DevLan/vispubs huggingface dataset:
A new object-order ray-casting algorithm
Authors: Benjamin Mora, Jean-Pierre Jessel, René Caubet
Published at Vis, 2002

Many direct volume rendering algorithms have been proposed during the last decade to render 256/sup 3/ voxels interactively. However a lot of limitations are inherent to all of them, like low-quality images, a small viewport size or a fixed classification. In contrast, interactive high quality algorithms are still a challenge nowadays. We introduce here an efficient and accurate technique called object-order ray-casting that can achieve up to 10 fps on current workstations. Like usual ray-casting, colors and opacities are evenly sampled along the ray, but now within a new object-order algorithm. Thus, it allows to combine the main advantages of both worlds in term of speed and quality. We also describe an efficient hidden volume removal technique to compensate for the loss of early ray termination.
A radial focus+context visualization for multi-dimensional functions
Authors: Sanjini Jayaraman, Chris North 0001
Published at Vis, 2002

The analysis of multidimensional functions is important in many engineering disciplines, and poses a major problem as the number of dimensions increases. Previous visualization approaches focus on representing three or fewer dimensions at a time. This paper presents a new focus+context visualization that provides an integrated overview of an entire multidimensional function space, with uniform treatment of all dimensions. The overview is displayed with respect to a user-controlled polar focal point in the function's parameter space. Function value patterns are viewed along rays that emanate from the focal point in all directions in the parameter space, and represented radially around the focal point in the visualization. Data near the focal point receives proportionally more screen space than distant data. This approach scales smoothly from two dimensions to 10-20, with a 1000 pixel range on each dimension.
Approximating normals for marching cubes applied to locally supported isosurfaces
Authors: Gregory M. Nielson, Adam Huang, Steve Sylvester
Published at Vis, 2002

We present some new methods for computing estimates of normal vectors at the vertices of a triangular mesh surface approximation to an isosurface which has been computed by the marching cube algorithm. These estimates are required for the smooth rendering of triangular mesh surfaces. The conventional method of computing estimates based upon divided difference approximations of the gradient can lead to poor estimates in some applications. This is particularly true for isosurfaces obtained from a field function, which is defined only for values near to the isosurface. We describe some efficient methods for computing the topology of the triangular mesh surface, which is used for obtaining local estimates of the normals. In addition, a new, one pass, approach for these types of applications is described and compared to existing methods.
Assisted navigation for large information spaces
Authors: Brent M. Dennis, Christopher G. Healey
Published at Vis, 2002

This paper presents a new technique for visualizing large, complex collections of data. The size and dimensionality of these datasets make them challenging to display in an effective manner. The images must show the global structure of spatial relationships within the dataset, yet at the same time accurately represent the local detail of each data element being visualized. We propose combining ideas from information and scientific visualization together with a navigation assistant, a software system designed to help users identify and explore areas of interest within their data. The assistant locates data elements of potential importance to the user, clusters them into spatial regions, and builds underlying graph structures to connect the regions and the elements they contain. Graph traversal algorithms, constraint-based viewpoint construction, and intelligent camera planning techniques can then be used to design animated tours of these regions. In this way, the navigation assistant can help users to explore any of the areas of interest within their data. We conclude by demonstrating how our assistant is being used to visualize a multidimensional weather dataset.
BLIC: Bi-Level Isosurface Compression
Authors: Gabriel Taubin
Published at Vis, 2002

In this paper we introduce a new and simple algorithm to compress isosurface data. This is the data extracted by isosurface algorithms from scalar functions defined on volume grids, and used to generate polygon meshes or alternative representations. In this algorithm the mesh connectivity and a substantial proportion of the geometric information are encoded to a fraction of a bit per marching cubes vertex with a context based arithmetic coder closely related to the JBIG binary image compression standard. The remaining optional geometric information that specifies the location of each marching cubes vertex more precisely along its supporting intersecting grid edge, is efficiently encoded in scan-order with the same mechanism. Vertex normals can optionally be computed as normalized gradient vectors by the encoder and included in the bitstream after quantization and entropy encoding, or computed by the decoder in a postprocessing smoothing step. These choices are determined by trade-offs associated with an in-core vs. out-of-core decoder structure. The main features of our algorithm are its extreme simplicity and high compression rates.
BM3D: motion estimation in time dependent volume data
Authors: Wim C. de Leeuw, Robert van Liere
Published at Vis, 2002

This paper describes BM3D: a method for the analysis of motion in time dependent volume data. From a sequence of volume data sets a sequence of vector data sets representing the movement of the data is computed. A block matching technique is used for the reconstruction of data movement. The derived vector field can be used for the visualization of time dependent volume data. The method is illustrated in two applications.
Bounded-distortion piecewise mesh parameterization
Authors: Olga Sorkine-Hornung, Daniel Cohen-Or, Rony Goldenthal, Dani Lischinski
Published at Vis, 2002

Many computer graphics operations, such as texture mapping, 3D painting, remeshing, mesh compression, and digital geometry processing, require finding a low-distortion parameterization for irregular connectivity triangulations of arbitrary genus 2-manifolds. This paper presents a simple and fast method for computing parameterizations with strictly bounded distortion. The new method operates by flattening the mesh onto a region of the 2D plane. To comply with the distortion bound, the mesh is automatically cut and partitioned on-the-fly. The method guarantees avoiding global and local self-intersections, while attempting to minimize the total length of the introduced seams. To our knowledge, this is the first method to compute the mesh partitioning and the parameterization simultaneously and entirely automatically, while providing guaranteed distortion bounds. Our results on a variety of objects demonstrate that the method is fast enough to work with large complex irregular meshes in interactive applications.
Case study on the adaptation of interactive visualization applications to Web-based production for operational mesoscale weather models
Authors: Lloyd Treinish
Published at Vis, 2002

Visualization is required for the effective utilization of data from a weather simulation. Appropriate mapping of user goals to the design of pictorial content has been useful in the development of interactive applications with sufficient bandwidth for timely access to the model data. When remote access to the model visualizations is required the limited bandwidth becomes the primary bottleneck. To help address these problems, visualizations are presented on a Web page as a meta-representation of the model output and serve as an index to simplify finding other visualizations of relevance. To provide consistency with extant interactive products and to leverage their cost of development, the aforementioned applications are adapted to automatically populate a Web site with images and interactions for an operational weather forecasting system.
Case study: A look of performance expression
Authors: Rumi Hiraga
Published at Vis, 2002

For most of the time, we enjoy and appreciate music performances as they are. Once we try to understand the performance not in subjective terms but in an objective way and share it with other people, visualizing the performance parameters is indispensable. In this paper, a figure for visualizing performance expressions is described. This figure helps people understand the cause and position of the performance expression as it has expressive cues, which coincide with the cognitive meaning of musical performance, and not by using only MIDI parameter values. The differences we hear between performances are clarified by visualized figures.
Case study: A virtual environment for genomic data visualization
Authors: R. Mark Adams, Blaze Stancampiano, Michael McKenna, David Small
Published at Vis, 2002

With the completion of the human genome sequence, and with the proliferation of genome-related annotation data, the need for scalable and more intuitive means for analysis becomes critical, At Variagenics and Small Design Firm, we have addressed this problem with a coherent three-dimensional space in which all data can be seen in a single context. This tool aids in integrating information at vastly divergent scales while maintaining accurate spatial and size relationships. Our visualization was successful in communicating to project teams with diverse backgrounds the magnitude and biological implication of genetic variation.
Case study: hardware-accelerated selective LIC volume rendering
Authors: Yasuko Suzuki, Issei Fujishiro, Li Chen, Hiroko Nakamura
Published at Vis, 2002

Line Integral Convolution (LIC) is a promising method for visualizing 2D dense flow fields. Direct extensions of the LIC method to 3D have not been considered very effective, because optical integration in viewing directions tends to spoil the coherent structures along 3D local streamlines. In our previous reports, we have proposed a selective approach to volume rendering of LIC solid texture using 3D significance map (S-map), derived from the characteristics of flow structures, and a specific illumination model for 3D streamlines. In this paper, we take full advantage of scalar volume rendering hardware, such as VolumePro, to realize a realtime 3D flow field visualization environment with the LIC volume rendering method.
Case study: Interactive rendering of adaptive mesh refinement data
Authors: Sanghun Park, Chandrajit L. Bajaj, Vinay Siddavanahalli
Published at Vis, 2002

Adaptive mesh refinement (AMR) is a popular computational simulation technique used in various scientific and engineering fields. Although AMR data is organized in a hierarchical multi-resolution data structure, the traditional volume visualization algorithms such as ray-casting and splatting cannot handle the form without converting it to a sophisticated data structure. In this paper, we present a hierarchical multi-resolution splatting technique using k-d trees and octrees for AMR data that is suitable for implementation on the latest consumer PC graphics hardware. We describe a graphical user interface to set transfer function and viewing/rendering parameters interactively. Experimental results obtained on a general purpose PC equipped with NVIDIA GeForce card are presented to demonstrate that the technique can interactively render AMR data (over 20 frames per second). Our scheme can easily be applied to parallel rendering of time-varying AMR data.
Case study: Interactive visualization for Internet security
Authors: Soon Tee Teoh, Kwan-Liu Ma, Shyhtsun Felix Wu, Xiaoliang Zhao
Published at Vis, 2002

Internet connectivity is defined by a set of routing protocols which let the routers that comprise the Internet backbone choose the best route for a packet to reach its destination. One way to improve the security and performance of Internet is to routinely examine the routing data. In this case study, we show how interactive visualization of Border Gateway Protocol (BGP) data helps characterize routing behavior, identify weaknesses in connectivity which could potentially cripple the Internet, as well as detect and explain actual anomalous events.
Case study: the "Office of Real Soon Now" for visualization
Authors: Samuel P. Uselton
Published at Vis, 2002

As part of a larger effort exploring alternative display systems, Lawrence Livermore National Laboratory has installed systems in two offices that extend and update the previously described "Office of Real Soon Now" project to improve the value for visualization tasks. These new systems use higher resolution projectors driven by workstations that run Unix-based applications via Linux and support hardware-accelerated 3D graphics, even across the boundary between displays.
Case study: Visual debugging of finite element codes
Authors: Patricia Crossno, David H. Rogers 0001, Christopher J. Garasi
Published at Vis, 2002

We present an innovative application developed at Sandia National Laboratories for visual debugging of unstructured finite element physics codes. Our tool automatically locates anomalous regions, such as inverted elements or nodes whose variable values lie outside a prescribed range, then extracts mesh subsets around these features for detailed examination. The subsets are viewed using color coding of variable values superimposed on the mesh structure. This allows the values and their relative spatial locations within the mesh to be correlated at a glance. Both topological irregularities and hot spots within the data stand out visually, allowing the user to explore the exact numeric values of the grid at surrounding points over time. We demonstrate the utility of this approach by debugging a cell inversion in a simulation of an exploding wire.
Case study: Visualization and analysis of high Rayleigh number - 3D convection in the Earth's mantle
Authors: Gordon Erlebacher, David A. Yuen, Fabien Dubuffet
Published at Vis, 2002

Data sets from large-scale simulations (up to 501/sup 3/ grid points) of mantle convection are analyzed with volume rendering of the temperature field and a new critical point analysis of the velocity field. As the Rayleigh number Ra is increased the thermal field develops increasingly thin plume-like structures along which heat is convected. These eventually break down and become turbulent. Visualization methods are used to distinguish between various models of heat conductivity and to develop an intuitive understanding of the structure of the flow.
Case study: Visualizing ocean flow vertical motions using Lagrangian-Eulerian time surfaces
Authors: Josh Grant, Gordon Erlebacher, James F. O'Brien
Published at Vis, 2002

Ocean model simulations commonly assume the ocean is hydrostatic, resulting in near zero vertical motion. The vertical motion found is typically associated with the variations of the thermocline depth over time, which are mainly a result of the development and movement of ocean fronts, eddies, and internal waves. A new technique, extended from Lagrangian-Eulerian Advection, is presented to help understand the variation of vertical motion associated with the change in thermocline depth over time. A time surface is correctly deformed in a single direction according to the flow. The evolution of the time surface is computed via a mixture of Eulerian and Lagrangian techniques. The dominant horizontal motion is textured onto the surface using texture advection, while both the horizontal and vertical motions are used to displace the surface. The resulting surface is shaded for enhanced contrast. Timings indicate that the overhead over standard 2D texture advection is no more than 12%.
Christmas tree case study: computed tomography as a tool for mastering complex real world objects with applications in computer graphics
Authors: Armin Kanitsar, Thomas Theußl, Lukas Mroz, Milos Srámek, Anna Vilanova, Balázs Csébfalvi, Jirí Hladuvka, Dominik Fleischmann, Michael Knapp, Rainer Wegenkittl, Petr Felkel, Stefan Röttger, Stefan Guthe, Werner Purgathofer, M. Eduard Gröller
Published at Vis, 2002

We report on using computed tomography (CT) as a model acquisition tool for complex objects in computer graphics. Unlike other modeling and scanning techniques the complexity of the object is irrelevant in CT, which naturally enables to model objects with, for example, concavities, holes, twists or fine surface details. Once the data is scanned, one can apply post-processing techniques for data enhancement, modification or presentation. For demonstration purposes we chose to scan a Christmas tree which exhibits high complexity which is difficult or even impossible to handle with other techniques. However, care has to be taken to achieve good scanning results with CT. Further, we illustrate post-processing by means of data segmentation and photorealistic as well as non-photorealistic surface and volume rendering techniques.
Comparative evaluation of visualization and experimental results using image comparison metrics
Authors: Hualin Zhou, Min Chen 0001, Michael F. Webster
Published at Vis, 2002

Comparative evaluation of visualization and experimental results is a critical step in computational steering. In this paper, we present a study of image comparison metrics for quantifying the magnitude of difference between visualization of a computer simulation and a photographic image captured from an experiment. We examined eleven metrics, including three spatial domain, four spatial-frequency domain and four HVS (human-vision system) metrics. Among these metrics, a spatial-frequency domain metric called 2nd-order Fourier comparison was proposed specifically for this work. Our study consisted of two stages: base cases and field trials. The former is a general study on a controlled comparison space using purposely selected data, and the latter involves imagery results from computational fluid dynamics and a rheological experiment. This study has introduced a methodological framework for analyzing image-level methods used in comparative visualization. For the eleven metrics considered, it has offered a set of informative indicators as to the strengths and weaknesses of each metric. In particular, we have identified three image comparison metrics that are effective in separating "similar" and "different" image groups. Our 2nd-order Fourier comparison metric has compared favorably with others in two of the three tests, and has shown its potential to be used for steering computer simulation quantitatively.
Compressing polygon mesh geometry with parallelogram prediction
Authors: Martin Isenburg, Pierre Alliez
Published at Vis, 2002

We present a generalization of the geometry coder by Touma and Gotsman (1998) to polygon meshes. We let the polygon information dictate where to apply the parallelogram rule that they use to predict vertex positions. Since polygons tend to be fairly planar and fairly convex, it is beneficial to make predictions within a polygon rather than across polygons. This, for example, avoids poor predictions due to a crease angle between polygons. Up to 90 percent of the vertices can be predicted this way. Our strategy improves geometry compression by 10 to 40 percent depending on (a) how polygonal the mesh is and (b) on the quality (planarity/convexity) of the polygons.
Computing singularities of 3D vector fields with geometric algebra
Authors: Stephen Mann, Alyn P. Rockwood
Published at Vis, 2002

Critical points of a vector field are key to their characterization. Their positions as well as their indexes are crucial for understanding vector fields. Considerable work exists in 2D, but less is available for 3D or higher dimensions. Geometric algebra is a derivative of Clifford algebra that not only enables a succinct definition of the index of a critical point in higher dimension; it also provides insight and computational pathways for calculating the index. We describe the problems in terms of geometric algebra and present an octree based solution using the algebra for finding critical points and their index in a 3D vector field.
CPR - curved planar reformation
Authors: Armin Kanitsar, Dominik Fleischmann, Rainer Wegenkittl, Petr Felkel, M. Eduard Gröller
Published at Vis, 2002

Visualization of tubular structures such as blood vessels is an important topic in medical imaging. One way to display tubular structures for diagnostic purposes is to generate longitudinal cross-sections in order to show their lumen, wall, and surrounding tissue in a curved plane. This process is called curved planar reformation (CPR). We present three different methods to generate CPR images. A tube-phantom was scanned with computed tomography (CT) to illustrate the properties of the different CPR methods. Furthermore we introduce enhancements to these methods: thick-CPR, rotating-CPR and multi-path-CPR.
Direct surface extraction from 3D freehand ultrasound images
Authors: Youwei Zhang, Robert Rohling, Dinesh K. Pai
Published at Vis, 2002

This paper presents a new technique for the extraction of surfaces from 3D ultrasound data. Surface extraction from ultrasound data is challenging for a number of reasons including noise and artifacts in the images and nonuniform data sampling. A method is proposed to fit an approximating radial basis function to the group of data samples. An explicit surface is then obtained by iso-surfacing the function. In most previous 3D ultrasound research, a pre-processing step is taken to interpolate the data into a regular voxel array and a corresponding loss of resolution. We are the first to represent the set of semi-structured ultrasound pixel data as a single function. From this we are able to extract surfaces without first reconstructing the irregularly spaced pixels into a regular 3D voxel array.
Efficient compression and rendering of multi-resolution meshes
Authors: Zachi Karni, Alexander Bogomjakov, Craig Gotsman
Published at Vis, 2002

We present a method to code the multiresolution structure of a 3D triangle mesh in a manner that allows progressive decoding and efficient rendering at a client machine. The code is based on a special ordering of the mesh vertices which has good locality and continuity properties, inducing a natural multiresolution structure. This ordering also incorporates information allowing efficient rendering of the mesh at all resolutions using the contemporary vertex buffer mechanism. The performance of our code is shown to be competitive with existing progressive mesh compression methods, while achieving superior rendering speed.