Conference stringclasses 6 values | Year int64 1.99k 2.03k | Title stringlengths 8 187 | DOI stringlengths 16 32 | Abstract stringlengths 128 7.15k ⌀ | Accessible bool 2 classes | Early bool 2 classes | AuthorNames-Deduped listlengths 1 24 | Award listlengths 0 2 | Resources listlengths 0 5 | ResourceLinks listlengths 0 10 |
|---|---|---|---|---|---|---|---|---|---|---|
Vis | 2,003 | Video visualization | 10.1109/VISUAL.2003.1250401 | Video data, generated by the entertainment industry, security and traffic cameras, video conferencing systems, video emails, and so on, is perhaps most time-consuming to process by human beings. In this paper, we present a novel methodology for "summarizing" video sequences using volume visualization techniques. We outline a system pipeline for capturing videos, extracting features, volume rendering video and feature data, and creating video visualization. We discuss a collection of image comparison metrics, including the linear dependence detector, for constructing "relative" and "absolute" difference volumes that represent the magnitude of variation between video frames. We describe the use of a few volume visualization techniques, including volume scene graphs and spatial transfer functions, for creating video visualization. In particular, we present a stream-based technique for processing and directly rendering video data in real time. With the aid of several examples, we demonstrate the effectiveness of using video visualization to convey meaningful information contained in video sequences. | false | false | [
"Gareth Daniel",
"Min Chen 0001"
] | [] | [] | [] |
Vis | 2,003 | Visibility based methods and assessment for detail-recovery | 10.1109/VISUAL.2003.1250407 | In this paper we propose a new method for the creation of normal maps for recovering the detail on simplified meshes and a set of objective techniques to metrically evaluate the quality of different recovering techniques. The proposed techniques, that automatically produces a normal-map texture for a simple 3D model that "imitates" the high frequency detail originally present in a second, much higher resolution one, is based on the computation of per-texel visibility and self-occlusion information. This information is used to define a point-to-point correspondence between simplified and hires meshes. Moreover, we introduce a number of criteria for measuring the quality (visual or otherwise) of a given mapping method, and provide efficient algorithms to implement them. Lastly, we apply them to rate different mapping methods, including the widely used ones and the new one proposed here. | false | false | [
"Marco Tarini",
"Paolo Cignoni",
"Roberto Scopigno"
] | [] | [] | [] |
Vis | 2,003 | Visibility culling using plenoptic opacity functions for large volume visualization | 10.1109/VISUAL.2003.1250391 | Visibility culling has the potential to accelerate large data visualization in significant ways. Unfortunately, existing algorithms do not scale well when parallelized, and require full re-computation whenever the opacity transfer function is modified. To address these issues, we have designed a Plenoptic Opacity Function (POF) scheme to encode the view-dependent opacity of a volume block. POFs are computed off-line during a pre-processing stage, only once for each block. We show that using POFs is (i) an efficient, conservative and effective way to encode the opacity variations of a volume block for a range of views, (ii) flexible for re-use by a family of opacity transfer functions without the need for additional off-line processing, and (iii) highly scalable for use in massively parallel implementations. Our results confirm the efficacy of POFs for visibility culling in large-scale parallel volume rendering; we can interactively render the Visible Woman dataset using software ray-casting on 32 processors, with interactive modification of the opacity transfer function on-the-fly. | false | false | [
"Jinzhu Gao",
"Jian Huang 0007",
"Han-Wei Shen",
"James Arthur Kohl"
] | [] | [] | [] |
Vis | 2,003 | Visualization experiences and issues in deep space exploration | 10.1109/VISUAL.2003.1250430 | Visualization tools play a key role in the exploration of outer space. Since it is difficult and expensive to send humans to other planets, immersive visualization of such hostile environments is as close as we will get for some time. Visualization is also used in a variety of supporting roles for deep space missions, from simulation and rehearsal of planned operations to analysis of spacecraft state to analysis of science data returned from a variety of instruments. The panelists will discuss their experiences in collecting data in deep space, transmitting it to Earth, processing and visualizing it here, and using the visualization to drive the continued mission. This closes the loop, making missions more responsive to their environment, particularly in-situ operations on planetary surfaces and within planetary atmospheres. | false | false | [
"John R. Wright",
"Scott C. Burleigh",
"Makoto Maruya",
"Scott Maxwell",
"René Pischel"
] | [] | [] | [] |
Vis | 2,003 | Visualization of noisy and biased volume data using first and second order derivative techniques | 10.1109/VISUAL.2003.1250397 | The quality of volume visualization depends strongly on the quality of the underlying data. In virtual colonoscopy, CT data should be acquired at a low radiation dose that results in a low signal-to-noise ratio. Alternatively, MRI data is acquired without ionizing radiation, but suffers from noise and bias (global signal fluctuations). Current volume visualization techniques often do not produce good results with noisy or biased data. This paper describes methods for volume visualization that deal with these imperfections. The techniques are based on specially adapted edge detectors using first and second order derivative filters. The filtering is integrated into the visualization process. The first order derivative method results in good quality images but suffers from localization bias. The second order method has better surface localization, especially in highly curved areas. It guarantees minimal detail smoothing resulting in a better visualization of polyps. | false | false | [
"Marc P. Persoon",
"Iwo Serlie",
"Frits H. Post",
"Roel Truyen",
"Frans Vos"
] | [] | [] | [] |
Vis | 2,003 | Visualization of steep breaking waves and thin spray sheets around a ship | 10.1109/VISUAL.2003.1250419 | The simulation of breaking of waves, the formation of thin spray sheets, and the entertainment of air around the next generation of naval surface combatants is an ongoing 3-year Department of Defense (DoD) Challenge Project. The goal of this project is a validated computation capability to model the full hydrodynamics around a surface combatant including all of the processes that affect mission and performance. Visualization of these large-scale simulations is paramount to understanding the complex physics involved. These simulations produce enormous data sets with both surface and volumetric qualities. Wave breaking, spray sheets, and air entertainment can be visualized using isosurfaces of scalar data. Visualization of quantities such as the vorticity field also provides insight into the dynamics of droplet and bubble formation. This paper documents the techniques used, results obtained, and lessons learned from the visualization of the hydrodynamics of naval vessels. | false | false | [
"Paul Adams",
"Douglas Dommermuth"
] | [] | [] | [] |
Vis | 2,003 | Visualization of volume data with quadratic super splines | 10.1109/VISUAL.2003.1250399 | We develop a new approach to reconstruct non-discrete models from gridded volume samples. As a model, we use quadratic trivariate super splines on a uniform tetrahedral partition /spl Delta/. The approximating splines are determined in a natural and completely symmetric way by averaging local data samples, such that appropriate smoothness conditions are automatically satisfied. On each tetra-hedron of /spl Delta/ , the quasi-interpolating spline is a polynomial of total degree two which provides several advantages including efficient computation, evaluation and visualization of the model. We apply Bernstein-Bezier techniques well-known in CAGD to compute and evaluate the trivariate spline and its gradient. With this approach the volume data can be visualized efficiently e.g., with isosurface ray-casting. Along an arbitrary ray the splines are univariate, piecewise quadratics and thus the exact intersection for a prescribed isovalue can be easily determined in an analytic and exact way. Our results confirm the efficiency of the quasi-interpolating method and demonstrate high visual quality for rendered isosurfaces. | false | false | [
"Christian Rössl",
"Frank Zeilfelder",
"Günther Nürnberger",
"Hans-Peter Seidel"
] | [] | [] | [] |
Vis | 2,003 | Visualization, optimization, business strategy: a case study | 10.1109/VISUAL.2003.1250416 | We describe a visualization application intended for operational use in formulating business strategy in the customer service arena. The visualization capability provided in this application implicitly allows the user to better formulate the objective function for large optimization runs which act to minimize costs based on certain input parameters. Visualization is necessary because many of the inputs to the optimization runs are themselves strategic business decisions which are not pre-ordained. Both information visualization presentations and three-dimensional visualizations are included to help users better understand the cost/benefit tradeoffs of these strategic business decisions. Here, visualization explicitly provides value not possible algorithmically, as the perceived benefit of different combinations of service level does not have an a priori mathematical formulation. Thus, we take advantage of the fundamental power of visualization, bringing the user's intuition and pattern recognition skills into the solution, while simultaneously taking advantage of the strength of algorithmic approaches to quickly and accurately find an optimal solution to a well-defined problem. | false | false | [
"Donna L. Gresh",
"Eugene I. Kelton"
] | [] | [] | [] |
Vis | 2,003 | Visualizing industrial CT volume data for nondestructive testing applications | 10.1109/VISUAL.2003.1250418 | This paper describes a set of techniques developed for the visualization of high-resolution volume data generated from industrial computed tomography for nondestructive testing (NDT) applications. Because the data are typically noisy and contain fine features, direct volume rendering methods do not always give us satisfactory results. We have coupled region growing techniques and a 2D histogram interface to facilitate volumetric feature extraction. The new interface allows the user to conveniently identify, separate or composite, and compare features in the data. To lower the cost of segmentation, we show how partial region growing results can suggest a reasonably good classification function for the rendering of the whole volume. The NDT applications that we work on demand visualization tasks including not only feature extraction and visual inspection, but also modeling and measurement of concealed structures in volumetric objects. An efficient filtering and modeling process for generating surface representation of extracted features is also introduced. Four CT data sets for preliminary NDT are used to demonstrate the effectiveness of the new visualization strategy that we have developed. | false | false | [
"Runzhen Huang",
"Kwan-Liu Ma",
"Patrick S. McCormick",
"William Ward"
] | [] | [] | [] |
Vis | 2,003 | Visualizing spatial and temporal variability in coastal observatories | 10.1109/VISUAL.2003.1250421 | In this paper, we describe a set of 3D and 4D visualization tools and techniques for CORIE, a complex environmental observation and forecasting system (EOFS) for the Columbia River. The Columbia River, a complex and highly variable estuary, is the target of numerous cross-disciplinary ecosystem research projects and is at the heart of multiple sustainable development issues with long reaching implications for the Pacific Northwest. However, there has been until recently no comprehensive and objective system available for modeling this environment, and as a consequence, researchers and agencies have had inadequate tools for evaluating the effects of natural resource management decisions. CORIE was designed to address this gap and is a major step towards the vision of a scalable, multi-use, real-time EOFS. Although CORIE already had a rich set of visualization tools, most of them produced 2D visualizations and did not allow for interactive visualization. Our work adds advanced interactive 3D tools to CORIE, which can be used for further inspection of the simulated and measured data. | false | false | [
"Walter Jiménez",
"Wagner Toledo Corrêa",
"Cláudio T. Silva",
"António M. Baptista"
] | [] | [] | [] |
Vis | 2,003 | Visually accurate multi-field weather visualization | 10.1109/VISUAL.2003.1250383 | Weather visualization is a difficult problem because it comprises volumetric multi-field data and traditional surface-based approaches obscure details of the complex three-dimensional structure of cloud dynamics. Therefore, visually accurate volumetric multi-field visualization of storm scale and cloud scale data is needed to effectively and efficiently communicate vital information to weather forecasters, improving storm forecasting, atmospheric dynamics models, and weather spotter training. We have developed a new approach to multi-field visualization that uses field specific, physically-based opacity, transmission, and lighting calculations per-field for the accurate visualization of storm and cloud scale weather data. Our approach extends traditional transfer function approaches to multi-field data and to volumetric illumination and scattering. | false | false | [
"Kirk Riley",
"David S. Ebert",
"Charles D. Hansen",
"Jason J. Levit"
] | [] | [] | [] |
Vis | 2,003 | Volume tracking using higher dimensional isosurfacing | 10.1109/VISUAL.2003.1250374 | Tracking and visualizing local features from a time-varying volumetric data allows the user to focus on selected regions of interest, both in space and time, which can lead to a better understanding of the underlying dynamics. In this paper, we present an efficient algorithm to track time-varying isosurfaces and interval volumes using isosurfacing in higher dimensions. Instead of extracting the data features such as isosurfaces or interval volumes separately from multiple time steps and computing the spatial correspondence between those features, our algorithm extracts the correspondence directly from the higher dimensional geometry and thus can more efficiently follow the user selected local features in time. In addition, by analyzing the resulting higher dimensional geometry, it becomes easier to detect important topological events and the corresponding critical time steps for the selected features. With our algorithm, the user can interact with the underlying time-varying data more easily. The computation cost for performing time-varying volume tracking is also minimized. | false | false | [
"Guangfeng Ji",
"Han-Wei Shen",
"Rephael Wenger"
] | [] | [] | [] |
Vis | 2,003 | Voxels on fire | 10.1109/VISUAL.2003.1250382 | We introduce a method for the animation of fire propagation and the burning consumption of objects represented as volumetric data sets. Our method uses a volumetric fire propagation model based on an enhanced distance field. It can simulate the spreading of multiple fire fronts over a specified isosurface without actually having to create that isosurface. The distance field is generated from a specific shell volume that rapidly creates narrow spatial bands around the virtual surface of any given isovalue. The complete distance field is then obtained by propagation from the initial bands. At each step multiple fire fronts can evolve simultaneously on the volumetric object. The flames of the fire are constructed from streams of particles whose movement is regulated by a velocity field generated with the hardware-accelerated Lattice Boltzmann Model (LBM). The LBM provides a physically-based simulation of the air flow around the burning object. The object voxels and the splats associated with the flame particles are rendered in the same pipeline so that the volume data with its external and internal structures can be displayed along with the fire. | false | false | [
"Ye Zhao 0004",
"Xiaoming Wei",
"Zhe Fan",
"Arie E. Kaufman",
"Hong Qin"
] | [] | [] | [] |
Vis | 2,003 | Which comes first, usability or utility? | 10.1109/VISUAL.2003.1250426 | Georges Grinstein Questions often asked when presenting some new model, new theory, new research or new visualization include: How useful or how usable is it? and Have you performed any tests? Visualization is an interface technology and as such includes not just software algorithms and techniques, but computer human interaction issues as well. This makes it draw from both areas, one appearing more focused on utility and the other on usability. One key step in the development of a new theory is the attempt to first solve a problem. That problem or question does not include a usability section; in some domain it may not even contain a utility one from most people's perspectives. We discuss both sides of the issue to clarify the role of each in the development of new visualization technologies. Position Statement Alfred Kobsa In the HCI literature one can find studies which conclude that ease of use is more important than usefulness (Hubona & Blanton 1996), that the opposite holds true (Liao and Landry 2000), and that ease of use is more important for females while the usefulness is more important for males (Yuen and Ma 2002). In this panel contribution, we will present several user studies with information visualization systems, ranging from lab experiments with closed questions to longitudinal adoption studies with administrative data analysts (Gonzales & Kobsa, 2003; Kobsa 2001, 2003; Mark et al. 2003). -------------------------------------------a e-mail: grinstein@cs.uml.edu e-mail: kobsa@uci.edu e-mail: plaisant@cs.umd.edu e-mail ben@cs.umd.edu e-mail statsko@cc.gatech.edu Consistent with general HCI research, the results show that both factors are important in certain situations, but do not indicate a clear superiority of one factor over the other. Position Statement Catherine Plaisant Is an airplane a better vehicle than a Jaguar, a mountain bicycle or a kid scooter? It all depends of where you need to go, what your goal for the travel is, how old you are, what terrain you will encounter on the way, how long you can spend learning, and many other parameters. All those vehicles are fairly usable but they all require training except for adults using the scooter, and their utility varies enormously as a function of the task and the user. The average car drivers benefit from years of human factor engineering and a large amount of standardization, allowing them to switch from a pickup truck to a convertible in a snap. Similarly, the success of a visualization tool depends on how well it fits the needs of the users it attempts to serve, and the tasks they want to accomplish. If utility may come first for an expert tool (e.g. for discovery tasks requires days of data examination and manipulation), usability has to come first in public access information systems that requires "immediate usability" (e.g. interactive displays of census statistics) otherwise users will walk away frustrated. Usability design principles imply that designers and evaluators understand the needs of users to decide which one of the two utility or usability comes first, and to set levels of required utility and usability. Utility and usability are both attainable goals that make each other stronger. Like others, we at the University of Maryland have been developing visualization techniques and have struggled over the years to find the best way to evaluate their benefits. Many evaluations have been controlled experiments and we have found that the most useful evaluations were multi-faceted, including qualitative and quantitative measurements or performance, preference and learnability, and I will be show examples from our research. Often we also find that the observations gathered during the experiment can be as informative as the collected measurements. More recently we have been promoting the development of benchmark datasets and tasks that will allow better comparisons between tools and techniques. We have been involved in the 1st InfoVis contest, which calls for the submission of case studies of pairwise comparison of trees. Three pairs of datasets were provided: philogenies, classifications and file system usage data, 605 Proceedings of the 14th IEEE Visualization Conference (VIS’03) 0-7695-2030-8/03 $ 17.00 © 2003 IEEE and open ended tasks described. Accepted submissions will seed an online repository that can be enhanced over time with additional datasets, tasks, case studies and controlled experiment results. I will report on the results of the contest and reflect on how evaluation repository and benchmark datasets might help us understand how to judge the usability and utility of our tools. The contest is at: http://www.cs.umd.edu/hcil/iv03contest/ Position Statement Ben Shneiderman The answer to the question of usability or utility first depends on your definition of usability. For me, usability is more than the color of widgets and placement of text. Usability is about understanding, stating, and serving user needs. Since these needs are the requirements that shape the tool, they determine the utility. The design of excellent tools depends upon understanding how they will be used; therefore usability is a pre-requisite for successful utility. Position Statement John T. Stasko If the question is, "Which comes first, utility or usability?" my answer is "yes". Both notions are vitally important in the development of information visualization techniques and systems, and they are just two sides of the same coin. When the field of information visualization formed and first grew, the computer graphics and visualization aspects dominated. More recently, an increasing emphasis on the HCI aspects of the field has emerged as we strive to better understand how people can truly benefit from our ideas. When an information visualization technique is implemented in a system, the usability component is crucial. Poor interface design can hamper adoption and cloud the utility benefits that may be possible. In information visualization, usability typically does not equate with the common notion of a system being easy to learn. Information visualization systems are complex and they often will be used extensively for long periods of time. Consequently, making a system efficient and natural to use, making functions and operations visible, and simply paying attention to the user interface are key components. This is especially true in systems where interaction and multiple views are essential. For any information visualization technique to be adopted beyond the initial idea generation, there must be some utility or value in that technique. Our field is not about making pretty pictures. It is about helping people with the complex tasks involved in data analysis and understanding. We need to do a better job of articulating the cognitive tasks that occur in data analysis (location, correlation, emphasis, association, etc.) and articulating how information visualization techniques and systems can help with these tasks. Ultimately, a kind of natural selection will occur: systems with utility and value will be adopted and used, while others will quietly fade away. | false | false | [
"Georges G. Grinstein",
"Alfred Kobsa",
"Catherine Plaisant",
"Ben Shneiderman",
"John T. Stasko"
] | [] | [] | [] |
InfoVis | 2,003 | A model of multi-scale perceptual organization in information graphics | 10.1109/INFVIS.2003.1249005 | We propose a new method for assessing the perceptual organization of information graphics, based on the premise that the visual structure of an image should match the structure of the data it is intended to convey. The core of our method is a new formal model of one type of perceptual structure, based on classical machine vision techniques for analyzing an image at multiple resolutions. The model takes as input an arbitrary grayscale image and returns a lattice structure describing the visual organization of the image. We show how this model captures several aspects of traditional design aesthetics, and we describe a software tool that implements the model to help designers analyze and refine visual displays. Our emphasis here is on demonstrating the model's potential as a design aid rather than as a description of human perception, but given its initial promise we propose a variety of ways in which the model could be extended and validated. | false | false | [
"Martin Wattenberg",
"Danyel Fisher"
] | [] | [] | [] |
InfoVis | 2,003 | A virtual workspace for hybrid multidimensional scaling algorithms | 10.1109/INFVIS.2003.1249013 | In visualising multidimensional data, it is well known that different types of algorithms to process them. Data sets might be distinguished according to volume, variable types and distribution, and each of these characteristics imposes constraints upon the choice of applicable algorithms for their visualization. Previous work has shown that a hybrid algorithmic approach can be successful in addressing the impact of data volume on the feasibility of multidimensional scaling (MDS). This suggests that hybrid combinations of appropriate algorithms might also successfully address other characteristics of data. This paper presents a system and framework in which a user can easily explore hybrid algorithms and the data flowing through them. Visual programming and a novel algorithmic architecture let the user semi-automatically define data flows and the co-ordination of multiple views. | false | false | [
"Greg Ross",
"Matthew Chalmers"
] | [] | [] | [] |
InfoVis | 2,003 | An experimental evaluation of continuous semantic zooming in program visualization | 10.1109/INFVIS.2003.1249021 | This paper presents the results of an experiment aimed at investigating how different methods of viewing visual programs affect users' understanding. The first two methods used traditional flat and semantic zooming models of program representation; the third is a new representation that uses semantic zooming combined with blending and proximity. The results of several search tasks performed by approximately 80 participants showed that the new method resulted in both faster and more accurate searches than the other methods. | false | false | [
"Kenneth L. Summers",
"Timothy E. Goldsmith",
"Steve Kubica",
"Thomas P. Caudell"
] | [] | [] | [] |
InfoVis | 2,003 | BARD: A visualization tool for biological sequence analysis | 10.1109/INFVIS.2003.1249029 | We present BARD (biological arc diagrams), a visualization tool for biological sequence analysis. The development of BARD began with the application of Wattenberg's arc diagrams (Wattenberg, 2002) to results from sequence analysis programs, such as BLAST (Atschul et al., 1990). In this paper, we extend the initial arc diagram concept in two ways: 1) by separating the visualization method from the underlying matching algorithm and 2) by expanding the types of matches to include inexact matches, complemented palindrome matches, and inter-sequence matches. BARD renders each type of match distinctly, resulting in a powerful tool to quickly understand sequence similarities and differences. We illustrate the power of BARD by applying the technique to a comparative sequence analysis of the human pathogenic fungi Cryptococcus neoformans. | false | false | [
"Rhazes Spell",
"Rachael Brady",
"Fred Dietrich"
] | [] | [] | [] |
InfoVis | 2,003 | Between aesthetics and utility: designing ambient information visualizations | 10.1109/INFVIS.2003.1249031 | Unlike traditional information visualization, ambient information visualizations reside in the environment of the user rather than on the screen of a desktop computer. Currently, most dynamic information that is displayed in public places consists of text and numbers. We argue that information visualization can be employed to make such dynamic data more useful and appealing. However, visualizations intended for non-desktop spaces will have to both provide valuable information and present an attractive addition to the environment - they must strike a balance between aesthetical appeal and usefulness. To explore this, we designed a real-time visualization of bus departure times and deployed it in a public space, with about 300 potential users. To make the presentation more visually appealing, we took inspiration from a modern abstract artist. The visualization was designed in two passes. First, we did a preliminary version that was presented to and discussed with prospective users. Based on their input, we did a final design. We discuss the lessons learned in designing this and previous ambient information visualizations, including how visual art can be used as a design constraint, and how the choice of information and the placement of the display affect the visualization. | false | false | [
"Tobias Skog",
"Sara Ljungblad",
"Lars Erik Holmquist"
] | [] | [] | [] |
InfoVis | 2,003 | Causality visualization using animated growing polygons | 10.1109/INFVIS.2003.1249025 | We present Growing Polygons, a novel visualization technique for the graphical representation of causal relations and information flow in a system of interacting processes. Using this method, individual processes are displayed as partitioned polygons with color-coded segments showing dependencies to other processes. The entire visualization is also animated to communicate the dynamic execution of the system to the user. The results from a comparative user study of the method show that the Growing Polygons technique is significantly more efficient than the traditional Hasse diagram visualization for analysis tasks related to deducing information flow in a system for both small and large executions. Furthermore, our findings indicate that the correctness when solving causality tasks is significantly improved using our method. In addition, the subjective ratings of the users rank the method as superior in all regards, including usability, efficiency, and enjoyability. | false | false | [
"Niklas Elmqvist",
"Philippas Tsigas"
] | [] | [] | [] |
InfoVis | 2,003 | Compound brushing | 10.1109/INFVIS.2003.1249024 | This paper proposes a conceptual model called compound brushing for modeling the brushing techniques used in dynamic data visualization. In this approach, brushing techniques are modeled as higraphs with five types of basic entities: data, selection, device, renderer, and transformation. Using this model, a flexible visual programming tool is designed not only to configure/control various common types of brushing techniques currently used in dynamic data visualization, but also to investigate new brushing techniques. | false | false | [
"Hong Chen"
] | [] | [] | [] |
InfoVis | 2,003 | Constant density displays using diversity sampling | 10.1109/INFVIS.2003.1249019 | The Informedia Digital Video Library user interface summarizes query results with a collage of representative keyframes. We present a user study in which keyframe occlusion caused difficulties. To use the screen space most efficiently to display images, both occlusion and wasted whitespace should be minimized. Thus optimal choices will tend toward constant density displays. However, previous constant density algorithms are based on global density, which leads to occlusion and empty space if the density is not uniform. We introduce an algorithm that considers the layout of individual objects and avoids occlusion altogether. Efficiency concerns are important for dynamic summaries of the Informedia Digital Video Library, which has hundreds of thousands of shots. Posting multiple queries that take into account parameters of the visualization as well as the original query reduces the amount of work required. This greedy algorithm is then compared to an optimal one. The approach is also applicable to visualizations containing complex graphical objects other than images, such as text, icons, or trees. | false | false | [
"Mark Derthick",
"Michael G. Christel",
"Alex Hauptmann 0001",
"Howard D. Wactlar"
] | [] | [] | [] |
InfoVis | 2,003 | Conveying shape with texture: an experimental investigation of the impact of texture type on shape categorization judgments | 10.1109/INFVIS.2003.1249022 | As visualization researchers, we are interested in gaining a better understanding of how to effectively use texture to facilitate shape perception. If we could design the ideal texture pattern to apply to an arbitrary smoothly curving shape to be most accurately and effectively perceived, what would the characteristics of that texture pattern be? In this paper we describe the results of a comprehensive controlled observer experiment intended to yield insight into that question. Here, we report the results of a new study comparing the relative accuracy of observers' judgments of shape type (elliptical, cylindrical, hyperbolic or flat) and shape orientation (convex, concave, both, or neither) for local views of boundary masked quadric surface patches under six different principal direction texture pattern conditions plus two texture conditions (an isotropic pattern and a non-principal direction oriented anisotropic pattern), under both perspective and orthographic projection conditions and from both head-on and oblique viewpoints. Our results confirm the hypothesis that accurate shape perception is facilitated to a statistically significantly greater extent by some principal direction texture patterns than by others. Specifically, we found that, for both views, under conditions of perspective projection, participants more often correctly identified the shape category and the shape orientation when the surface was textured with the pattern that contained oriented energy along both the first and second principal directions only than in the case of any other texture condition. Patterns containing markings following only one of the principal directions, or containing information along other directions in addition to the principal directions yielded poorer performance overall. | false | false | [
"Sunghee Kim",
"Haleh Hagh-Shenas",
"Victoria Interrante"
] | [] | [] | [] |
InfoVis | 2,003 | Coordinated graph and scatter-plot views for the visual exploration of microarray time-series data | 10.1109/INFVIS.2003.1249023 | Microarrays are relatively new, high-throughput data acquisition technology for investigating biological phenomena at the micro-level. One of the more common procedures for microarray experimentation is that of the microarray time-course experiment. The product of microarray time-course experiment is time-series data, which subject to proper analysis has the potential to have significant impact on the diagnosis, treatment, and prevention of diseases. While existing information visualization techniques go some way to making microarray time-series data more manageable, requirements analysis has revealed significant limitations. The main finding was that users were unable to uncover and quantify common changes in value over a specified time-period. This paper describes a novel technique that provides this functionality by allowing the user to visually formulate and modify measurable queries with separate time-period and condition components. These visual queries are supported by the combination of a traditional value against time graph representation of the data with a complementary scatter-plot representation of a specified time-period. The multiple views of the visualization are coordinated so that the user can formulate and modify queries with rapid reversible display of query results in the traditional value against time graph format. | false | false | [
"Paul Craig",
"Jessie Kennedy"
] | [] | [] | [] |
InfoVis | 2,003 | Design choices when architecting visualizations | 10.1109/INFVIS.2003.1249007 | In this paper, we focus on some of the key design decisions we faced during the process of architecting a visualization system and present some possible choices, with their associated advantages and disadvantages. We frame this discussion within the context of Rivet, our general visualization environment designed for rapidly prototyping interactive, exploratory visualization tools for analysis. As we designed increasingly sophisticated visualizations, we needed to refine Rivet in order to be able to create these richer displays for larger and more complex data sets. The design decisions we discuss in this paper include: the internal data model, data access, semantic meta-data information the visualization can use to create effective visual decodings, the need for data transformations in a visualization tool, modular objects for flexibility, and the tradeoff between simplicity and expressiveness when providing methods for creating visualizations. | false | false | [
"Diane Tang",
"Chris Stolte",
"Robert P. Bosch Jr."
] | [] | [] | [] |
InfoVis | 2,003 | Developing architectural lighting representations | 10.1109/INFVIS.2003.1249032 | This paper reports on the development of a visualization system for architectural lighting designers. It starts by motivating the problem as both complex in its physics and social organization. Three iterations of prototypes for displaying time and space varying phenomena are discussed. Fieldwork is presented to identify where in practice they will be most effective. A set of user studies, one of which is analyzed in fine-grained detail, show how building designers incorporate visualization on hypothetical design problems. This has positive implications for both energy efficiency and lighting quality in buildings. | false | false | [
"Daniel C. Glaser",
"Roger Tan",
"John F. Canny",
"Ellen Yi-Luen Do"
] | [] | [] | [] |
InfoVis | 2,003 | Dynamic visualization of transient data streams | 10.1109/INFVIS.2003.1249014 | We introduce two dynamic visualization techniques using multidimensional scaling to analyze transient data streams such as newswires and remote sensing imagery. While the time-sensitive nature of these data streams requires immediate attention in many applications, the unpredictable and unbounded characteristics of this information can potentially overwhelm many scaling algorithms that require a full re-computation for every update. We present an adaptive visualization technique based on data stratification to ingest stream information adaptively when influx rate exceeds processing rate. We also describe an incremental visualization technique based on data fusion to project new information directly onto a visualization subspace spanned by the singular vectors of the previously processed neighboring data. The ultimate goal is to leverage the value of legacy and new information and minimize re-processing of the entire dataset in full resolution. We demonstrate these dynamic visualization results using a newswire corpus and a remote sensing imagery sequence. | false | false | [
"Pak Chung Wong",
"Harlan Foote",
"Dan Adams",
"Wendy Cowley",
"James J. Thomas"
] | [] | [] | [] |
InfoVis | 2,003 | Edgelens: an interactive method for managing edge congestion in graphs | 10.1109/INFVIS.2003.1249008 | An increasing number of tasks require people to explore, navigate and search extremely complex data sets visualized as graphs. Examples include electrical and telecommunication networks, Web structures, and airline routes. The problem is that graphs of these real world data sets have many interconnected nodes, ultimately leading to edge congestion: the density of edges is so great that they obscure nodes, individual edges, and even the visual information beneath the graph. To address this problem we developed an interactive technique called EdgeLens. An EdgeLens interactively curves graph edges away for a person's focus attention without changing the node positions. This opens up sufficient space to disambiguate node and edge relationships and to see underlying information while still preserving node layout. Initially two methods of creating this interaction were developed and compared in a user study. The results of this study were used in the selection of a basic approach and the subsequent development of the EdgeLens. We then improved the EdgeLens through use of transparency and colour and by allowing multiple lenses to appear on the graph. | false | false | [
"Nelson Wong",
"Sheelagh Carpendale",
"Saul Greenberg"
] | [] | [] | [] |
InfoVis | 2,003 | Empirical comparison of dynamic query sliders and brushing histograms | 10.1109/INFVIS.2003.1249020 | Dynamic queries facilitate rapid exploration of information by real-time visual display of both query formulation and results. Dynamic query sliders are linked to the main visualization to filter data. A common alternative to dynamic queries is to link several simple visualizations, such as histograms, to the main visualization with a brushing interaction strategy. Selecting data in the histograms highlights that data in the main visualization. We compare these two approaches in an empirical experiment on DataMaps, a geographic data visualization tool. Dynamic query sliders resulted in better performance for simple range tasks, while brushing histograms was better for complex trend evaluation and attribute relation tasks. Participants preferred brushing histograms for understanding relationships between attributes and the rich information they provided. | false | false | [
"Qing Li",
"Chris North 0001"
] | [] | [] | [] |
InfoVis | 2,003 | Exploding the frame: designing for wall-size computer displays | 10.1109/INFVIS.2003.1249002 | High-resolution wall-size digital displays present significant new and different visual space to show and see imagery. The author has been working with two wall-size digital displays at Princeton University for five years and directing and producing IMAX films for a decade, and he has noted some unique design considerations for creating effective visual images when they are spread across entire walls. The author suggests these "frameless" screens - where images are so large we need to look around to see the entire field - need different ways of thinking about image design and visualization. Presenting such things as scale and detail take on new meaning when they can be displayed life-size and not shown in the context of one or many small frames such as we see everywhere. These design ideas will be of use for pervasive computing, interface research and design, interactive design, control design, representations of massive data sets, and creating effective displays of data for research and education. | false | false | [
"Ben Shedd"
] | [] | [] | [] |
InfoVis | 2,003 | Exploring high-D spaces with multiform matrices and small multiples | 10.1109/INFVIS.2003.1249006 | We introduce an approach to visual analysis of multivariate data that integrates several methods from information visualization, exploratory data analysis (EDA), and geovisualization. The approach leverages the component-based architecture implemented in GeoVISTA Studio to construct a flexible, multiview, tightly (but generically) coordinated, EDA toolkit. This toolkit builds upon traditional ideas behind both small multiples and scatterplot matrices in three fundamental ways. First, we develop a general, multiform, bivariate matrix and a complementary multiform, bivariate small multiple plot in which different bivariate representation forms can be used in combination. We demonstrate the flexibility of this approach with matrices and small multiples that depict multivariate data through combinations of: scatterplots, bivariate maps, and space-filling displays. Second, we apply a measure of conditional entropy to (a) identify variables from a high-dimensional data set that are likely to display interesting relationships and (b) generate a default order of these variables in the matrix or small multiple display. Third, we add conditioning, a kind of dynamic query/filtering in which supplementary (undisplayed) variables are used to constrain the view onto variables that are displayed. Conditioning allows the effects of one or more well understood variables to be removed form the analysis, making relationships among remaining variables easier to explore. We illustrate the individual and combined functionality enabled by this approach through application to analysis of cancer diagnosis and mortality data and their associated covariates and risk factors. | false | false | [
"Alan M. MacEachren",
"Xiping Dai",
"Frank Hardisty",
"Diansheng Guo",
"Eugene Lengerich"
] | [] | [] | [] |
InfoVis | 2,003 | FundExplorer: supporting the diversification of mutual fund portfolios using context treemaps | 10.1109/INFVIS.2003.1249027 | An equity mutual fund is a financial instrument that invests in a set of stocks. Any two different funds may partially invest in some of the same stocks, thus overlap is common. Portfolio diversification aims at spreading an investment over many different stocks in search of greater returns. Helping people with portfolio diversification is challenging because it requires informing them about both their current portfolio of stocks held through funds and the other stocks in the market not invested in yet. Current stock/fund visualization systems either waste screen real estate and visualization of all data points. We have developed a system called FundExplorer that implements a distorted treemap to visualize both the amount of money invested in a person's fund portfolio and the context of remaining market stocks. The FundExplorer system enables people to interactively explore diversification possibilities with their portfolios. | false | false | [
"Christoph Csallner",
"Marcus Handte",
"Othmar Lehmann",
"John T. Stasko"
] | [] | [] | [] |
InfoVis | 2,003 | IEEE Symposium on Information Visualization 2003 (IEEE Cat. No.03TH8714) | 10.1109/INFVIS.2003.1249000 | The following topics are dealt with: computer displays; multiscaling; graphs; high dimensionality; occlusion; visualization evaluation; linking and design studies. | false | false | [
"Tamara Munzner",
"Steven C. North"
] | [] | [] | [] |
InfoVis | 2,003 | Improving Hybrid MDS with Pivot-Based Searching | 10.1109/INFVIS.2003.1249012 | An algorithm is presented for the visualization of multidimensional abstract data, building on a hybrid model introduced at Info Vis 2002. The most computationally complex stage of the original model involved performing a nearest-neighbour search for every data item. The complexity of this phase has been reduced by treating all high-dimensional relationships as a set of discretised distances to a constant number of randomly selected pivot items. In improving this computational bottleneck, the complexity is reduced to from O(N/sub 1/2 /N) to O(N/sub 5/4/). As well as documenting this improvement, the paper describes evaluation with a data set of 108000 14-dimensional items; a considerable increase on the size of data previously tested. Results illustrate that the reduction in complexity is reflected in significantly improved run times and that no negative impact is made upon the quality of layout produced. | false | false | [
"Alistair Morrison",
"Matthew Chalmers"
] | [] | [] | [] |
InfoVis | 2,003 | Information esthetics: from MoMa to wall street | 10.1109/INFVIS.2003.1249003 | My after-dinner talk has the goal of being a visual dessert, showing some of the information designs and explorations that I've put together in the last twenty years as a practicing designer and more recently, as an artist. I'll show the ones that people reacted to most strongly; partly to soothe and entertain, but partly in the hopes that some of the techniques I apply might be useful in the work of other attendees.
To that end I'll present a simplified Knowledge Acquisition Pipeline, a kind of designer's checklist that has been valuable in guiding my students and me while creating information-rich displays and user interfaces. It helps organize the wide variety of techniques available to us as information designers. But more--it helps us understand why they might work, where they might be useful in a design, and even what types of information can best be shown with which techniques. It works as a generative guideline as well as an intellectual framework. I'll tie parts of the examples back to this pipeline to show how it works in practice.
The application of this pipeline to visualization work suggests that as a field we are getting good value out of our understanding of the earlier processes--those having to do with sensation and perception. But later processes still have a lot of room for exploration: the visual attributes we use to represent data can often be made more specific, and therefore both more communicative and easier to decode. The world is richer than we can describe with circular nodes and linear links. And when we can get a visual vocabulary from the target audience, their own higher level semantic relationships may also be more easily absorbed and manipulated. I suggest that what such "illustrative information displays" lose in generality they more than make up in ease of interpretation and viewer engagement. | false | false | [
"W. Bradford Paley"
] | [] | [] | [] |
InfoVis | 2,003 | Intelligently resolving point occlusion | 10.1109/INFVIS.2003.1249018 | Large and high-dimensional data sets mapped to low-dimensional visualizations often result in perceptual ambiguities. One such ambiguity is overlap or occlusion that occurs when the number of records exceeds the number of unique locations in the presentation or when there exist two or more records that map to the same location. To lessen the affect of occlusion, non-standard visual attributes (i.e. shading and/or transparency) are applied, or such records may be remapped to a corresponding jittered location. The resulting mapping efficiently portrays the crowding of records but fails to provide the insight into the relationship between the neighboring records. We introduce a new interactive technique that intelligibly organizes overlapped points, a neural network-based smart jittering algorithm. We demonstrate this technique on a scatter plot, the most widely used visualization. The algorithm can be applied to other one, two, and multi-dimensional visualizations which represent data as points, including 3-dimensional scatter plots, RadViz, polar coordinates. | false | false | [
"Marjan Trutschl",
"Georges G. Grinstein",
"Urska Cvek"
] | [] | [] | [] |
InfoVis | 2,003 | Interactive hierarchical dimension ordering, spacing and filtering for exploration of high dimensional datasets | 10.1109/INFVIS.2003.1249015 | Large number of dimensions not only cause clutter in multi-dimensional visualizations, but also make it difficult for users to navigate the data space. Effective dimension management, such as dimension ordering, spacing and filtering, is critical for visual exploration of such datasets. Dimension ordering and spacing explicitly reveal dimension relationships in arrangement-sensitive multidimensional visualization techniques, such as parallel coordinates, star glyphs, and pixel-oriented techniques. They facilitate the visual discovery of patterns within the data. Dimension filtering hides some of the dimensions to reduce clutter while preserving the major information of the dataset. In this paper, we propose an interactive hierarchical dimension ordering, spacing and filtering approach, called DOSFA. DOSFA is based on dimension hierarchies derived from similarities among dimensions. It is scalable multi-resolution approach making dimensional management a tractable task. On the one hand, it automatically generates default settings for dimension ordering, spacing and filtering. On the other hand, it allows users to efficiently control all aspects of this dimension management process via visual interaction tools for dimension hierarchy manipulation. A case study visualizing a dataset containing over 200 dimensions reveals high dimensional visualization techniques. | false | false | [
"Jing Yang 0001",
"Wei Peng",
"Matthew O. Ward",
"Elke A. Rundensteiner"
] | [
"TT"
] | [] | [] |
InfoVis | 2,003 | Mapping nominal values to numbers for effective visualization | 10.1109/INFVIS.2003.1249016 | Data sets with a large number of nominal variables, some with high cardinality, are becoming increasingly common and need to be explored. Unfortunately, most existing visual exploration displays are designed to handle numeric variables only. When importing data sets with nominal values into such visualization tools, most solutions to date are rather simplistic. Often, techniques that map nominal values to numbers do not assign order or spacing among the values in a manner that conveys semantic relationships. Moreover, displays designed for nominal variables usually cannot handle high cardinality variables well. This paper addresses the problem of how to display nominal variables in general-purpose visual exploration tools designed for numeric variables. Specifically, we investigate (1) how to assign order and spacing among the nominal values, and (2) how to reduce the number of distinct values to display. We propose that nominal variables be pre-processed using a distance-quantification-classing (DQC) approach before being imported into a visual exploration tool. In the distance step, we identify a set of independent dimensions that can be used to calculate the distance between nominal values. In the quantification step, we use the independent dimensions and the distance information to assign order and spacing among the nominal values. In the classing step, we use results from the previous steps to determine which values within a variable are similar to each other and thus can be grouped together. Each step in the DQC approach can be accomplished by a variety of techniques. We extended the XmdvTool package to incorporate this approach. We evaluated our approach on several data sets using a variety of evaluation measures. | false | false | [
"Geraldine E. Rosario",
"Elke A. Rundensteiner",
"David C. Brown",
"Matthew O. Ward"
] | [] | [] | [] |
InfoVis | 2,003 | MoireGraphs: radial focus+context visualization and interaction for graphs with visual nodes | 10.1109/INFVIS.2003.1249009 | Graph and tree visualization techniques enable interactive exploration of complex relations while communicating topology. However, most existing techniques have not been designed for situations where visual information such as images is also present at each node and must be displayed. This paper presents MoireGraphs to address this need. MoireGraphs combine a new focus+context radial graph layout with a suite of interaction techniques (focus strength changing, radial rotation, level highlighting, secondary foci, animated transitions and node information) to assist in the exploration of graphs with visual nodes. The method is scalable to hundreds of displayed visual nodes. | false | false | [
"T. J. Jankun-Kelly",
"Kwan-Liu Ma"
] | [] | [] | [] |
InfoVis | 2,003 | Multiscale Visualization of Small World Networks | 10.1109/INFVIS.2003.1249011 | Many networks under study in information visualization are "small world" networks. These networks first appeared in the study of social networks and were shown to be relevant models in other application domains such as software reverse engineering and biology. Furthermore, many of these networks actually have a multiscale nature: they can be viewed as a network of groups that are themselves small world networks. We describe a metric that has been designed in order to identify the weakest edges in a small world network leading to an easy and low cost filtering procedure that breaks up a graph into smaller and highly connected components. We show how this metric can be exploited through an interactive navigation of the network based on semantic zooming. Once the network is decomposed into a hierarchy of sub-networks, a user can easily find groups and subgroups of actors and understand their dynamics. | false | false | [
"David Auber",
"Yves Chiricota",
"Fabien Jourdan",
"Guy Melançon"
] | [] | [] | [] |
InfoVis | 2,003 | Smooth and efficient zooming and panning | 10.1109/INFVIS.2003.1249004 | Large 2D information spaces, such as maps, images, or abstract visualizations, require views at various level of detail: close ups to inspect details, overviews to maintain (literally) an overview. Users often switch between these views. We discuss how smooth animations from one view to another can be defined. To this end, a metric on the effect of simultaneous zooming and panning is defined, based on an estimate of the perceived velocity. Optimal is defined as smooth and efficient. Given the metric, these terms can be translated into a computational model, which is used to calculate an analytic solution for optimal animations. The model has two free parameters: animation speed and zoom/pan trade off. A user experiment to find good values for these is described. | false | false | [
"Jarke J. van Wijk",
"Wim A. A. Nuij"
] | [
"BP"
] | [] | [] |
InfoVis | 2,003 | Thinking with visualization | 10.1109/INFVIS.2003.1249001 | Visualizations help us to solve problems by finding patterns in graphical displays of data. For example, finding a pattern of highly connected components in a node link diagram can help us understand the architecture of a software system. Finding a long, red, fairly straight line on a map can show us the best way of driving between two cities. This talk will describe how thinking with visualizations involves the construction of visual queries on the display. Once a visual query is constructed, a visual search strategy through eye movements and attention to relevant patterns provides answers. Recent results from cognitive psychology can help us understand the visual thinking process. I will show how understanding the nature of visual queries, and the capacity of visual working memory, can be used to predict which visual tasks will be easy and which will be difficult, if not impossible. Examples from common visualizations and interactive techniques will be used to illustrate the central concepts. | false | false | [
"Colin Ware"
] | [] | [] | [] |
InfoVis | 2,003 | Thread Arcs: an email thread visualization | 10.1109/INFVIS.2003.1249028 | This paper describes Thread Arcs, a novel interactive visualization technique designed to help people use threads found in email. Thread Arcs combine the chronology of messages with the branching tree structure of a conversational thread in a mixed-model visualization by Venolia and Neustaedter (2003) that is stable and compact. By quickly scanning and interacting with Thread Arcs, people can see various attributes of conversations and find relevant messages in them easily. We tested this technique against other visualization techniques with users' own email in a functional prototype email client. Thread Arcs proved an excellent match for the types of threads found in users' email for the qualities users wanted in small-scale visualizations. | false | false | [
"Bernard Kerr"
] | [] | [] | [] |
InfoVis | 2,003 | Using multilevel call matrices in large software projects | 10.1109/INFVIS.2003.1249030 | Traditionally, node link diagrams are the prime choice when it comes to visualizing software architectures. However, node link diagrams often fall short when used to visualize large graph structures. In this paper we investigate the use of call matrices as visual aids in the management of large software projects. We argue that call matrices have a number of advantages over traditional node link diagrams when the main object of interest is the link instead of the node. Matrix visualizations can provide stable and crisp layouts of large graphs and are inherently well suited for large multilevel visualizations because of their recursive structure. We discuss a number of visualization issues, using a very large software project currently under development at Philips Medical Systems as a running example. | false | false | [
"Frank van Ham"
] | [] | [] | [] |
InfoVis | 2,003 | Visualization of Labeled Data Using Linear Transformation | 10.1109/INFVIS.2003.1249017 | We present a novel family of data-driven linear transformations, aimed at visualizing multivariate data in a low-dimensional space in a way that optimally preserves the structure of the data. The well-studied PCA and Fisher's LDA (linear discriminant analysis) are shown to be special members in this family of transformations, and we demonstrate how to generalize these two methods such as to enhance their performance. Furthermore, our technique is the only one, to the best of our knowledge, that reflects in the resulting embedding both the data coordinates and pairwise similarities and/or dissimilarities between the data elements. Even more so, when information on the clustering (labeling) decomposition of the data is known, this information can be integrated in the linear transformation, resulting in embeddings that clearly show the separation between the clusters, as well as their infrastructure. All this makes our technique very flexible and powerful, and lets us cope with kinds of data that other techniques fail to describe properly. | false | false | [
"Yehuda Koren",
"Liran Carmel"
] | [] | [] | [] |
InfoVis | 2,003 | Visualization of large-scale customer satisfaction surveys using a parallel coordinate tree | 10.1109/INFVIS.2003.1249026 | Satisfaction surveys are an important measurement tool in fields such as market research or human resources management. Serious studies consist of numerous questions and contain answers from large population samples. Aggregation on both sides, the questions asked as well as the answers received, turns the multidimensional problem into a complex system of interleaved hierarchies. Traditional ways of presenting the results are limited to one-dimensional charts and cross-tables. We developed a visualization method called the Parallel Coordinate Tree that combines multidimensional analysis with a tree structure representation. Distortion-oriented focus+context techniques are used to facilitate interaction with the visualization. In this paper we present a design study of a commercial application that we built, using this method to analyze and communicate results from large-scale customer satisfaction surveys. | false | false | [
"Dominique Brodbeck",
"Luc Girardin"
] | [] | [] | [] |
InfoVis | 2,003 | Visualizing evolving networks: minimum spanning trees versus pathfinder networks | 10.1109/INFVIS.2003.1249010 | Network evolution is an ubiquitous phenomenon in a wide variety of complex systems. There is an increasing interest in statistically modeling the evolution of complex networks such as small-world networks and scale-free networks. In this article, we address a practical issue concerning the visualizations of co-citation networks of scientific publications derived by two widely known link reduction algorithms, namely minimum spanning trees (MSTs) and pathfinder networks (PFNETs). Our primary goal is to identify the strengths and weaknesses of the two methods in fulfilling the need for visualizing evolving networks. Two criteria are derived for assessing visualizations of evolving networks in terms of topological properties and dynamical properties. We examine the animated visualization models of the evolution of botulinum toxin research in terms of its co-citation structure across a 58-year span (1945-2002). The results suggest that although high-degree nodes dominate the structure of MST models, such structures can be inadequate in depicting the essence of how the network evolves because MST removes potentially significant links from high-order shortest paths. In contrast, PFNET models clearly demonstrate their superiority in maintaining the cohesiveness of some of the most pivotal paths, which in turn make the growth animation more predictable and interpretable. We suggest that the design of visualization and modeling tools for network evolution should take the cohesiveness of critical paths into account. | false | false | [
"Chaomei Chen",
"Steven A. Morris"
] | [] | [] | [] |
EuroVis | 2,003 | A Robust Level-Set Algorithm for Centerline Extraction | 10.2312/VisSym/VisSym03/185-194 | We present a robust method for extracting 3D centerlines from volumetric datasets. We start from a 2D skeletonization method to locate voxels centered with respect to three orthogonal slicing directions. Next, we introduce a new detection criterion to extract the centerline voxels from the above skeletons, followed by a thinning, reconnection, and a ranking step. Overall, the proposed method produces centerlines that are object-centered, connected, one voxel thick, robust with respect to object noisiness, handles arbitrary object topologies, comes with a simple pruning threshold, and is fast to compute. We compare our results with two other methods on a variety of real-world datasets. | false | false | [
"Alexandru C. Telea",
"Anna Vilanova"
] | [] | [] | [] |
EuroVis | 2,003 | Accelerated Force Computation for Physics-Based Information Visualization | 10.2312/VisSym/VisSym03/059-066 | Visualization of similarity is an emerging technique for analyzing relation-based data sets. A common way of computing the respective layouts in an information space is to employ a physics-based mass-spring system. Force computation, however, is costly and of order N2. In this paper, we propose a new acceleration method to adopt a well-known optimized force-computation algorithm which drastically reduces the computation time to the order of N log N. The basic idea is to derive a two-pass, "prediction and correction" procedure including a customized potential function. We have applied this method to two different applications: web access and sales analysis. Both demonstrate the efficiency and versatility of the presented method. | false | false | [
"Ming C. Hao",
"Umeshwar Dayal",
"Daniel Cotting",
"Thomas Holenstein",
"Markus H. Gross"
] | [] | [] | [] |
EuroVis | 2,003 | Adaptive Smooth Scattered Data Approximation for Large-scale Terrain Visualization | 10.2312/VisSym/VisSym03/177-184 | We present a fast method that adaptively approximates large-scale functional scattered data sets with hierarchical B-splines. The scheme is memory efficient, easy to implement and produces smooth surfaces. It combines adaptive clustering based on quadtrees with piecewise polynomial least squares approximations. The resulting surface components are locally approximated by a smooth B-spline surface obtained by knot removal. Residuals are computed with respect to this surface approximation, determining the clusters that need to be recursively refined, in order to satisfy a prescribed error bound. We provide numerical results for two terrain data sets, demonstrating that our algorithm works efficiently and accurate for large data sets with highly non-uniform sampling densities. | false | false | [
"Martin Bertram 0001",
"Xavier Tricoche",
"Hans Hagen"
] | [] | [] | [] |
EuroVis | 2,003 | Analysis of HDAF for Interpolation and Noise Suppression in Volume Rendering | 10.2312/VisSym/VisSym03/095-104 | In this paper, we evaluate the HDAF (Hermite Distributed Approximating Functionals) family of interpolation and derivative functions, with respect to their accuracy for reliable volume rendering, and compare them with other interpolation and derivative estimation filters. We utilize several different evaluation methods, both analytical and experimental. The former includes the order of decay of the global error, the local spatial error, and the behavior of the filters in the frequency domain. In the experimental part, visualizations of both synthetic and medical data are produced and studied. We show that the HDAFs exhibit superior behavior if the volumetric data are distorted by high frequency noise, and perform well under noise free conditions. This due to their ability to adjust the range of recovered frequencies. | false | false | [
"K. Anderson",
"Ioannis A. Kakadiaris",
"Manos Papadakis",
"Donald J. Kouri",
"David K. Hoffman"
] | [] | [] | [] |
EuroVis | 2,003 | Anti-Aliased Volume Extraction | 10.2312/VisSym/VisSym03/113-122 | We present a technique to extract regions from a volumetric dataset without introducing any aliasing so that the extracted volume can be explored using direct volume rendering techniques. Extracting regions using binary masks generated by contemporary segmentation approaches typically introduces aliasing at the boundary of the extracted regions. This aliasing is especially visible when the dataset is visualized using direct volume rendering. Our algorithm uses the binary mask only to locate the boundary. The main idea of the algorithm is to retain the natural fuzziness at the boundary of a region even after it is extracted. To achieve that, intensities of the boundary voxels are flipped so that they are now representing a fuzzy boundary with the empty region surrounding it, while preserving the boundary position. | false | false | [
"Sarang Lakare",
"Arie E. Kaufman"
] | [] | [] | [] |
EuroVis | 2,003 | Case Study: Cellar Scaffold Extraction Using Crest Point for Volume Rendering | 10.2312/VisSym/VisSym03/123-128 | null | false | false | [
"Jiuxiang Hu",
"D. Page Baluch",
"Anshuman Razdan",
"Gregory M. Nielson",
"Gerald E. Farin",
"David G. Capco"
] | [] | [] | [] |
EuroVis | 2,003 | Case Study: Comparing Two Methods for Filtering External Motion in 4D Confocal Microscopy Data | 10.2312/VisSym/VisSym03/129-134 | null | false | false | [
"Wim C. de Leeuw",
"Robert van Liere"
] | [] | [] | [] |
EuroVis | 2,003 | Contouring Curved Quadratic Elements | 10.2312/VisSym/VisSym03/167-176 | We show how to extract a contour line (or isosurface) from quadratic elements---specifically from quadratic triangles and tetrahedra. We also devise how to transform the resulting contour line (or surface) into a quartic curve (or surface) based on a curved-triangle (curved-tetrahedron) mapping. A contour in a bivariate quadratic function defined over a triangle in parameter space is a conic section and can be represented by a rational-quadratic function, while in physical space it is a rational quartic. An isosurface in the trivariate case is represented as a rational-quadratic patch in parameter space and a rational-quartic patch in physical space. The resulting contour surfaces can be rendered efficiently in hardware. | false | false | [
"David F. Wiley",
"Henry R. Childs",
"Benjamin F. Gregorski",
"Bernd Hamann",
"Kenneth I. Joy"
] | [] | [] | [] |
EuroVis | 2,003 | Detecting Critical Regions in Scalar Fields | 10.2312/VisSym/VisSym03/085-094 | Trivariate data is commonly visualized using isosurfaces or direct volume rendering. When exploring scalar fields by isosurface extraction it is often difficult to choose isovalues that convey "useful" information. The significance of visualizations using direct volume rendering depends on the choice of good transfer functions. Understanding and using isosurface topology can help in identifying "relevant" isovalues for visualization via isosurfaces and can be used to automatically generate transfer functions.Critical isovalues indicate changes in topology of an isosurface: the creation of new surface components, merging of surface components or the formation of holes in a surface component. Interesting isosurface behavior is likely to occur at and around critical isovalues. Current approaches to detect critical isovalues are usually limited to isolated critical points. Data sets often contain regions of constant value (i.e., mesh edges, mesh faces, or entire mesh cells). We present a method that detects critical points, critical regions and corresponding critical isovalues for a scalar field defined by piecewise trilinear interpolation over a uniform rectilinear grid. We describe how to use the resulting list of critical regions/points and associated values to examine trivariate data. | false | false | [
"Gunther H. Weber",
"Gerik Scheuermann",
"Bernd Hamann"
] | [] | [] | [] |
EuroVis | 2,003 | Detection of constrictions on closed polyhedral surfaces | 10.2312/VisSym/VisSym03/067-074 | We define constrictions on a surface as simple closed geodesic curves, i.e. curves whose length is locally minimal. They can be of great interests in order to cut the surface in smaller parts. In this paper, we present a method to detect constrictions on closed triangulated surfaces. Our algorithm is based on a progressive approach. First, the surface is simplified by repeated edge collapses. The simplification continues until we detect an edge whose collapse would change the topology of the surface. It happens when three edges of the surface form a triangle that does not belong to the surface. The three edges define what we call a seed curve and are used to initialize the search of a constriction. Secondly, the constriction is progressively constructed by incrementally refining the simplified surface until the initial surface is retrieved. At each step of this refinement process, the constriction is updated. Some experimental results are provided. | false | false | [
"Franck Hétroy",
"Dominique Attali"
] | [] | [] | [] |
EuroVis | 2,003 | Efficient Visualization of Large Medical Image Datasets on Standard PC Hardware | 10.2312/VisSym/VisSym03/135-140 | Fast and accurate algorithms for medical image processing and visualization are becoming increasingly important due to routine acquisition and processing of rapidly growing amounts of data in clinical practice. At the same time, standard computer hardware is becoming sufficiently powerful to be used in applications which previously required expensive and inflexible special-purpose hardware. We present an efficient volume rendering approach using the example of maximum intensity projection (MIP), which is an important clinical tool. The method systematically exploits the properties of general-purpose hardware such as hierarchical cache memories and super-scalar processing. In order to optimize the cache efficiency, the dataset is processed in blocks which fit into the processor cache. The innermost ray casting loop is transformed such that the arithmetic operations and memory accesses can be processed in parallel on current general-purpose processors. Combined with other optimization strategies, such as vectorization and block-wise ray skipping, this approach yields near-interactive frame rates for large clinical datasets using a standard dual-processor PC. Data compression and simplification methods have intentionally not been used in order to demonstrate the achievable performance without any quality reductions. Some of the presented ideas can be applied to other computationally intensive image processing tasks. | false | false | [
"Vladimir Pekar",
"Daniel Hempel",
"Gundolf Kiefer",
"Marc Busch",
"Jürgen Weese"
] | [] | [] | [] |
EuroVis | 2,003 | Feature Flow Fields | 10.2312/VisSym/VisSym03/141-148 | Feature tracking algorithms for instationary vector fields are usually based on a correspondence analysis of the features at different time steps. This paper introduces a method for feature tracking which is based on the integration of stream lines of a certain vector field called feature flow field. We analyze for which features the method of feature flow fields can be applied, we show how events in the flow can be detected using feature flow fields, and we show how to construct the feature flow fields for particular classes of features. Finally, we apply the technique to track critical points in a 2D instationary vector field. | false | false | [
"Holger Theisel",
"Hans-Peter Seidel"
] | [] | [] | [] |
EuroVis | 2,003 | Hardware-assisted View-dependent Isosurface Extraction using Spherical Partition | 10.2312/VisSym/VisSym03/267-276 | Extracting only the visible portion of an isosurface can improve both the computation efficiency and the rendering speed. However, the visibility test overhead can be quite high for large scale data sets. In this paper, we present a view-dependent isosurface extraction algorithm utilizing occlusion query hardware to accelerate visible isosurface extraction. A spherical partition scheme is proposed to traverse the data blocks in a layered front-to-back order. Such traversal order helps our algorithm to identify the visible isosurface blocks more quickly with fewer visibility queries. Our algorithm can compute a more complete isosurface in a smaller amount of time, and thus is suitable for time-critical visualization applications. | false | false | [
"Jinzhu Gao",
"Han-Wei Shen"
] | [] | [] | [] |
EuroVis | 2,003 | Hierarchical Isosurface Segmentation Based on Discrete Curvature | 10.2312/VisSym/VisSym03/249-258 | A high-level approach to describe the characteristics of a surface is to segment it into regions of uniform curvature behavior and construct an abstract representation given by a (topology) graph. We propose a surface segmentation method based on discrete mean and Gaussian curvature estimates. The surfaces are obtained from three-dimensional imaging data sets by isosurface extraction after data presmoothing and postprocessing the isosurfaces by a surface-growing algorithm. We generate a hierarchical multiresolution representation of the isosurface. Segmentation and graph generation algorithms can be performed at various levels of detail. At a coarse level of detail, the algorithm detects the main features of the surface. This low-resolution description is used to determine constraints for the segmentation and graph generation at the higher resolutions. We have applied our methods to MRI data sets of human brains. The hierarchical segmentation framework can be used for brain-mapping purposes. | false | false | [
"Fabien Vivodtzev",
"Lars Linsen",
"Georges-Pierre Bonneau",
"Bernd Hamann",
"Kenneth I. Joy",
"Bruno A. Olshausen"
] | [] | [] | [] |
EuroVis | 2,003 | Improving Topological Segmentation of Three-dimensional Vector Fields | 10.2312/VisSym/VisSym03/203-212 | We present three enhancements to accelerate the extraction of separatrices of three-dimensional vector fields, using intelligently selected "sample" streamlines. These enhancements reduce the number of needed sample streamlines and their propagation length. Inflow/outflow matching supports the simultaneous extraction of topologically significant inflow and outflow separatrices in a single pass. An adaptive sampling approach is introduced and used to seed streamlines in a more meaningful and efficient manner. Cell-locking is a new concept that isolates regions of a data set that do not contain separatrices. This concept makes streamline propagation more efficient as streamlines are not propagated through cells that do not influence or contain separatrices. These enhancements enable us to perform separatrix construction for three-dimensional vector field data requiring less overall computation. | false | false | [
"Karim Mahrous",
"Janine Bennett",
"Bernd Hamann",
"Kenneth I. Joy"
] | [] | [] | [] |
EuroVis | 2,003 | Interaction of Light and Tensor Fields | 10.2312/VisSym/VisSym03/157-166 | We present three new ways of looking at tensor volumes. All three methods are based on the interaction of simulated light and the tensor field. Conceptually, rays are shot from a certain direction into the tensor volume. These rays are influenced by the surrounding tensor field and bent as they traverse through the volume. The tensor is visualized by both the nature of the bent rays and by the collection of rays deposited on a receiving plate. The former is similar to streamlines, but shows paths of greatest influence by the tensor field. The latter is similar to caustic effects from photon maps, but shows the convergence or divergence of the rays through the tensor volume. We also use the concept of treating the tensor volume as a special lens that distorts an image. Using backward ray tracing through the tensor volume, we generate image distortions that also show internal properties of the tensor field. A key advantage of these techniques is that they can work directly with non-symmetric tensor fields without first decomposing them into components. Color images can also be found in www.soe.ucsc.edu/research/avis/tensorray.html. | false | false | [
"Xiaoqiang Zheng",
"Alex Pang"
] | [] | [] | [] |
EuroVis | 2,003 | Interactive Feature Specification for Focus+Context Visualization of Complex Simulation Data | 10.2312/VisSym/VisSym03/239-248 | Visualization of high-dimensional, large data sets, resulting from computational simulation, is one of the most challenging fields in scientific viualization. When visualization aims at supporting the analysis of such data sets, feature-based approches are very useful to reduce the amount of data which is shown at each instance of time and guide the user to the most interesting areas of the data. When using feature-based visualization, one of the most difficult questions is how to extract or specify the features. This is mostly done (semi-)automatic up to now. Especially when interactive analysis of the data is the main goal of the visualization, tools supporting interactive specification of features are needed.In this paper we present a framework for fiexible and interactive specification of high-dimensional and/or complex features in simulation data. The framework makes use of multiple, linked views from information as well as scienti c visualization and is based on a simple and compact feature definition language (FDL). It allows the definition of one or several features, which can be complex and/or hierarchically described by brushing multiple dimensions (using non-binary and composite brushes). The result of the specification is linked to all views, thereby a focus+context style of visualization in 3D is realized. To demonstrate the usage of the specification, as well as the linked tools, applications from flow simulation in the automotive industry are presented. | false | false | [
"Helmut Doleisch",
"Martin Gasser",
"Helwig Hauser"
] | [] | [] | [] |
EuroVis | 2,003 | ISOSLIDER: A System for Interactive Exploration of Isosurfaces | 10.2312/VisSym/VisSym03/259-266 | We present ISOSLIDER, a system for interactive exploration of isosurfaces of a scalar field. Our algorithm focuses on fast update of isosurfaces for interactive display as a user makes small changes to the isovalue of the desired surface. We exploit the coherence of this update. Larger changes are supported as well. The update to the isosurface is made at a correct level of detail so that not too many operations need be performed nor too many triangles need be rendered. ISOSLIDER does not need to retain the entire volume in the main memory and stores most data out of core. The central idea of the ISOSLIDER algorithm is to determine salient isovalues where surface topology changes and pre-encode these changes so as to facilitate fast updates to the triangulation. | false | false | [
"Jatin Chhugani",
"Sudhir Vishwanath",
"Jonathan D. Cohen 0001",
"Subodh Kumar 0001"
] | [] | [] | [] |
EuroVis | 2,003 | Isosurfaces on Optimal Regular Samples | 10.2312/VisSym/VisSym03/039-048 | Volumetric samples on Cartesian lattices are less efficient than samples on body-centred cubic (BCC) lattices. We show how to construct isosurfaces on BCC lattices using several different algorithms. Since the mesh that arises from BCC lattices involves a large number of cells, we show two alternate methods of reducing the number of cells by clumping tetrahedra into either octahedra or hexahedra. We also propose a theoretical model for estimating triangle counts for various algorithms, and present experimental results to show that isosurfaces generated using one of our algorithms can be competitive with isosurfaces generated using Marching Cubes on similar Cartesian grids. | false | false | [
"Hamish A. Carr",
"Thomas Theußl",
"Torsten Möller"
] | [] | [] | [] |
EuroVis | 2,003 | MCMR: A Fluid View on Time Dependent Volume Data | 10.2312/VisSym/VisSym03/149-156 | Mass Conservative Motion Reconstruction is a new method for estimating motion in time dependent volume data. A time dependent vector field representing the movement of the data is computed from a sequence of scalar volume data sets. The principle of mass conservation in a continuum is used during the reconstruction. Standard fiow visualization techniques are used for the visualization of the derived vector field.This paper presents the underlying concepts of MCMR, its implementation, its accuracy and applicability. | false | false | [
"Wim C. de Leeuw",
"Robert van Liere"
] | [] | [] | [] |
EuroVis | 2,003 | Path Seeds and Flexible Isosurfaces - Using Topology for Exploratory Visualization | 10.2312/VisSym/VisSym03/049-058 | Morse theory and the Reeb graph give topological summaries of the behaviour of continuous scalar functions. The contour tree augments the Reeb graph for the isosurfaces in a volume to store seed sets, which are starting points for extracting isosurfaces by the continuation method. We replace the minimal seed sets of van Kreveld et al. with path seeds, which generate paths that correspond directly to the individual components of an isosurface. From a path we get exactly one seed per component, which reduces storage and simplifies isosurface extraction. Moreover, the correspondence allows us to extend the contour spectrum of Bajaj et al. to an interface that we call flexible isosurfaces, in which individual contours with different isovalues can be displayed, manipulated and annotated. The largest contour segmentation, in which separate surfaces are generated for each local maximum of the field, is a special case of the flexible isosurface. | false | false | [
"Hamish A. Carr",
"Jack Snoeyink"
] | [] | [] | [] |
EuroVis | 2,003 | Post-convolved Splatting | 10.2312/VisSym/VisSym03/223-230 | One of the most expensive operations in volume rendering is the interpolation of samples in volume space. The number of samples, in turn, depends on the resolution of the final image. Hence, viewing the volume at high magnification will incur heavy computation. In this paper, we explore an approach that limits the number of samples to the resolution of the volume, independent of the magnification factor, using a cheap post-convolution process on the interpolated samples to generate the missing samples. For X-ray, this post-convolution is needed only once, after the volume is fully projected, while in full volume rendering, the post-convolution must be applied before each shading and compositing step. Using this technique, we are able to achieve speedups of two and more, without compromising rendering quality. We demonstrate our approach using an image-aligned sheet-buffered splatting algorithm, but our conclusions readily generalize to any volume rendering algorithm that advances across the volume in a slice-based fashion. | false | false | [
"Neophytos Neophytou",
"Klaus Mueller 0001"
] | [] | [] | [] |
EuroVis | 2,003 | Rendering Vector Data over Global, Multiresolution 3D Terrain | 10.2312/VisSym/VisSym03/213-222 | Modern desktop PCs are capable of taking 2D Geographic Information System (GIS) applications into the realm of interactive 3D virtual worlds. In prior work we developed and presented graphics algorithms and data management methods for interactive viewing of a 3D global terrain system for desktop and virtual reality systems. In this paper we present a key data structure and associated render-time algorithm for the combined display of multi-resolution 3D terrain and traditional GIS polyline vector data. Such vector data is traditionally used for representing geographic entities such as political borders, roads, rivers and cadastral information. | false | false | [
"Zachary Wartell",
"Eunjung Kang",
"Tony Wasilewski",
"William Ribarsky",
"Nickolas Faust"
] | [] | [] | [] |
EuroVis | 2,003 | ShellSplatting: Interactive Rendering of Anisotropic Volumes | 10.2312/VisSym/VisSym03/105-112 | This work presents an extension of shell rendering that is moreflexible and yields higher quality volume renderings. Shell rendering consists of efficient data-structures and methods to manipulate and render structures with non-precise boundaries in volume data. We have updated these algorithms by creating an implementation that makes effective use of ubiquitously available commercial graphics hardware. More significantly, we have extended the algorithm to make use of elliptical Gaussian splats instead of straight-forward voxel projection. This dramatically increases the quality of the renderings, especially with anisotropically sampled volumes. The use of the graphics hardware alleviates the performance penalty of using splats. | false | false | [
"Charl P. Botha",
"Frits H. Post"
] | [] | [] | [] |
EuroVis | 2,003 | Shrouds: Optimal Separating Surfaces for Enumerated Volumes | 10.2312/VisSym/VisSym03/075-084 | We describe new techniques for computing a smooth triangular mesh surface that surrounds an enumerated volume consisting of a collection of points from a 3D rectilinear grid. The surface has the topology of an isosurface computed by a marching cubes method applied to a field function that has the value one at the points in the volume and zero for points not in the volume. The vertices are confined to the edges of the grid that penetrate this separating surface and the precise positions are computed so as to optimize a certain energy functional applied to the surface. We use efficient iterative methods to compute the optimal separating surfaces. We lift the concept of energy functionals for planar curves to isosurfaces by means of the 4*-network which is a unique collection of orthogonal planar polygons lying on the isosurface. The general strategy that we describe here leads to methods that are simple, efficient, and effective. | false | false | [
"Gregory M. Nielson",
"Gary Graf",
"Ryan Holmes",
"Adam Huang",
"Mariano Phielipp"
] | [] | [] | [] |
EuroVis | 2,003 | Smart Hardware-Accelerated Volume Rendering | 10.2312/VisSym/VisSym03/231-238 | For volume rendering of regular grids the display of view-plane aligned slices has proven to yield both good quality and performance. In this paper we demonstrate how to merge the most important extensions of the original 3D slicing approach, namely the pre-integration technique, volumetric clipping, and advanced lighting. Our approach allows the suppression of clipping artifacts and achieves high quality while offering the fiexibility to explore volume data sets interactively with arbitrary clip objects. We also outline how to utilize the proposed volumetric clipping approach for the display of segmented data sets. Moreover, we increase the rendering quality by implementing efficient over-sampling with the pixel shader of consumer graphics accelerators. We give prove that at least 4-times over-sampling is needed to reconstruct the ray integral with sufficient accuracy even with pre-integration. As an alternative to this brute-force over-sampling approach we propose a hardware-accelerated ray caster which is able to perform over-sampling only where needed and which is able to gain additional speed by early ray termination and space leaping. | false | false | [
"Stefan Röttger",
"Stefan Guthe",
"Daniel Weiskopf",
"Thomas Ertl",
"Wolfgang Straßer"
] | [] | [] | [] |
EuroVis | 2,003 | Using Graphs for Fast Error Term Approximation of Time-varying Datasets | 10.2312/VisSym/VisSym03/009-018 | We present a method for the efficient computation and storage of approximations of error tables used for error estimation of a region between different time steps in time-varying datasets. The error between two time steps is defined as the distance between the data of these time steps. Error tables are used to look up the error between different time steps of a time-varying dataset, especially when run time error computation is expensive. However, even the generation of error tables itself can be expensive. For n time steps, the exact error look-up table (which stores the error values for all pairs of time steps in a matrix) has a memory complexity and pre-processing time complexity of O(n2), and O(1) for error retrieval.Our approximate error look-up table approach uses trees, where the leaf nodes represent original time steps, and interior nodes contain an average (or best-representative) of the children nodes. The error computed on an edge of a tree describes the distance between the two nodes on that edge. Evaluating the error between two different time steps requires traversing a path between the two leaf nodes, and accumulating the errors on the traversed edges. For n time steps, this scheme has a memory complexity and pre-processing time complexity of O(n log(n)), a significant improvement over the exact scheme; the error retrieval complexity is O(log(n)). As we do not need to calculate all possible n2 error terms, our approach is a fast way to generate the approximation. | false | false | [
"Christof Nuber",
"Eric LaMar",
"Valerio Pascucci",
"Bernd Hamann",
"Kenneth I. Joy"
] | [] | [] | [] |
EuroVis | 2,003 | Vector field visualization using Markov Random Field texture synthesis | 10.2312/VisSym/VisSym03/195-202 | Vector field visualization aims at generating images in order to convey the information existing in the data. We use Markov Random Field (MRF) texture synthesis methods to generate the visualization from a set of sample textures. MRF texture synthesis methods allow generating images that are locally similar to a given example image. We extend this idea for vector field visualization by identifying each vector value with a representative example image, e.g. a strongly directed texture that is rotated according to a 2D vector. The visualization is synthesized pixel by pixel, where each pixel is chosen from the sample texture according to the vector values of the local pixel. The visualization locally communicates the vector information as each pixel is chosen from a sample that is representative of the vector. Furthermore it is smooth, as MRF texture synthesis searches for best fitting neighborhoods. This leads to dense and smooth visualizations with the additional freedom to use arbitrary representation textures for any vector value. | false | false | [
"Francesca Taponecco",
"Marc Alexa"
] | [] | [] | [] |
EuroVis | 2,003 | Visual Hierarchical Dimension Reduction for Exploration of High Dimensional Datasets | 10.2312/VisSym/VisSym03/019-028 | Traditional visualization techniques for multidimensional data sets, such as parallel coordinates, glyphs, and scatterplot matrices, do not scale well to high numbers of dimensions. A common approach to solving this problem is dimensionality reduction. Existing dimensionality reduction techniques usually generate lower dimensional spaces that have little intuitive meaning to users and allow little user interaction. In this paper we propose a new approach to handling high dimensional data, named Visual Hierarchical Dimension Reduction (VHDR), that addresses these drawbacks. VHDR not only generates lower dimensional spaces that are meaningful to users, but also allows user interactions in most steps of the process. In VHDR, dimensions are grouped into a hierarchy, and lower dimensional spaces are constructed using clusters of the hierarchy. We have implemented the VHDR approach into XmdvTool, and extended several traditional multidimensional visualization methods to convey dimension cluster characteristics when visualizing the data set in lower dimensional spaces. Our case study of applying VHDR to a real data set supports our belief that this approach is effective in supporting the exploration of high dimensional data sets. | false | false | [
"Jing Yang 0001",
"Matthew O. Ward",
"Elke A. Rundensteiner",
"Shiping Huang"
] | [] | [] | [] |
EuroVis | 2,003 | Visualizing Spatial Distribution Data Sets | 10.2312/VisSym/VisSym03/029-038 | null | false | false | [
"Alison Luo",
"David L. Kao",
"Jennifer L. Dungan",
"Alex Pang"
] | [] | [] | [] |
CHI | 2,003 | Designing novel interactional workspaces to support face to face consultations | 10.1145/642611.642623 | This paper describes the design and deployment of a novel interactional workspace, intended to provide more effective support for face-to-face consultations between two parties. We focus on the initial consultations between customer and agent that take place during the development of complex products. Findings from an ethnographic study of the existing use of technological systems show the interaction during such consultations to be disjointed and not well supported. As an alternative approach, we developed a novel arrangement of multiple displays intended to promote shoulder-to-shoulder collaboration using a variety of interlinked representations and visualizations. The resulting interactional workspace was used by a travel company as part of a large international trade show attended by the general public. The many consultations that took place between agents and customers were quite different, proving to be more equitable, open, fluid and congenial. | false | false | [
"Tom Rodden",
"Yvonne Rogers",
"John Halloran 0001",
"Ian Taylor"
] | [] | [] | [] |
CHI | 2,003 | Halo: a technique for visualizing off-screen objects | 10.1145/642611.642695 | As users pan and zoom, display content can disappear into off-screen space, particularly on small-screen devices. The clipping of locations, such as relevant places on a map, can make spatial cognition tasks harder. Halo is a visualization technique that supports spatial cognition by showing users the location of off-screen objects. Halo accomplishes this by surrounding off-screen objects with rings that are just large enough to reach into the border region of the display window. From the portion of the ring that is visible on-screen, users can infer the off-screen location of the object at the center of the ring. We report the results of a user study comparing Halo with an arrow-based visualization technique with respect to four types of map-based route planning tasks. When using the Halo interface, users completed tasks 16-33% faster, while there were no significant differences in error rate for three out of four tasks in our study. | false | false | [
"Patrick Baudisch",
"Ruth Rosenholtz"
] | [] | [] | [] |
CHI | 2,003 | Recommending collaboration with social networks: a comparative evaluation | 10.1145/642611.642714 | Studies of information seeking and workplace collaboration often find that social relationships are a strong factor in determining who collaborates with whom. Social networks provide one means of visualizing existing and potential interaction in organizational settings. Groupware designers are using social networks to make systems more sensitive to social situations and guide users toward effective collaborations. Yet, the implications of embedding social networks in systems have not been systematically studied. This paper details an evaluation of two different social networks used in a system to recommend individuals for possible collaboration. The system matches people looking for expertise with individuals likely to have expertise. The effectiveness of social networks for matching individuals is evaluated and compared. One finding is that social networks embedded into systems do not match individuals' perceptions of their personal social network. This finding and others raise issues for the use of social networks in groupware. Based on the evaluation results, several design considerations are discussed. | false | false | [
"David W. McDonald"
] | [] | [] | [] |
CHI | 2,003 | Understanding sequence and reply relationships within email conversations: a mixed-model visualization | 10.1145/642611.642674 | It has been proposed that email clients could be improved if they presented messages grouped into conversations. An email conversation is the tree of related messages that arises from the use of the reply operation. We propose two models of conversation. The first model characterizes a conversation as a chronological sequence of messages; the second as a tree based on the reply relationship. We show how existing email clients and prior research projects implicitly support each model to a greater or lesser degree depending on their design, but none fully supports both models simultaneously. We present a mixed-model visualization that simultaneously presents sequence and reply relationships among the messages of a conversation, making both visible at a glance. We describe the integration of the visualization into a working prototype email client. A usability study indicates that the system meets our usability goals and verifies that the visualization fully conveys both types of relationships within the messages of an email conversation. | false | false | [
"Gina Danielle Venolia",
"Carman Neustaedter"
] | [] | [] | [] |
Vis | 2,002 | A case study in selective visualization of unsteady 3D flow | 10.1109/VISUAL.2002.1183821 | In this case study, we explore techniques for the purpose of visualizing isolated flow structures in time-dependent data. Our primary industrial application is the visualization of the vortex rope, a rotating helical structure which builds up in the draft tube of a water turbine. The vortex rope can be characterized by high values of normalized helicity, which is a scalar field derived from the given CFD velocity data. In two related applications, the goal is to visualize the cavitation regions near the runner blades of a Kaplan turbine and a water pump, respectively. Again, the flow structure of interest can be defined by a scalar field, namely by low pressure values. We propose a particle seeding scheme based on quasi-random numbers, which minimizes visual artifacts such as clusters or patterns. By constraining the visualization to a region of interest, occlusion problems are reduced and storage efficiency is gained. | false | false | [
"Dirk Bauer",
"Ronald Peikert",
"Mie Sato",
"Mirjam Sick"
] | [] | [] | [] |
Vis | 2,002 | A case study on automatic camera placement and motion for visualizing historical data | 10.1109/VISUAL.2002.1183826 | In this paper, we address the problem of automatic camera positioning and automatic camera path generation in the context of historical data visualization. After short description of the given data, we elaborate on the constraints for the positioning of a virtual camera in such a way that not only the projected area is maximized, but also the depth of the displayed scene. This is especially important when displaying terrain models, which do not provide good 3D impression when only the projected area is maximized. Based on this concept, we present a method for computing an optimal camera position for each instant of time. Since the explored data are not static, but change depending on the explored scene time, we also discuss a method for animation generation. In order to avoid sudden changes of the camera position, when the previous method is applied for each frame (point in time), we introduce pseudo-events in time, which expand the bounding box defined by the currently active events of interest. In particular, this technique allows events happening in a future point in time to be taken into account such that when this time becomes current, all events of interest are already within the current viewing frustum of the camera. | false | false | [
"Stanislav L. Stoev",
"Wolfgang Straßer"
] | [] | [] | [] |
Vis | 2,002 | A case study on multiresolution visualization of local rainfall from weather radar measurements | 10.1109/VISUAL.2002.1183823 | Weather radars can measure the backscatter from rain drops in the atmosphere. A complete radar scan provides three-dimensional precipitation information. For the understanding of the underlying atmospheric processes interactive visualization of these data sets is necessary. This is a challenging task due to the size, structure and required context of the data. In this case study, a multiresolution approach for real-time simultaneous visualization of radar measurements together with the corresponding terrain data is illustrated. | false | false | [
"Thomas Gerstner",
"Dirk Meetschen",
"Susanne Crewell",
"Michael Griebel",
"Clemens Simmer"
] | [] | [] | [] |
Vis | 2,002 | A case study on the applications of a generic library for low-cost polychromatic passive stereo | 10.1109/VISUAL.2002.1183829 | Active stereo has been used by engineers and industrial designers for several years to enhance the perception of computer generated three-dimensional images. Unfortunately, active stereo requires specialized hardware. Therefore, as ubiquitous computing and teleworking gain importance, using active stereo becomes a problem. The goal of this case study is to examine the concept of a generic library for polychromatic passive stereo to make stereo vision available everywhere. | false | false | [
"Simon Stegmaier",
"Dirc Rose",
"Thomas Ertl"
] | [] | [] | [] |
Vis | 2,002 | A model for the visualization exploration process | 10.1109/VISUAL.2002.1183791 | The current state of the art in visualization research places strong emphasis on different techniques to derive insight from disparate types of data. However, little work has investigated the visualization process itself. The information content of the visualization process - the results, history, and relationships between those results - is addressed by this work. A characterization of the visualization process is discussed, leading to a general model of the visualization exploration process. The model, based upon a new parameter derivation calculus, can be used for automated reporting, analysis, or visualized directly. An XML-based language for expressing visualization sessions using the model is also described. These sessions can then be shared and reused by collaborators. The model, along with the XML representation, provides an effective means to utilize information within the visualization process to further data exploration. | false | false | [
"T. J. Jankun-Kelly",
"Kwan-Liu Ma",
"Michael Gertz 0001"
] | [] | [] | [] |
Vis | 2,002 | A multiphase approach to efficient surface simplification | 10.1109/VISUAL.2002.1183765 | We present a new multiphase method for efficiently simplifying polygonal surface models of arbitrary size. It operates by combining an initial out-of-core uniform clustering phase with a subsequent in-core iterative edge contraction phase. These two phases are both driven by quadric error metrics, and quadrics are used to pass information about the original surface between phases. The result is a method that produces approximations of a quality comparable to quadric-based iterative edge contraction, but at a fraction of the cost in terms of running time and memory consumption. | false | false | [
"Michael Garland",
"Eric Shaffer"
] | [] | [] | [] |
Vis | 2,002 | A new object-order ray-casting algorithm | 10.1109/VISUAL.2002.1183776 | 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. | false | false | [
"Benjamin Mora",
"Jean-Pierre Jessel",
"René Caubet"
] | [] | [] | [] |
Vis | 2,002 | A radial focus+context visualization for multi-dimensional functions | 10.1109/VISUAL.2002.1183806 | 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. | false | false | [
"Sanjini Jayaraman",
"Chris North 0001"
] | [] | [] | [] |
Vis | 2,002 | Approximating normals for marching cubes applied to locally supported isosurfaces | 10.1109/VISUAL.2002.1183808 | 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. | false | false | [
"Gregory M. Nielson",
"Adam Huang",
"Steve Sylvester"
] | [] | [] | [] |
Vis | 2,002 | Assisted navigation for large information spaces | 10.1109/VISUAL.2002.1183803 | 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. | false | false | [
"Brent M. Dennis",
"Christopher G. Healey"
] | [] | [] | [] |
Vis | 2,002 | BLIC: Bi-Level Isosurface Compression | 10.1109/VISUAL.2002.1183807 | 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. | false | false | [
"Gabriel Taubin"
] | [] | [] | [] |
Vis | 2,002 | BM3D: motion estimation in time dependent volume data | 10.1109/VISUAL.2002.1183804 | 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. | false | false | [
"Wim C. de Leeuw",
"Robert van Liere"
] | [] | [] | [] |
Vis | 2,002 | Bounded-distortion piecewise mesh parameterization | 10.1109/VISUAL.2002.1183795 | 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. | false | false | [
"Olga Sorkine-Hornung",
"Daniel Cohen-Or",
"Rony Goldenthal",
"Dani Lischinski"
] | [] | [] | [] |
Vis | 2,002 | Case study on the adaptation of interactive visualization applications to Web-based production for operational mesoscale weather models | 10.1109/VISUAL.2002.1183827 | 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. | false | false | [
"Lloyd Treinish"
] | [] | [] | [] |
Vis | 2,002 | Case study: A look of performance expression | 10.1109/VISUAL.2002.1183815 | 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. | false | false | [
"Rumi Hiraga"
] | [] | [] | [] |
Vis | 2,002 | Case study: A virtual environment for genomic data visualization | 10.1109/VISUAL.2002.1183818 | 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. | false | false | [
"R. Mark Adams",
"Blaze Stancampiano",
"Michael McKenna",
"David Small"
] | [] | [] | [] |
Vis | 2,002 | Case study: hardware-accelerated selective LIC volume rendering | 10.1109/VISUAL.2002.1183811 | 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. | false | false | [
"Yasuko Suzuki",
"Issei Fujishiro",
"Li Chen",
"Hiroko Nakamura"
] | [] | [] | [] |
Vis | 2,002 | Case study: Interactive rendering of adaptive mesh refinement data | 10.1109/VISUAL.2002.1183820 | 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. | false | false | [
"Sanghun Park",
"Chandrajit L. Bajaj",
"Vinay Siddavanahalli"
] | [] | [] | [] |
Vis | 2,002 | Case study: Interactive visualization for Internet security | 10.1109/VISUAL.2002.1183816 | 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. | false | false | [
"Soon Tee Teoh",
"Kwan-Liu Ma",
"Shyhtsun Felix Wu",
"Xiaoliang Zhao"
] | [] | [] | [] |
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