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Least square projection: A fast high-precision multidimensional projection technique and its application to document mapping

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IEEE TRANSACTIONS ON visualization AND COMPUTER GRAPHICS 2008年第3期14卷 564-575页

作者： Paulovich, Fernando V. Nonato, Luis Gustavo Minghim, Rosane Levkowitz, Haim Univ Sao Paulo Inst Ciencia Matemat & Computacao BR-13560970 Sao Carlos SP Brazil Univ Massachusetts Dept Comp Sci Lowell MA 01854 USA

The problem of projecting multidimensional data into lower dimensions has been pursued by many researchers due to its potential application to data analyses of various kinds. This paper presents a novel multidimensional projection technique based on least square approximations. The approximations compute the coordinates of a set of projected points based on the coordinates of a reduced number of control points with defined geometry. We name the technique Least Square Projections ( LSP). From an initial projection of the control points, LSP defines the positioning of their neighboring points through a numerical solution that aims at preserving a similarity relationship between the points given by a metric in mD. In order to perform the projection, a small number of distance calculations are necessary, and no repositioning of the points is required to obtain a final solution with satisfactory precision. The results show the capability of the technique to form groups of points by degree of similarity in 2D. We illustrate that capability through its application to mapping collections of textual documents from varied sources, a strategic yet difficult application. LSP is faster and more accurate than other existing high-quality methods, particularly where it was mostly tested, that is, for mapping text sets.

关键词： document and text processing visualization simulation modeling and visualization data and knowledge visualization information visualization visualization techniques and methodologies

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An insight-based methodology for evaluating bioinformatics visualizations

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IEEE TRANSACTIONS ON visualization AND COMPUTER GRAPHICS 2005年第4期11卷 443-456页

作者： Saraiya, P North, C Duca, K Virginia Tech Dept Comp Sci Blacksburg VA 24061 USA Virginia Tech Virginia Bioinformat Inst Blacksburg VA 24061 USA

High-throughput experiments, such as gene expression microarrays in the life sciences, result in very large data sets. In response, a wide variety of visualization tools have been created to facilitate data analysis. A primary purpose of these tools is to provide biologically relevant insight into the data. Typically, visualizations are evaluated in controlled studies that measure user performance on predetermined tasks or using heuristics and expert reviews. To evaluate and rank bioinformatics visualizations based on real-world data analysis scenarios, we developed a more relevant evaluation method that focuses on data insight. This paper presents several characteristics of insight that enabled us to recognize and quantify it in open-ended user tests. Using these characteristics, we evaluated five microarray visualization tools on the amount and types of insight they provide and the time it takes to acquire it. The results of the study guide biologists in selecting a visualization tool based on the type of their microarray data, visualization designers on the key role of user interaction techniques, and evaluators on a new approach for evaluating the effectiveness of visualizations for providing insight. Though we used the method to analyze bioinformatics visualizations, it can be applied to other domains.

关键词： evaluation/methodology graphical user interfaces (GUI) information visualization visualization systems and software visualization techniques and methodologies

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Knowledge precepts for design and evaluation of information visualizations

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IEEE TRANSACTIONS ON visualization AND COMPUTER GRAPHICS 2005年第4期11卷 432-442页

作者： Amar, RA Stasko, JT Georgia Inst Technol Coll Comp GVU Ctr Atlanta GA 30332 USA

The design and evaluation of most current information visualization systems descend from an emphasis on a user's ability to "unpack" the representations of data of interest and operate on them independently. Too often, successful decision-making and analysis are more a matter of serendipity and user experience than of intentional design and specific support for such tasks;although humans have considerable abilities in analyzing relationships from data, the utility of visualizations remains relatively variable across users, data sets, and domains. In this paper, we discuss the notion of analytic gaps, which represent obstacles faced by visualizations in facilitating higher-level analytic tasks, such as decision-making and learning. We discuss support for bridging these gaps, propose a framework for the design and evaluation of information visualization systems, and demonstrate its use.

关键词： information visualization visualization techniques and methodologies theory and methods

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Artifacts caused by simplicial subdivision

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IEEE TRANSACTIONS ON visualization AND COMPUTER GRAPHICS 2006年第2期12卷 231-242页

作者： Carr, H Möller, T Snoeyink, J Univ Coll Dublin Sch Comp Sci & Informat Dublin 4 Ireland Simon Fraser Univ Sch Comp Sci Burnaby BC V5A 1S6 Canada Univ N Carolina Dept Comp Sci Chapel Hill NC 27599 USA

We review schemes for dividing cubic cells into simplices ( tetrahedra) for interpolating from sampled data to IR3, present visual and geometric artifacts generated in isosurfaces and volume renderings, and discuss ho... 详细信息

关键词： interpolation approximation of surfaces and contours image representation volumetric representation visualization techniques and methodologies volume visualization

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A Visual Approach to Improve Clustering Based on Cluster Ensembles

A Visual Approach to Improve Clustering Based on Cluster Ens...

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Conference on visualization and Data Analysis 2010

作者： Zhou, Jianping Konecni, Shawn Marx, Kenneth Grinstein, Georges Univ Massachusetts Lowell Lowell MA 01854 USA

ISBN: (纸本)9780819479235

Iterative clustering (e.g. K-Means, EM) is one of the most commonly used clustering methods, which attempts to iteratively find a local optimum starting from an initial condition, including initial centroids and initial number of clusters. For iterative clustering, research has shown that the initial conditions are crucial to clustering quality and running time of a clustering computation. Using a novel visualization tool, CComViz (Cluster Comparison visualization), we present an innovative approach to refine the initial centroids and the number of clusters by visually analyzing multiple clustering results generated by different clustering algorithms. As an example, we apply our new approach to a gene expression case study for generating a better and converging clustering. The proposed approach is considered to be an extension to cluster ensembles since the original data sources are reused, while in classic cluster ensembles they are not.

关键词： Biology and genetics Classifier design and evaluation Clustering visualization techniques and methodologies

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Multisensory Modeling of Tabular Data for Enhanced Perception and Immersive Experience 18th

Multisensory Modeling of Tabular Data for Enhanced Perceptio...

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18th International Symposium on Visual Computing (ISVC)

作者： Yasmin, Shamima Jamal, Chowdhury Q. Eastern Washington Univ Spokane WA 99202 USA Univ Waterloo Waterloo ON N2L 3G1 Canada

ISBN: (纸本)9783031479656;9783031479663

Multisensory visualization incorporating sight, sound, and touch can substantially enhance user interest and perception compared to unimodal vision-only applications. In a music-enhanced heatmap, color-coded rectangular bars become audibly distinct as they are assigned auditory parameters (i.e., pitch, tempo, and so on) depending on the data range. While navigating with a haptic device, music-enhanced bars in a heatmap would respond with varying audio feedback. Bars can be further assigned tangible properties (i.e., friction or stiffness) depending on variable values. This paper investigates the efficacy of immersive multimodal visualization that considers enhanced user experience. Research findings showed that a multimodal approach is more effective in improving overall user experience and engagement than traditional unimodal vision-based experience. If enhanced with virtual reality (VR), multi-sensory visualization can provide an immersive experience as users interact with and explore large datasets in a life-size environment. In addition, multimodal strategies can create a diverse, accessible, and inclusive environment.

关键词： Multimodal systems Virtual reality Human-computer interaction Haptics Information visualization Multivariate data visualization techniques and methodologies

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A new pixel-oriented visualization technique through color image

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Information visualization 1997年第4期4卷 257-265页

作者： Blanchard, Frédéric Herbin, Michel Lucas, Laurent CReSTIC-LERI EA 3804 University of Reims Champagne-Ardenne Reims Cedex rue des Crayères France

Color image is often considered as a fundamental perceptual unit of visualization. In this paper, we suggest using this medium (color image) to summarize multidimensional data and thus to turn a data set into a meaningful insight. The methodology we use is based on the theory of Keim for designing pixel-oriented visualization techniques. The technique we propose consists in a three-step pipeline. The first one is devoted to dimensionality reduction by projecting multidimensional data into a three-dimensional space. In this work, we use the classical principal component analysis (PCA) to reduce the dimension to three. The second step, called color mapping, is based on the reverse color information transformation defined by Ohta et al. This stage is the main novelty of this work in addition to the pipeline itself. The third step consists in a pixel-oriented method to display large data sets with an image using space-filling curve techniques. The combination of these steps (first, dimensionality reduction with PCA, second, color mapping with color information of Ohta et al., and third, space-filling curve with Peano–Hilbert curve) allows us to obtain a new unsupervised visualization technique through color images. This blind (i.e. unsupervised) technique using a color image gives a previsualization that can be used before exploring the data set or choosing more effective colors. Some applications are proposed in the field of multicomponent image visualization. © 2005, SAGE Publications. All rights reserved.

关键词： color data visualization high-dimensional data sets pixel classification scanning visualization techniques and methodologies

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An insight-based methodology for evaluating bioinformatics visualizations

An insight-based methodology for evaluating bioinformatics v...

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IEEE visualization 2004 Conference

作者： Saraiya, P North, C Duca, K Virginia Tech Dept Comp Sci Blacksburg VA 24061 USA Virginia Tech Virginia Bioinformat Inst Blacksburg VA 24061 USA

关键词： evaluation/methodology graphical user interfaces (GUI) information visualization visualization systems and software visualization techniques and methodologies

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Output-sensitive 3D line integral convolution

Output-sensitive 3D line integral convolution

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9th Eurographics/IEEE VGTC Symposium on visualization (EuroVis '07)

作者： Falk, Martin Weiskopf, Daniel Univ Stuttgart Visualizat Res Ctr VISUS D-70569 Stuttgart Germany

We propose a largely output- sensitive visualization method for 3D line integral convolution ( LIC) whose rendering speed is mainly independent of the data set size and mostly governed by the complexity of the output on the image plane. Our approach of view- dependent visualization tightly links the LIC generation with the volume rendering of the LIC result in order to avoid the computation of unnecessary LIC points: early- ray termination and empty- space leaping techniques are used to skip the computation of the LIC integral in a lazy- evaluation approach;both ray casting and texture slicing can be used as volume- rendering techniques. The input noise is modeled in object space to allow for temporal coherence under object and camera motion. Different noise models are discussed, covering dense representations based on filtered white noise all the way to sparse representations similar to oriented LIC. Aliasing artifacts are avoided by frequency control over the 3D noise and by employing a 3D variant of MIP mapping. A range of illumination models is applied to the LIC streamlines: different codimension- 2 lighting models and a novel gradient- based illumination model that relies on precomputed gradients and does not require any direct calculation of gradients after the LIC integral is evaluated. We discuss the issue of proper sampling of the LIC and volume- rendering integrals by employing a frequency- space analysis of the noise model and the precomputed gradients. Finally, we demonstrate that our visualization approach lends itself to a fast graphics processing unit ( GPU) implementation that supports both steady and unsteady flow. Therefore, this 3D LIC method allows users to interactively explore 3D flow by means of high- quality, view- dependent, and adaptive LIC volume visualization. Applications to flow visualization in combination with feature extraction and focus- and- context visualization are described, a comparison to previous methods is provided, and a d

关键词： flow visualization visualization techniques and methodologies three-dimensional graphics and realism line integral convolution texture-based vector field visualization 3D flow streamline illumination noise models GPU programming

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SQLVis: Visual Query Representations for Supporting SQL Learners

SQLVis: Visual Query Representations for Supporting SQL Lear...

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IEEE Symposium on Visual Languages and Human-Centric Computing (VL/HCC)

作者： Miedema, Daphne Fletcher, George Eindhoven Univ Technol Eindhoven Netherlands

ISBN: (纸本)9781665445924

SQL is a typical query language for performing data analytics. Although its usage is ubiquitous, learners experience that query formulation in SQL is error-prone and time-consuming. Prior research has shown that this is due to low expressive ease, extensive training requirements and high cognitive load, all of which present a significant burden for SQL learners. Visual representations can assist learners to significantly lower this burden. The current dominant paradigm aims to facilitate SQL querying by helping users to avoid the syntax of SQL. Such Visual Querying Systems (VQS), however, are not effective for SQL learners as they hide the syntax of the language during query formulation, rather than assisting learners to write correct queries in SQL. Furthermore, training with VQSs is system specific, which leads to system dependency for learners. We argue that novices need support from Visual Query Representation (VQR) solutions which, instead, help them in learning how to write correct and portable SQL queries. In this paper we present SQLVis, a VQR to support novice SQL users in query writing. Our system represents the query as written in SQL by the user, which can improve the SQL writing proficiency of its users. Results of an in depth empirical study demonstrate the significant value of SQLVis for learners.

关键词： Query languages visualization techniques and methodologies Computer Science education

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