magnification of a sub-segment of an H-curve while preserving a global view of the curve. This is particularly appropriate for H-curves as they provide useful visual information at several resolutions. Our approach also extends the current possibilities of detail-in-context viewing in 3D. It provides a non-occluding, orthogonal technique that preserves uniform scaling within regions and maintains geometric continuity between regions.
Surface reconstruction with anisotropic density-scaled alpha shapes
Authors: Marek Teichmann, Michael V. Capps
Published at Vis, 1998

Generation of a three-dimensional model from an unorganized set of points is an active area of research in computer graphics. Alpha shapes can be employed to construct a surface which most closely reflects the object described by the points. However, no /spl alpha/-shape, for any value of /spl alpha/, can properly detail discontinuous regions of a model. We introduce herein two methods of improving the results of reconstruction using /spl alpha/-shapes: density-scaling, which modulates the value of a depending on the density of points in a region; and anisotropic shaping, which modulates the form of the /spl alpha/-ball based on point normals. We give experimental results that show the successes and limitations of our method.
Task-specific visualization design: a case study in operational weather forecasting
Authors: Lloyd Treinish
Published at Vis, 1998

Efforts to create highly generic visualizations, both content and interface, often when applied to non research oriented or operational activities are composed of several goals. Although these goals may appear to be related, they are often composed of distinct tasks. Generic solutions, even if domain-specific, may lack sufficient focus to be effective for such purposes. The design of different visualization tools matched to a set of tasks but built on top of a common framework with a similar approach to content is a promising alternative. This hypothesis is tested in detail by application to a demanding problem-operational weather forecasting.
The Gridfit algorithm: an efficient and effective approach to visualizing large amounts of spatial data
Authors: Daniel A. Keim, Annemarie Herrmann
Published at Vis, 1998

In a large number of applications, data is collected and referenced by their spatial locations. Visualizing large amounts of spatially referenced data on a limited-size screen display often results in poor visualizations due to the high degree of overplotting of neighboring datapoints. We introduce a new approach to visualizing large amounts of spatially referenced data. The basic idea is to intelligently use the unoccupied pixels of the display instead of overplotting data points. After formally describing the problem, we present two solutions which are based on: placing overlapping data points on the nearest unoccupied pixel; and shifting data points along a screen-filling curve (e.g., Hilbert-curve). We then develop a more sophisticated approach called Gridfit, which is based on a hierarchical partitioning of the data space. We evaluate all three approaches with respect to their efficiency and effectiveness and show the superiority of the Gridfit approach. For measuring the effectiveness, we not only present the resulting visualizations but also introduce mathematical effectiveness criteria measuring properties of the generated visualizations with respect to the original data such as distance- and position-preservation.
Three-dimensional visualization of microstructures
Authors: Marco Lanzagorta, Milo V. Kral, J. Edward Swan II, George Spanos, Robert Rosenberg, Eddy Kuo
Published at Vis, 1998

This case study describes a technique for the three-dimensional analysis of the internal microscopic structure (microstructure) of materials. This technique consists of incrementally polishing through a thin layer (approximately 0.2 /spl mu/m) of material, chemically etching the polished surface, applying reference marks, and performing optical or scanning electron microscopy on selected areas. The series of images are then processed employing AVS and other visualization software to obtain a 3D reconstruction of the material. We describe how we applied this technique to an alloy steel to study the morphology, connectivity, and distribution of cementite precipitates formed during thermal processing. The results showed microstructural features not previously identified with traditional 2D techniques.