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 | 2,011 | An Efficient Direct Volume Rendering Approach for Dichromats | 10.1109/TVCG.2011.164 | Color vision deficiency (CVD) affects a high percentage of the population worldwide. When seeing a volume visualization result, persons with CVD may be incapable of discriminating the classification information expressed in the image if the color transfer function or the color blending used in the direct volume rendering is not appropriate. Conventional methods used to address this problem adopt advanced image recoloring techniques to enhance the rendering results frame-by-frame; unfortunately, problematic perceptual results may still be generated. This paper proposes an alternative solution that complements the image recoloring scheme by reconfiguring the components of the direct volume rendering (DVR) pipeline. Our approach optimizes the mapped colors of a transfer function to simulate CVD-friendly effect that is generated by applying the image recoloring to the results with the initial transfer function. The optimization process has a low computational complexity, and only needs to be performed once for a given transfer function. To achieve detail-preserving and perceptually natural semi-transparent effects, we introduce a new color composition mode that works in the color space of dichromats. Experimental results and a pilot study demonstrates that our approach can yield dichromats-friendly and consistent volume visualization in real-time. | false | false | [
"Weifeng Chen 0002",
"Wei Chen 0001",
"Hujun Bao"
] | [] | [] | [] |
Vis | 2,011 | An Interactive Local Flattening Operator to Support Digital Investigations on Artwork Surfaces | 10.1109/TVCG.2011.165 | Analyzing either high-frequency shape detail or any other 2D fields (scalar or vector) embedded over a 3D geometry is a complex task, since detaching the detail from the overall shape can be tricky. An alternative approach is to move to the 2D space, resolving shape reasoning to easier image processing techniques. In this paper we propose a novel framework for the analysis of 2D information distributed over 3D geometry, based on a locally smooth parametrization technique that allows us to treat local 3D data in terms of image content. The proposed approach has been implemented as a sketch-based system that allows to design with a few gestures a set of (possibly overlapping) parameterizations of rectangular portions of the surface. We demonstrate that, due to the locality of the parametrization, the distortion is under an acceptable threshold, while discontinuities can be avoided since the parametrized geometry is always homeomorphic to a disk. We show the effectiveness of the proposed technique to solve specific Cultural Heritage (CH) tasks: the analysis of chisel marks over the surface of a unfinished sculpture and the local comparison of multiple photographs mapped over the surface of an artwork. For this very difficult task, we believe that our framework and the corresponding tool are the first steps toward a computer-based shape reasoning system, able to support CH scholars with a medium they are more used to. | false | false | [
"Nico Pietroni",
"Massimiliano Corsini",
"Paolo Cignoni",
"Roberto Scopigno"
] | [] | [] | [] |
Vis | 2,011 | Artificial Defocus for Displaying Markers in Microscopy Z-Stacks | 10.1109/TVCG.2011.168 | As microscopes have a very shallow depth of field, Z-stacks (i.e. sets of images shot at different focal planes) are often acquired to fully capture a thick sample. Such stacks are viewed by users by navigating them through the mouse wheel. We propose a new technique of visualizing 3D point, line or area markers in such focus stacks, by displaying them with a depth-dependent defocus, simulating the microscope's optics; this leverages on the microscopists' ability to continuously twiddle focus, while implicitly performing a shape-from-focus reconstruction of the 3D structure of the sample. User studies confirm that the approach is effective, and can complement more traditional techniques such as color-based cues. We provide two implementations, one of which computes defocus in real time on the GPU, and examples of their application. | false | false | [
"Alessandro Giusti",
"Pierluigi Taddei",
"Giorgio Corani",
"Luca Maria Gambardella",
"Cristina Magli",
"Luca Gianaroli"
] | [
"HM"
] | [] | [] |
Vis | 2,011 | Asymmetric Tensor field Visualization for Surfaces | 10.1109/TVCG.2011.170 | Asymmetric tensor field visualization can provide important insight into fluid flows and solid deformations. Existing techniques for asymmetric tensor fields focus on the analysis, and simply use evenly-spaced hyperstreamlines on surfaces following eigenvectors and dual-eigenvectors in the tensor field. In this paper, we describe a hybrid visualization technique in which hyperstreamlines and elliptical glyphs are used in real and complex domains, respectively. This enables a more faithful representation of flow behaviors inside complex domains. In addition, we encode tensor magnitude, an important quantity in tensor field analysis, using the density of hyperstreamlines and sizes of glyphs. This allows colors to be used to encode other important tensor quantities. To facilitate quick visual exploration of the data from different viewpoints and at different resolutions, we employ an efficient image-space approach in which hyperstreamlines and glyphs are generated quickly in the image plane. The combination of these techniques leads to an efficient tensor field visualization system for domain scientists. We demonstrate the effectiveness of our visualization technique through applications to complex simulated engine fluid flow and earthquake deformation data. Feedback from domain expert scientists, who are also co-authors, is provided. | false | false | [
"Darrel Palke",
"Zhongzang Lin",
"Guoning Chen",
"Harry Yeh",
"Paul Vincent",
"Robert S. Laramee",
"Eugene Zhang"
] | [] | [] | [] |
Vis | 2,011 | Authalic Parameterization of General Surfaces Using Lie Advection | 10.1109/TVCG.2011.171 | Parameterization of complex surfaces constitutes a major means of visualizing highly convoluted geometric structures as well as other properties associated with the surface. It also enables users with the ability to navigate, orient, and focus on regions of interest within a global view and overcome the occlusions to inner concavities. In this paper, we propose a novel area-preserving surface parameterization method which is rigorous in theory, moderate in computation, yet easily extendable to surfaces of non-disc and closed-boundary topologies. Starting from the distortion induced by an initial parameterization, an area restoring diffeomorphic flow is constructed as a Lie advection of differential 2-forms along the manifold, which yields equality of the area elements between the domain and the original surface at its final state. Existence and uniqueness of result are assured through an analytical derivation. Based upon a triangulated surface representation, we also present an efficient algorithm in line with discrete differential modeling. As an exemplar application, the utilization of this method for the effective visualization of brain cortical imaging modalities is presented. Compared with conformal methods, our method can reveal more subtle surface patterns in a quantitative manner. It, therefore, provides a competitive alternative to the existing parameterization techniques for better surface-based analysis in various scenarios. | false | false | [
"Guangyu Zou",
"Jiaxi Hu",
"Xianfeng Gu",
"Jing Hua 0001"
] | [] | [] | [] |
Vis | 2,011 | Automatic Transfer Functions Based on Informational Divergence | 10.1109/TVCG.2011.173 | In this paper we present a framework to define transfer functions from a target distribution provided by the user. A target distribution can reflect the data importance, or highly relevant data value interval, or spatial segmentation. Our approach is based on a communication channel between a set of viewpoints and a set of bins of a volume data set, and it supports 1D as well as 2D transfer functions including the gradient information. The transfer functions are obtained by minimizing the informational divergence or Kullback-Leibler distance between the visibility distribution captured by the viewpoints and a target distribution selected by the user. The use of the derivative of the informational divergence allows for a fast optimization process. Different target distributions for 1D and 2D transfer functions are analyzed together with importance-driven and view-based techniques. | false | false | [
"Marc Ruiz",
"Anton Bardera",
"Imma Boada",
"Ivan Viola",
"Miquel Feixas",
"Mateu Sbert"
] | [] | [] | [] |
Vis | 2,011 | Branching and Circular Features in High Dimensional Data | 10.1109/TVCG.2011.177 | Large observations and simulations in scientific research give rise to high-dimensional data sets that present many challenges and opportunities in data analysis and visualization. Researchers in application domains such as engineering, computational biology, climate study, imaging and motion capture are faced with the problem of how to discover compact representations of highdimensional data while preserving their intrinsic structure. In many applications, the original data is projected onto low-dimensional space via dimensionality reduction techniques prior to modeling. One problem with this approach is that the projection step in the process can fail to preserve structure in the data that is only apparent in high dimensions. Conversely, such techniques may create structural illusions in the projection, implying structure not present in the original high-dimensional data. Our solution is to utilize topological techniques to recover important structures in high-dimensional data that contains non-trivial topology. Specifically, we are interested in high-dimensional branching structures. We construct local circle-valued coordinate functions to represent such features. Subsequently, we perform dimensionality reduction on the data while ensuring such structures are visually preserved. Additionally, we study the effects of global circular structures on visualizations. Our results reveal never-before-seen structures on real-world data sets from a variety of applications. | false | false | [
"Bei Wang 0001",
"Brian Summa",
"Valerio Pascucci",
"Mikael Vejdemo-Johansson"
] | [] | [] | [] |
Vis | 2,011 | Context Preserving Maps of Tubular Structures | 10.1109/TVCG.2011.182 | When visualizing tubular 3D structures, external representations are often used for guidance and display, and such views in 2D can often contain occlusions. Virtual dissection methods have been proposed where the entire 3D structure can be mapped to the 2D plane, though these will lose context by straightening curved sections. We present a new method of creating maps of 3D tubular structures that yield a succinct view while preserving the overall geometric structure. Given a dominant view plane for the structure, its curve skeleton is first projected to a 2D skeleton. This 2D skeleton is adjusted to account for distortions in length, modified to remove intersections, and optimized to preserve the shape of the original 3D skeleton. Based on this shaped 2D skeleton, a boundary for the map of the object is obtained based on a slicing path through the structure and the radius around the skeleton. The sliced structure is conformally mapped to a rectangle and then deformed via harmonic mapping to match the boundary placement. This flattened map preserves the general geometric context of a 3D object in a 2D display, and rendering of this flattened map can be accomplished using volumetric ray casting. We have evaluated our method on real datasets of human colon models. | false | false | [
"Joseph Marino",
"Wei Zeng 0002",
"Xianfeng Gu",
"Arie E. Kaufman"
] | [] | [] | [] |
Vis | 2,011 | Crepuscular Rays for Tumor Accessibility Planning | 10.1109/TVCG.2011.184 | In modern clinical practice, planning access paths to volumetric target structures remains one of the most important and most complex tasks, and a physician's insufficient experience in this can lead to severe complications or even the death of the patient. In this paper, we present a method for safety evaluation and the visualization of access paths to assist physicians during preoperative planning. As a metaphor for our method, we employ a well-known, and thus intuitively perceivable, natural phenomenon that is usually called crepuscular rays. Using this metaphor, we propose several ways to compute the safety of paths from the region of interest to all tumor voxels and show how this information can be visualized in real-time using a multi-volume rendering system. Furthermore, we show how to estimate the extent of connected safe areas to improve common medical 2D multi-planar reconstruction (MPR) views. We evaluate our method by means of expert interviews, an online survey, and a retrospective evaluation of 19 real abdominal radio-frequency ablation (RFA) interventions, with expert decisions serving as a gold standard. The evaluation results show clear evidence that our method can be successfully applied in clinical practice without introducing substantial overhead work for the acting personnel. Finally, we show that our method is not limited to medical applications and that it can also be useful in other fields. | false | false | [
"Rostislav Khlebnikov",
"Bernhard Kainz",
"Judith Muehl",
"Dieter Schmalstieg"
] | [] | [] | [] |
Vis | 2,011 | Distance Visualization for Interactive 3D Implant Planning | 10.1109/TVCG.2011.189 | An instant and quantitative assessment of spatial distances between two objects plays an important role in interactive applications such as virtual model assembly, medical operation planning, or computational steering. While some research has been done on the development of distance-based measures between two objects, only very few attempts have been reported to visualize such measures in interactive scenarios. In this paper we present two different approaches for this purpose, and we investigate the effectiveness of these approaches for intuitive 3D implant positioning in a medical operation planning system. The first approach uses cylindrical glyphs to depict distances, which smoothly adapt their shape and color to changing distances when the objects are moved. This approach computes distances directly on the polygonal object representations by means of ray/triangle mesh intersection. The second approach introduces a set of slices as additional geometric structures, and uses color coding on surfaces to indicate distances. This approach obtains distances from a precomputed distance field of each object. The major findings of the performed user study indicate that a visualization that can facilitate an instant and quantitative analysis of distances between two objects in interactive 3D scenarios is demanding, yet can be achieved by including additional monocular cues into the visualization. | false | false | [
"Christian Dick",
"Rainer Burgkart",
"Rüdiger Westermann"
] | [] | [] | [] |
Vis | 2,011 | Evaluation of Trend Localization with Multi-Variate Visualizations | 10.1109/TVCG.2011.194 | Multi-valued data sets are increasingly common, with the number of dimensions growing. A number of multi-variate visualization techniques have been presented to display such data. However, evaluating the utility of such techniques for general data sets remains difficult. Thus most techniques are studied on only one data set. Another criticism that could be levied against previous evaluations of multi-variate visualizations is that the task doesn't require the presence of multiple variables. At the same time, the taxonomy of tasks that users may perform visually is extensive. We designed a task, trend localization, that required comparison of multiple data values in a multi-variate visualization. We then conducted a user study with this task, evaluating five multivariate visualization techniques from the literature (Brush Strokes, Data-Driven Spots, Oriented Slivers, Color Blending, Dimensional Stacking) and juxtaposed grayscale maps. We report the results and discuss the implications for both the techniques and the task. | false | false | [
"Mark A. Livingston",
"Jonathan W. Decker"
] | [] | [] | [] |
Vis | 2,011 | Extinction-Based Shading and Illumination in GPU Volume Ray-Casting | 10.1109/TVCG.2011.198 | Direct volume rendering has become a popular method for visualizing volumetric datasets. Even though computers are continually getting faster, it remains a challenge to incorporate sophisticated illumination models into direct volume rendering while maintaining interactive frame rates. In this paper, we present a novel approach for advanced illumination in direct volume rendering based on GPU ray-casting. Our approach features directional soft shadows taking scattering into account, ambient occlusion and color bleeding effects while achieving very competitive frame rates. In particular, multiple dynamic lights and interactive transfer function changes are fully supported. Commonly, direct volume rendering is based on a very simplified discrete version of the original volume rendering integral, including the development of the original exponential extinction into a-blending. In contrast to a-blending forming a product when sampling along a ray, the original exponential extinction coefficient is an integral and its discretization a Riemann sum. The fact that it is a sum can cleverly be exploited to implement volume lighting effects, i.e. soft directional shadows, ambient occlusion and color bleeding. We will show how this can be achieved and how it can be implemented on the GPU. | false | false | [
"Philipp Schlegel",
"Maxim Makhinya",
"Renato Pajarola"
] | [] | [] | [] |
Vis | 2,011 | Feature-Based Statistical Analysis of Combustion Simulation Data | 10.1109/TVCG.2011.199 | We present a new framework for feature-based statistical analysis of large-scale scientific data and demonstrate its effectiveness by analyzing features from Direct Numerical Simulations (DNS) of turbulent combustion. Turbulent flows are ubiquitous and account for transport and mixing processes in combustion, astrophysics, fusion, and climate modeling among other disciplines. They are also characterized by coherent structure or organized motion, i.e. nonlocal entities whose geometrical features can directly impact molecular mixing and reactive processes. While traditional multi-point statistics provide correlative information, they lack nonlocal structural information, and hence, fail to provide mechanistic causality information between organized fluid motion and mixing and reactive processes. Hence, it is of great interest to capture and track flow features and their statistics together with their correlation with relevant scalar quantities, e.g. temperature or species concentrations. In our approach we encode the set of all possible flow features by pre-computing merge trees augmented with attributes, such as statistical moments of various scalar fields, e.g. temperature, as well as length-scales computed via spectral analysis. The computation is performed in an efficient streaming manner in a pre-processing step and results in a collection of meta-data that is orders of magnitude smaller than the original simulation data. This meta-data is sufficient to support a fully flexible and interactive analysis of the features, allowing for arbitrary thresholds, providing per-feature statistics, and creating various global diagnostics such as Cumulative Density Functions (CDFs), histograms, or time-series. We combine the analysis with a rendering of the features in a linked-view browser that enables scientists to interactively explore, visualize, and analyze the equivalent of one terabyte of simulation data. We highlight the utility of this new framework for combustion science; however, it is applicable to many other science domains. | false | false | [
"Janine Bennett",
"Vaidyanathan Krishnamoorthy",
"Shusen Liu",
"Ray W. Grout",
"Evatt R. Hawkes",
"Jacqueline Chen",
"Jason F. Shepherd",
"Valerio Pascucci",
"Peer-Timo Bremer"
] | [] | [] | [] |
Vis | 2,011 | Features in Continuous Parallel Coordinates | 10.1109/TVCG.2011.200 | Continuous Parallel Coordinates (CPC) are a contemporary visualization technique in order to combine several scalar fields, given over a common domain. They facilitate a continuous view for parallel coordinates by considering a smooth scalar field instead of a finite number of straight lines. We show that there are feature curves in CPC which appear to be the dominant structures of a CPC. We present methods to extract and classify them and demonstrate their usefulness to enhance the visualization of CPCs. In particular, we show that these feature curves are related to discontinuities in Continuous Scatterplots (CSP). We show this by exploiting a curve-curve duality between parallel and Cartesian coordinates, which is a generalization of the well-known point-line duality. Furthermore, we illustrate the theoretical considerations. Concluding, we discuss relations and aspects of the CPC's/CSP's features concerning the data analysis. | false | false | [
"Dirk J. Lehmann",
"Holger Theisel"
] | [] | [] | [] |
Vis | 2,011 | Flow Radar Glyphs—Static Visualization of Unsteady Flow with Uncertainty | 10.1109/TVCG.2011.203 | A new type of glyph is introduced to visualize unsteady flow with static images, allowing easier analysis of time-dependent phenomena compared to animated visualization. Adopting the visual metaphor of radar displays, this glyph represents flow directions by angles and time by radius in spherical coordinates. Dense seeding of flow radar glyphs on the flow domain naturally lends itself to multi-scale visualization: zoomed-out views show aggregated overviews, zooming-in enables detailed analysis of spatial and temporal characteristics. Uncertainty visualization is supported by extending the glyph to display possible ranges of flow directions. The paper focuses on 2D flow, but includes a discussion of 3D flow as well. Examples from CFD and the field of stochastic hydrogeology show that it is easy to discriminate regions of different spatiotemporal flow behavior and regions of different uncertainty variations in space and time. The examples also demonstrate that parameter studies can be analyzed because the glyph design facilitates comparative visualization. Finally, different variants of interactive GPU-accelerated implementations are discussed. | false | false | [
"Marcel Hlawatsch",
"Philipp C. Leube",
"Wolfgang Nowak",
"Daniel Weiskopf"
] | [] | [] | [] |
Vis | 2,011 | FoamVis: Visualization of 2D Foam Simulation Data | 10.1109/TVCG.2011.204 | Research in the field of complex fluids such as polymer solutions, particulate suspensions and foams studies how the flow of fluids with different material parameters changes as a result of various constraints. Surface Evolver, the standard solver software used to generate foam simulations, provides large, complex, time-dependent data sets with hundreds or thousands of individual bubbles and thousands of time steps. However this software has limited visualization capabilities, and no foam specific visualization software exists. We describe the foam research application area where, we believe, visualization has an important role to play. We present a novel application that provides various techniques for visualization, exploration and analysis of time-dependent 2D foam simulation data. We show new features in foam simulation data and new insights into foam behavior discovered using our application. | false | false | [
"Dan R. Lipsa",
"Robert S. Laramee",
"Simon J. Cox",
"Tudur Davies"
] | [] | [] | [] |
Vis | 2,011 | GPU-Based Interactive Cut-Surface Extraction From High-Order finite Element fields | 10.1109/TVCG.2011.206 | We present a GPU-based ray-tracing system for the accurate and interactive visualization of cut-surfaces through 3D simulations of physical processes created from spectral/hp high-order finite element methods. When used by the numerical analyst to debug the solver, the ability for the imagery to precisely reflect the data is critical. In practice, the investigator interactively selects from a palette of visualization tools to construct a scene that can answer a query of the data. This is effective as long as the implicit contract of image quality between the individual and the visualization system is upheld. OpenGL rendering of scientific visualizations has worked remarkably well for exploratory visualization for most solver results. This is due to the consistency between the use of first-order representations in the simulation and the linear assumptions inherent in OpenGL (planar fragments and color-space interpolation). Unfortunately, the contract is broken when the solver discretization is of higher-order. There have been attempts to mitigate this through the use of spatial adaptation and/or texture mapping. These methods do a better job of approximating what the imagery should be but are not exact and tend to be view-dependent. This paper introduces new rendering mechanisms that specifically deal with the kinds of native data generated by high-order finite element solvers. The exploratory visualization tools are reassessed and cast in this system with the focus on image accuracy. This is accomplished in a GPU setting to ensure interactivity. | false | false | [
"Blake Nelson",
"Robert M. Kirby",
"Robert Haimes"
] | [] | [] | [] |
Vis | 2,011 | GPU-based Real-Time Approximation of the Ablation Zone for Radiofrequency Ablation | 10.1109/TVCG.2011.207 | Percutaneous radiofrequency ablation (RFA) is becoming a standard minimally invasive clinical procedure for the treatment of liver tumors. However, planning the applicator placement such that the malignant tissue is completely destroyed, is a demanding task that requires considerable experience. In this work, we present a fast GPU-based real-time approximation of the ablation zone incorporating the cooling effect of liver vessels. Weighted distance fields of varying RF applicator types are derived from complex numerical simulations to allow a fast estimation of the ablation zone. Furthermore, the heat-sink effect of the cooling blood flow close to the applicator's electrode is estimated by means of a preprocessed thermal equilibrium representation of the liver parenchyma and blood vessels. Utilizing the graphics card, the weighted distance field incorporating the cooling blood flow is calculated using a modular shader framework, which facilitates the real-time visualization of the ablation zone in projected slice views and in volume rendering. The proposed methods are integrated in our software assistant prototype for planning RFA therapy. The software allows the physician to interactively place virtual RF applicator models. The real-time visualization of the corresponding approximated ablation zone facilitates interactive evaluation of the tumor coverage in order to optimize the applicator's placement such that all cancer cells are destroyed by the ablation. | false | false | [
"Christian Rieder",
"Tim Kröger",
"Christian Schumann",
"Horst K. Hahn"
] | [] | [] | [] |
Vis | 2,011 | Hierarchical Event Selection for Video Storyboards with a Case Study on Snooker Video Visualization | 10.1109/TVCG.2011.208 | Video storyboard, which is a form of video visualization, summarizes the major events in a video using illustrative visualization. There are three main technical challenges in creating a video storyboard, (a) event classification, (b) event selection and (c) event illustration. Among these challenges, (a) is highly application-dependent and requires a significant amount of application specific semantics to be encoded in a system or manually specified by users. This paper focuses on challenges (b) and (c). In particular, we present a framework for hierarchical event representation, and an importance-based selection algorithm for supporting the creation of a video storyboard from a video. We consider the storyboard to be an event summarization for the whole video, whilst each individual illustration on the board is also an event summarization but for a smaller time window. We utilized a 3D visualization template for depicting and annotating events in illustrations. To demonstrate the concepts and algorithms developed, we use Snooker video visualization as a case study, because it has a concrete and agreeable set of semantic definitions for events and can make use of existing techniques of event detection and 3D reconstruction in a reliable manner. Nevertheless, most of our concepts and algorithms developed for challenges (b) and (c) can be applied to other application areas. | false | false | [
"Matthew L. Parry",
"Philip A. Legg",
"David H. S. Chung",
"Iwan W. Griffiths",
"Min Chen 0001"
] | [] | [] | [] |
Vis | 2,011 | Image Plane Sweep Volume Illumination | 10.1109/TVCG.2011.211 | In recent years, many volumetric illumination models have been proposed, which have the potential to simulate advanced lighting effects and thus support improved image comprehension. Although volume ray-casting is widely accepted as the volume rendering technique which achieves the highest image quality, so far no volumetric illumination algorithm has been designed to be directly incorporated into the ray-casting process. In this paper we propose image plane sweep volume illumination (IPSVI), which allows the integration of advanced illumination effects into a GPU-based volume ray-caster by exploiting the plane sweep paradigm. Thus, we are able to reduce the problem complexity and achieve interactive frame rates, while supporting scattering as well as shadowing. Since all illumination computations are performed directly within a single rendering pass, IPSVI does not require any preprocessing nor does it need to store intermediate results within an illumination volume. It therefore has a significantly lower memory footprint than other techniques. This makes IPSVI directly applicable to large data sets. Furthermore, the integration into a GPU-based ray-caster allows for high image quality as well as improved rendering performance by exploiting early ray termination. This paper discusses the theory behind IPSVI, describes its implementation, demonstrates its visual results and provides performance measurements. | false | false | [
"Erik Sundén",
"Anders Ynnerman",
"Timo Ropinski"
] | [] | [] | [] |
Vis | 2,011 | Interactive Multiscale Tensor Reconstruction for Multiresolution Volume Visualization | 10.1109/TVCG.2011.214 | Large scale and structurally complex volume datasets from high-resolution 3D imaging devices or computational simulations pose a number of technical challenges for interactive visual analysis. In this paper, we present the first integration of a multiscale volume representation based on tensor approximation within a GPU-accelerated out-of-core multiresolution rendering framework. Specific contributions include (a) a hierarchical brick-tensor decomposition approach for pre-processing large volume data, (b) a GPU accelerated tensor reconstruction implementation exploiting CUDA capabilities, and (c) an effective tensor-specific quantization strategy for reducing data transfer bandwidth and out-of-core memory footprint. Our multiscale representation allows for the extraction, analysis and display of structural features at variable spatial scales, while adaptive level-of-detail rendering methods make it possible to interactively explore large datasets within a constrained memory footprint. The quality and performance of our prototype system is evaluated on large structurally complex datasets, including gigabyte-sized micro-tomographic volumes. | false | false | [
"Susanne K. Suter",
"José Antonio Iglesias Guitián",
"Fabio Marton",
"Marco Agus",
"Andreas Elsener",
"Christoph P. E. Zollikofer",
"Meenakshisundaram Gopi",
"Enrico Gobbetti",
"Renato Pajarola"
] | [] | [] | [] |
Vis | 2,011 | Interactive Virtual Probing of 4D MRI Blood-Flow | 10.1109/TVCG.2011.215 | Better understanding of hemodynamics conceivably leads to improved diagnosis and prognosis of cardiovascular diseases. Therefore, an elaborate analysis of the blood-flow in heart and thoracic arteries is essential. Contemporary MRI techniques enable acquisition of quantitative time-resolved flow information, resulting in 4D velocity fields that capture the blood-flow behavior. Visual exploration of these fields provides comprehensive insight into the unsteady blood-flow behavior, and precedes a quantitative analysis of additional blood-flow parameters. The complete inspection requires accurate segmentation of anatomical structures, encompassing a time-consuming and hard-to-automate process, especially for malformed morphologies. We present a way to avoid the laborious segmentation process in case of qualitative inspection, by introducing an interactive virtual probe. This probe is positioned semi-automatically within the blood-flow field, and serves as a navigational object for visual exploration. The difficult task of determining position and orientation along the view-direction is automated by a fitting approach, aligning the probe with the orientations of the velocity field. The aligned probe provides an interactive seeding basis for various flow visualization approaches. We demonstrate illustration-inspired particles, integral lines and integral surfaces, conveying distinct characteristics of the unsteady blood-flow. Lastly, we present the results of an evaluation with domain experts, valuing the practical use of our probe and flow visualization techniques. | false | false | [
"Roy van Pelt",
"Javier Oliván Bescós",
"Marcel Breeuwer",
"Rachel E. Clough",
"M. Eduard Gröller",
"Bart M. ter Haar Romeny",
"Anna Vilanova"
] | [] | [] | [] |
Vis | 2,011 | Interactive Volume Visualization of General Polyhedral Grids | 10.1109/TVCG.2011.216 | This paper presents a novel framework for visualizing volumetric data specified on complex polyhedral grids, without the need to perform any kind of a priori tetrahedralization. These grids are composed of polyhedra that often are non-convex and have an arbitrary number of faces, where the faces can be non-planar with an arbitrary number of vertices. The importance of such grids in state-of-the-art simulation packages is increasing rapidly. We propose a very compact, face-based data structure for representing such meshes for visualization, called two-sided face sequence lists (TSFSL), as well as an algorithm for direct GPU-based ray-casting using this representation. The TSFSL data structure is able to represent the entire mesh topology in a 1D TSFSL data array of face records, which facilitates the use of efficient 1D texture accesses for visualization. In order to scale to large data sizes, we employ a mesh decomposition into bricks that can be handled independently, where each brick is then composed of its own TSFSL array. This bricking enables memory savings and performance improvements for large meshes. We illustrate the feasibility of our approach with real-world application results, by visualizing highly complex polyhedral data from commercial state-of-the-art simulation packages. | false | false | [
"Philipp Muigg",
"Markus Hadwiger",
"Helmut Doleisch",
"M. Eduard Gröller"
] | [] | [] | [] |
Vis | 2,011 | Interactive, Graph-based Visual Analysis of High-dimensional, Multi-parameter Fluorescence Microscopy Data in Toponomics | 10.1109/TVCG.2011.217 | In Toponomics, the function protein pattern in cells or tissue (the toponome) is imaged and analyzed for applications in toxicology, new drug development and patient-drug-interaction. The most advanced imaging technique is robot-driven multi-parameter fluorescence microscopy. This technique is capable of co-mapping hundreds of proteins and their distribution and assembly in protein clusters across a cell or tissue sample by running cycles of fluorescence tagging with monoclonal antibodies or other affinity reagents, imaging, and bleaching in situ. The imaging results in complex multi-parameter data composed of one slice or a 3D volume per affinity reagent. Biologists are particularly interested in the localization of co-occurring proteins, the frequency of co-occurrence and the distribution of co-occurring proteins across the cell. We present an interactive visual analysis approach for the evaluation of multi-parameter fluorescence microscopy data in toponomics. Multiple, linked views facilitate the definition of features by brushing multiple dimensions. The feature specification result is linked to all views establishing a focus+context visualization in 3D. In a new attribute view, we integrate techniques from graph visualization. Each node in the graph represents an affinity reagent while each edge represents two co-occurring affinity reagent bindings. The graph visualization is enhanced by glyphs which encode specific properties of the binding. The graph view is equipped with brushing facilities. By brushing in the spatial and attribute domain, the biologist achieves a better understanding of the function protein patterns of a cell. Furthermore, an interactive table view is integrated which summarizes unique fluorescence patterns. We discuss our approach with respect to a cell probe containing lymphocytes and a prostate tissue section. | false | false | [
"Steffen Oeltze-Jafra",
"Wolfgang Freiler",
"Reyk Hillert",
"Helmut Doleisch",
"Bernhard Preim",
"Walter Schubert"
] | [] | [] | [] |
Vis | 2,011 | iView: A Feature Clustering Framework for Suggesting Informative Views in Volume Visualization | 10.1109/TVCG.2011.218 | The unguided visual exploration of volumetric data can be both a challenging and a time-consuming undertaking. Identifying a set of favorable vantage points at which to start exploratory expeditions can greatly reduce this effort and can also ensure that no important structures are being missed. Recent research efforts have focused on entropy-based viewpoint selection criteria that depend on scalar values describing the structures of interest. In contrast, we propose a viewpoint suggestion pipeline that is based on feature-clustering in high-dimensional space. We use gradient/normal variation as a metric to identify interesting local events and then cluster these via k-means to detect important salient composite features. Next, we compute the maximum possible exposure of these composite feature for different viewpoints and calculate a 2D entropy map parameterized in longitude and latitude to point out promising view orientations. Superimposed onto an interactive track-ball interface, users can then directly use this entropy map to quickly navigate to potentially interesting viewpoints where visibility-based transfer functions can be employed to generate volume renderings that minimize occlusions. To give full exploration freedom to the user, the entropy map is updated on the fly whenever a view has been selected, pointing to new and promising but so far unseen view directions. Alternatively, our system can also use a set-cover optimization algorithm to provide a minimal set of views needed to observe all features. The views so generated could then be saved into a list for further inspection or into a gallery for a summary presentation. | false | false | [
"Ziyi Zheng",
"Nafees U. Ahmed",
"Klaus Mueller 0001"
] | [] | [] | [] |
Vis | 2,011 | Load-Balanced Parallel Streamline Generation on Large Scale Vector fields | 10.1109/TVCG.2011.219 | Because of the ever increasing size of output data from scientific simulations, supercomputers are increasingly relied upon to generate visualizations. One use of supercomputers is to generate field lines from large scale flow fields. When generating field lines in parallel, the vector field is generally decomposed into blocks, which are then assigned to processors. Since various regions of the vector field can have different flow complexity, processors will require varying amounts of computation time to trace their particles, causing load imbalance, and thus limiting the performance speedup. To achieve load-balanced streamline generation, we propose a workload-aware partitioning algorithm to decompose the vector field into partitions with near equal workloads. Since actual workloads are unknown beforehand, we propose a workload estimation algorithm to predict the workload in the local vector field. A graph-based representation of the vector field is employed to generate these estimates. Once the workloads have been estimated, our partitioning algorithm is hierarchically applied to distribute the workload to all partitions. We examine the performance of our workload estimation and workload-aware partitioning algorithm in several timings studies, which demonstrates that by employing these methods, better scalability can be achieved with little overhead. | false | false | [
"Boonthanome Nouanesengsy",
"Teng-Yok Lee",
"Han-Wei Shen"
] | [] | [] | [] |
Vis | 2,011 | Multi-Touch Table System for Medical Visualization: Application to Orthopedic Surgery Planning | 10.1109/TVCG.2011.224 | Medical imaging plays a central role in a vast range of healthcare practices. The usefulness of 3D visualizations has been demonstrated for many types of treatment planning. Nevertheless, full access to 3D renderings outside of the radiology department is still scarce even for many image-centric specialties. Our work stems from the hypothesis that this under-utilization is partly due to existing visualization systems not taking the prerequisites of this application domain fully into account. We have developed a medical visualization table intended to better fit the clinical reality. The overall design goals were two-fold: similarity to a real physical situation and a very low learning threshold. This paper describes the development of the visualization table with focus on key design decisions. The developed features include two novel interaction components for touch tables. A user study including five orthopedic surgeons demonstrates that the system is appropriate and useful for this application domain. | false | false | [
"Claes Lundström",
"Thomas Rydell",
"Camilla Forsell",
"Anders Persson",
"Anders Ynnerman"
] | [] | [] | [] |
Vis | 2,011 | Nodes on Ropes: A Comprehensive Data and Control Flow for Steering Ensemble Simulations | 10.1109/TVCG.2011.225 | Flood disasters are the most common natural risk and tremendous efforts are spent to improve their simulation and management. However, simulation-based investigation of actions that can be taken in case of flood emergencies is rarely done. This is in part due to the lack of a comprehensive framework which integrates and facilitates these efforts. In this paper, we tackle several problems which are related to steering a flood simulation. One issue is related to uncertainty. We need to account for uncertain knowledge about the environment, such as levee-breach locations. Furthermore, the steering process has to reveal how these uncertainties in the boundary conditions affect the confidence in the simulation outcome. Another important problem is that the simulation setup is often hidden in a black-box. We expose system internals and show that simulation steering can be comprehensible at the same time. This is important because the domain expert needs to be able to modify the simulation setup in order to include local knowledge and experience. In the proposed solution, users steer parameter studies through the World Lines interface to account for input uncertainties. The transport of steering information to the underlying data-flow components is handled by a novel meta-flow. The meta-flow is an extension to a standard data-flow network, comprising additional nodes and ropes to abstract parameter control. The meta-flow has a visual representation to inform the user about which control operations happen. Finally, we present the idea to use the data-flow diagram itself for visualizing steering information and simulation results. We discuss a case-study in collaboration with a domain expert who proposes different actions to protect a virtual city from imminent flooding. The key to choosing the best response strategy is the ability to compare different regions of the parameter space while retaining an understanding of what is happening inside the data-flow system. | false | false | [
"Jürgen Waser",
"Hrvoje Ribicic",
"Raphael Fuchs",
"Christian Hirsch",
"Benjamin Schindler",
"Günter Blöschl",
"M. Eduard Gröller"
] | [] | [] | [] |
Vis | 2,011 | Projection-Based Metal-Artifact Reduction for Industrial 3D X-ray Computed Tomography | 10.1109/TVCG.2011.228 | Multi-material components, which contain metal parts surrounded by plastic materials, are highly interesting for inspection using industrial 3D X-ray computed tomography (3DXCT). Examples of this application scenario are connectors or housings with metal inlays in the electronic or automotive industry. A major problem of this type of components is the presence of metal, which causes streaking artifacts and distorts the surrounding media in the reconstructed volume. Streaking artifacts and dark-band artifacts around metal components significantly influence the material characterization (especially for the plastic components). In specific cases these artifacts even prevent a further analysis. Due to the nature and the different characteristics of artifacts, the development of an efficient artifact-reduction technique in reconstruction-space is rather complicated. In this paper we present a projection-space pipeline for metal-artifacts reduction. The proposed technique first segments the metal in the spatial domain of the reconstructed volume in order to separate it from the other materials. Then metal parts are forward-projected on the set of projections in a way that metal-projection regions are treated as voids. Subsequently the voids, which are left by the removed metal, are interpolated in the 2D projections. Finally, the metal is inserted back into the reconstructed 3D volume during the fusion stage. We present a visual analysis tool, allowing for interactive parameter estimation of the metal segmentation. The results of the proposed artifact-reduction technique are demonstrated on a test part as well as on real world components. For these specimens we achieve a significant reduction of metal artifacts, allowing an enhanced material characterization. | false | false | [
"Artem Amirkhanov",
"Christoph Heinzl",
"Michael Reiter",
"Johann Kastner",
"M. Eduard Gröller"
] | [] | [] | [] |
Vis | 2,011 | Quasi Interpolation With Voronoi Splines | 10.1109/TVCG.2011.230 | We present a quasi interpolation framework that attains the optimal approximation-order of Voronoi splines for reconstruction of volumetric data sampled on general lattices. The quasi interpolation framework of Voronoi splines provides an unbiased reconstruction method across various lattices. Therefore this framework allows us to analyze and contrast the sampling-theoretic performance of general lattices, using signal reconstruction, in an unbiased manner. Our quasi interpolation methodology is implemented as an efficient FIR filter that can be applied online or as a preprocessing step. We present visual and numerical experiments that demonstrate the improved accuracy of reconstruction across lattices, using the quasi interpolation framework. | false | false | [
"Mahsa Mirzargar",
"Alireza Entezari"
] | [] | [] | [] |
Vis | 2,011 | Saliency-Assisted Navigation of Very Large Landscape Images | 10.1109/TVCG.2011.231 | The field of visualization has addressed navigation of very large datasets, usually meshes and volumes. Significantly less attention has been devoted to the issues surrounding navigation of very large images. In the last few years the explosive growth in the resolution of camera sensors and robotic image acquisition techniques has widened the gap between the display and image resolutions to three orders of magnitude or more. This paper presents the first steps towards navigation of very large images, particularly landscape images, from an interactive visualization perspective. The grand challenge in navigation of very large images is identifying regions of potential interest. In this paper we outline a three-step approach. In the first step we use multi-scale saliency to narrow down the potential areas of interest. In the second step we outline a method based on statistical signatures to further cull out regions of high conformity. In the final step we allow a user to interactively identify the exceptional regions of high interest that merit further attention. We show that our approach of progressive elicitation is fast and allows rapid identification of regions of interest. Unlike previous work in this area, our approach is scalable and computationally reasonable on very large images. We validate the results of our approach by comparing them to user-tagged regions of interest on several very large landscape images from the Internet. | false | false | [
"Cheuk Yiu Ip",
"Amitabh Varshney"
] | [
"HM"
] | [] | [] |
Vis | 2,011 | Straightening Tubular Flow for Side-by-Side Visualization | 10.1109/TVCG.2011.235 | Flows through tubular structures are common in many fields, including blood flow in medicine and tubular fluid flows in engineering. The analysis of such flows is often done with a strong reference to the main flow direction along the tubular boundary. In this paper we present an approach for straightening the visualization of tubular flow. By aligning the main reference direction of the flow, i.e., the center line of the bounding tubular structure, with one axis of the screen, we are able to natively juxtapose (1.) different visualizations of the same flow, either utilizing different flow visualization techniques, or by varying parameters of a chosen approach such as the choice of seeding locations for integration-based flow visualization, (2.) the different time steps of a time-dependent flow, (3.) different projections around the center line , and (4.) quantitative flow visualizations in immediate spatial relation to the more qualitative classical flow visualization. We describe how to utilize this approach for an informative interactive visual analysis. We demonstrate the potential of our approach by visualizing two datasets from two different fields: an arterial blood flow measurement and a tubular gas flow simulation from the automotive industry. | false | false | [
"Paolo Angelelli",
"Helwig Hauser"
] | [] | [] | [] |
Vis | 2,011 | Symmetry in Scalar field Topology | 10.1109/TVCG.2011.236 | Study of symmetric or repeating patterns in scalar fields is important in scientific data analysis because it gives deep insights into the properties of the underlying phenomenon. Though geometric symmetry has been well studied within areas like shape processing, identifying symmetry in scalar fields has remained largely unexplored due to the high computational cost of the associated algorithms. We propose a computationally efficient algorithm for detecting symmetric patterns in a scalar field distribution by analysing the topology of level sets of the scalar field. Our algorithm computes the contour tree of a given scalar field and identifies subtrees that are similar. We define a robust similarity measure for comparing subtrees of the contour tree and use it to group similar subtrees together. Regions of the domain corresponding to subtrees that belong to a common group are extracted and reported to be symmetric. Identifying symmetry in scalar fields finds applications in visualization, data exploration, and feature detection. We describe two applications in detail: symmetry-aware transfer function design and symmetry-aware isosurface extraction. | false | false | [
"Dilip Mathew Thomas",
"Vijay Natarajan"
] | [] | [] | [] |
Vis | 2,011 | The Effect of Colour and Transparency on the Perception of Overlaid Grids | 10.1109/TVCG.2011.242 | Overlaid reference elements need to be sufficiently visible to effectively relate to the underlying information, but not so obtrusive that they clutter the presentation. We seek to create guidelines for presenting such structures through experimental studies to define boundary conditions for visual intrusiveness. We base our work on the practice of designers, who use transparency to integrate overlaid grids with their underlying imagery. Previous work discovered a useful range of alpha values for black or white grids overlayed on scatterplot images rendered in shades of gray over gray backgrounds of different lightness values. This work compares black grids to blue and red ones on different image types of scatterplots and maps. We expected that the coloured grids over grayscale images would be more visually salient than black ones, resulting in lower alpha values. Instead, we found that there was no significant difference between the boundaries set for red and black grids, but that the boundaries for blue grids were set consistently higher (more opaque). As in our previous study, alpha values are affected by image density rather than image type, and are consistently lower than many default settings. These results have implications for the design of subtle reference structures. | false | false | [
"Lyn Bartram",
"Billy Cheung",
"Maureen C. Stone"
] | [] | [] | [] |
Vis | 2,011 | The FLOWLENS: A Focus-and-Context Visualization Approach for Exploration of Blood Flow in Cerebral Aneurysms | 10.1109/TVCG.2011.243 | Blood flow and derived data are essential to investigate the initiation and progression of cerebral aneurysms as well as their risk of rupture. An effective visual exploration of several hemodynamic attributes like the wall shear stress (WSS) and the inflow jet is necessary to understand the hemodynamics. Moreover, the correlation between focus-and-context attributes is of particular interest. An expressive visualization of these attributes and anatomic information requires appropriate visualization techniques to minimize visual clutter and occlusions. We present the FLOWLENS as a focus-and-context approach that addresses these requirements. We group relevant hemodynamic attributes to pairs of focus-and-context attributes and assign them to different anatomic scopes. For each scope, we propose several FLOWLENS visualization templates to provide a flexible visual filtering of the involved hemodynamic pairs. A template consists of the visualization of the focus attribute and the additional depiction of the context attribute inside the lens. Furthermore, the FLOWLENS supports local probing and the exploration of attribute changes over time. The FLOWLENS minimizes visual cluttering, occlusions, and provides a flexible exploration of a region of interest. We have applied our approach to seven representative datasets, including steady and unsteady flow data from CFD simulations and 4D PC-MRI measurements. Informal user interviews with three domain experts confirm the usefulness of our approach. | false | false | [
"Rocco Gasteiger",
"Mathias Neugebauer",
"Oliver Beuing",
"Bernhard Preim"
] | [] | [] | [] |
Vis | 2,011 | Topological Spines: A Structure-preserving Visual Representation of Scalar fields | 10.1109/TVCG.2011.244 | We present topological spines-a new visual representation that preserves the topological and geometric structure of a scalar field. This representation encodes the spatial relationships of the extrema of a scalar field together with the local volume and nesting structure of the surrounding contours. Unlike other topological representations, such as contour trees, our approach preserves the local geometric structure of the scalar field, including structural cycles that are useful for exposing symmetries in the data. To obtain this representation, we describe a novel mechanism based on the extraction of extremum graphs-sparse subsets of the Morse-Smale complex that retain the important structural information without the clutter and occlusion problems that arise from visualizing the entire complex directly. Extremum graphs form a natural multiresolution structure that allows the user to suppress noise and enhance topological features via the specification of a persistence range. Applications of our approach include the visualization of 3D scalar fields without occlusion artifacts, and the exploratory analysis of high-dimensional functions. | false | false | [
"Carlos D. Correa",
"Peter Lindstrom 0001",
"Peer-Timo Bremer"
] | [] | [] | [] |
Vis | 2,011 | Towards Robust Topology of Sparsely Sampled Data | 10.1109/TVCG.2011.245 | Sparse, irregular sampling is becoming a necessity for reconstructing large and high-dimensional signals. However, the analysis of this type of data remains a challenge. One issue is the robust selection of neighborhoods - a crucial part of analytic tools such as topological decomposition, clustering and gradient estimation. When extracting the topology of sparsely sampled data, common neighborhood strategies such as k-nearest neighbors may lead to inaccurate results, either due to missing neighborhood connections, which introduce false extrema, or due to spurious connections, which conceal true extrema. Other neighborhoods, such as the Delaunay triangulation, are costly to compute and store even in relatively low dimensions. In this paper, we address these issues. We present two new types of neighborhood graphs: a variation on and a generalization of empty region graphs, which considerably improve the robustness of neighborhood-based analysis tools, such as topological decomposition. Our findings suggest that these neighborhood graphs lead to more accurate topological representations of low- and high- dimensional data sets at relatively low cost, both in terms of storage and computation time. We describe the implications of our work in the analysis and visualization of scalar functions, and provide general strategies for computing and applying our neighborhood graphs towards robust data analysis. | false | false | [
"Carlos D. Correa",
"Peter Lindstrom 0001"
] | [
"BP"
] | [] | [] |
Vis | 2,011 | TransGraph: Hierarchical Exploration of Transition Relationships in Time-Varying Volumetric Data | 10.1109/TVCG.2011.246 | A fundamental challenge for time-varying volume data analysis and visualization is the lack of capability to observe and track data change or evolution in an occlusion-free, controllable, and adaptive fashion. In this paper, we propose to organize a timevarying data set into a hierarchy of states. By deriving transition probabilities among states, we construct a global map that captures the essential transition relationships in the time-varying data. We introduce the TransGraph, a graph-based representation to visualize hierarchical state transition relationships. The TransGraph not only provides a visual mapping that abstracts data evolution over time in different levels of detail, but also serves as a navigation tool that guides data exploration and tracking. The user interacts with the TransGraph and makes connection to the volumetric data through brushing and linking. A set of intuitive queries is provided to enable knowledge extraction from time-varying data. We test our approach with time-varying data sets of different characteristics and the results show that the TransGraph can effectively augment our ability in understanding time-varying data. | false | false | [
"Yi Gu",
"Chaoli Wang 0001"
] | [] | [] | [] |
Vis | 2,011 | Tuner: Principled Parameter finding for Image Segmentation Algorithms Using Visual Response Surface Exploration | 10.1109/TVCG.2011.248 | In this paper we address the difficult problem of parameter-finding in image segmentation. We replace a tedious manual process that is often based on guess-work and luck by a principled approach that systematically explores the parameter space. Our core idea is the following two-stage technique: We start with a sparse sampling of the parameter space and apply a statistical model to estimate the response of the segmentation algorithm. The statistical model incorporates a model of uncertainty of the estimation which we use in conjunction with the actual estimate in (visually) guiding the user towards areas that need refinement by placing additional sample points. In the second stage the user navigates through the parameter space in order to determine areas where the response value (goodness of segmentation) is high. In our exploration we rely on existing ground-truth images in order to evaluate the "goodness" of an image segmentation technique. We evaluate its usefulness by demonstrating this technique on two image segmentation algorithms: a three parameter model to detect microtubules in electron tomograms and an eight parameter model to identify functional regions in dynamic Positron Emission Tomography scans. | false | false | [
"Thomas Torsney-Weir",
"Ahmed Saad",
"Torsten Möller",
"Hans-Christian Hege",
"Britta Weber",
"Jean-Marc Verbavatz",
"Steven Bergner"
] | [
"TT"
] | [] | [] |
Vis | 2,011 | Two-Dimensional Time-Dependent Vortex Regions Based on the Acceleration Magnitude | 10.1109/TVCG.2011.249 | Acceleration is a fundamental quantity of flow fields that captures Galilean invariant properties of particle motion. Considering the magnitude of this field, minima represent characteristic structures of the flow that can be classified as saddle- or vortex-like. We made the interesting observation that vortex-like minima are enclosed by particularly pronounced ridges. This makes it possible to define boundaries of vortex regions in a parameter-free way. Utilizing scalar field topology, a robust algorithm can be designed to extract such boundaries. They can be arbitrarily shaped. An efficient tracking algorithm allows us to display the temporal evolution of vortices. Various vortex models are used to evaluate the method. We apply our method to two-dimensional model systems from computational fluid dynamics and compare the results to those arising from existing definitions. | false | false | [
"Jens Kasten",
"Jan Reininghaus",
"Ingrid Hotz",
"Hans-Christian Hege"
] | [] | [] | [] |
Vis | 2,011 | Visualization of AMR Data With Multi-Level Dual-Mesh Interpolation | 10.1109/TVCG.2011.252 | We present a new technique for providing interpolation within cell-centered Adaptive Mesh Refinement (AMR) data that achieves C<sup>0</sup> continuity throughout the 3D domain. Our technique improves on earlier work in that it does not require that adjacent patches differ by at most one refinement level. Our approach takes the dual of each mesh patch and generates "stitching cells" on the fly to fill the gaps between dual meshes. We demonstrate applications of our technique with data from Enzo, an AMR cosmological structure formation simulation code. We show ray-cast visualizations that include contributions from particle data (dark matter and stars, also output by Enzo) and gridded hydrodynamic data. We also show results from isosurface studies, including surfaces in regions where adjacent patches differ by more than one refinement level. | false | false | [
"Patrick J. Moran",
"David Ellsworth"
] | [] | [] | [] |
Vis | 2,011 | Visualization of Topological Structures in Area-Preserving Maps | 10.1109/TVCG.2011.254 | Area-preserving maps are found across a wide range of scientific and engineering problems. Their study is made challenging by the significant computational effort typically required for their inspection but more fundamentally by the fractal complexity of salient structures. The visual inspection of these maps reveals a remarkable topological picture consisting of fixed (or periodic) points embedded in so-called island chains, invariant manifolds, and regions of ergodic behavior. This paper is concerned with the effective visualization and precise topological analysis of area-preserving maps with two degrees of freedom from numerical or analytical data. Specifically, a method is presented for the automatic extraction and characterization of fixed points and the computation of their invariant manifolds, also known as separatrices, to yield a complete picture of the structures present within the scale and complexity bounds selected by the user. This general approach offers a significant improvement over the visual representations that are so far available for area-preserving maps. The technique is demonstrated on a numerical simulation of magnetic confinement in a fusion reactor. | false | false | [
"Xavier Tricoche",
"Christoph Garth",
"Allen R. Sanderson"
] | [] | [] | [] |
Vis | 2,011 | Volume Analysis Using Multimodal Surface Similarity | 10.1109/TVCG.2011.258 | The combination of volume data acquired by multiple modalities has been recognized as an important but challenging task. Modalities often differ in the structures they can delineate and their joint information can be used to extend the classification space. However, they frequently exhibit differing types of artifacts which makes the process of exploiting the additional information non-trivial. In this paper, we present a framework based on an information-theoretic measure of isosurface similarity between different modalities to overcome these problems. The resulting similarity space provides a concise overview of the differences between the two modalities, and also serves as the basis for an improved selection of features. Multimodal classification is expressed in terms of similarities and dissimilarities between the isosurfaces of individual modalities, instead of data value combinations. We demonstrate that our approach can be used to robustly extract features in applications such as dual energy computed tomography of parts in industrial manufacturing. | false | false | [
"Martin Haidacher",
"Stefan Bruckner",
"M. Eduard Gröller"
] | [] | [] | [] |
Vis | 2,011 | Voronoi-Based Extraction and Visualization of Molecular Paths | 10.1109/TVCG.2011.259 | Visual analysis is widely used to study the behavior of molecules. Of particular interest are the analysis of molecular interactions and the investigation of binding sites. For large molecules, however, it is difficult to detect possible binding sites and paths leading to these sites by pure visual inspection. In this paper, we present new methods for the computation and visualization of potential molecular paths. Using a novel filtering method, we extract the significant paths from the Voronoi diagram of spheres. For the interactive visualization of molecules and their paths, we present several methods using deferred shading and other state-of-theart techniques. To allow for a fast overview of reachable regions of the molecule, we illuminate the molecular surface using a large number of light sources placed on the extracted paths. We also provide a method to compute the extension surface of selected paths and visualize it using the skin surface. Furthermore, we use the extension surface to clip the molecule to allow easy visual tracking of even deeply buried paths. The methods are applied to several proteins to demonstrate their usefulness. | false | false | [
"Norbert Lindow",
"Daniel Baum",
"Hans-Christian Hege"
] | [
"HM"
] | [] | [] |
Vis | 2,011 | Vortex Visualization in Ultra Low Reynolds Number Insect Flight | 10.1109/TVCG.2011.260 | We present the visual analysis of a biologically inspired CFD simulation of the deformable flapping wings of a dragonfly as it takes off and begins to maneuver, using vortex detection and integration-based flow lines. The additional seed placement and perceptual challenges introduced by having multiple dynamically deforming objects in the highly unsteady 3D flow domain are addressed. A brief overview of the high speed photogrammetry setup used to capture the dragonfly takeoff, parametric surfaces used for wing reconstruction, CFD solver and underlying flapping flight theory is presented to clarify the importance of several unsteady flight mechanisms, such as the leading edge vortex, that are captured visually. A novel interactive seed placement method is used to simplify the generation of seed curves that stay in the vicinity of relevant flow phenomena as they move with the flapping wings. This method allows a user to define and evaluate the quality of a seed's trajectory over time while working with a single time step. The seed curves are then used to place particles, streamlines and generalized streak lines. The novel concept of flowing seeds is also introduced in order to add visual context about the instantaneous vector fields surrounding smoothly animate streak lines. Tests show this method to be particularly effective at visually capturing vortices that move quickly or that exist for a very brief period of time. In addition, an automatic camera animation method is used to address occlusion issues caused when animating the immersed wing boundaries alongside many geometric flow lines. Each visualization method is presented at multiple time steps during the up-stroke and down-stroke to highlight the formation, attachment and shedding of the leading edge vortices in pairs of wings. Also, the visualizations show evidence of wake capture at stroke reversal which suggests the existence of previously unknown unsteady lift generation mechanisms that are unique to quad wing insects. | false | false | [
"Christopher Koehler",
"Thomas Wischgoll",
"Haibo Dong",
"Zachary Gaston"
] | [] | [] | [] |
Vis | 2,011 | WYSIWYG (What You See is What You Get) Volume Visualization | 10.1109/TVCG.2011.261 | In this paper, we propose a volume visualization system that accepts direct manipulation through a sketch-based What You See Is What You Get (WYSIWYG) approach. Similar to the operations in painting applications for 2D images, in our system, a full set of tools have been developed to enable direct volume rendering manipulation of color, transparency, contrast, brightness, and other optical properties by brushing a few strokes on top of the rendered volume image. To be able to smartly identify the targeted features of the volume, our system matches the sparse sketching input with the clustered features both in image space and volume space. To achieve interactivity, both special algorithms to accelerate the input identification and feature matching have been developed and implemented in our system. Without resorting to tuning transfer function parameters, our proposed system accepts sparse stroke inputs and provides users with intuitive, flexible and effective interaction during volume data exploration and visualization. | false | false | [
"Hanqi Guo 0001",
"Ningyu Mao",
"Xiaoru Yuan"
] | [] | [] | [] |
VAST | 2,011 | 3D Visualization of temporal changes in bloggers' activities and interests | 10.1109/VAST.2011.6102475 | This paper presents a novel system for analyzing temporal changes in bloggers' activities and interests on a topic through a 3D visualization of dependency structures related to the topic. Having a dependency database built from a blog archive, our 3D visualization framework helps users to interactively exploring temporal changes in bloggers' activities and interests related to the topic. | false | false | [
"Masahiko Itoh",
"Naoki Yoshinaga 0001",
"Masashi Toyoda",
"Masaru Kitsuregawa"
] | [] | [] | [] |
VAST | 2,011 | A state transition approach to understanding users' interactions | 10.1109/VAST.2011.6102476 | Understanding users' interactions is considered as one of the important research topics in visual analytics. Although numerous empirical user studies have been performed to understand a user's interaction, a limited study has been successful in connecting the user's interaction to his/her reasoning. In this paper, we present an approach of understanding experts' interactive analysis by connecting their interactions to conclusions (i.e. findings) through a state transition approach. | false | false | [
"Dong Hyun Jeong",
"Soo-Yeon Ji",
"William Ribarsky",
"Remco Chang"
] | [] | [] | [] |
VAST | 2,011 | A two-stage framework for designing visual analytics system in organizational environments | 10.1109/VAST.2011.6102463 | A perennially interesting research topic in the field of visual analytics is how to effectively develop systems that support organizational users' decision-making and reasoning processes. The problem is, however, most domain analytical practices generally vary from organization to organization. This leads to diverse designs of visual analytics systems in incorporating domain analytical processes, making it difficult to generalize the success from one domain to another. Exacerbating this problem is the dearth of general models of analytical workflows available to enable such timely and effective designs. To alleviate these problems, we present a two-stage framework for informing the design of a visual analytics system. This design framework builds upon and extends current practices pertaining to analytical workflow and focuses, in particular, on incorporating both general domain analysis processes as well as individual's analytical activities. We illustrate both stages and their design components through examples, and hope this framework will be useful for designing future visual analytics systems. We validate the soundness of our framework with two visual analytics systems, namely Entity Workspace [8] and PatViz [37]. | false | false | [
"Derek Xiaoyu Wang",
"Wenwen Dou",
"Thomas Butkiewicz",
"Eric A. Bier",
"William Ribarsky"
] | [] | [] | [] |
VAST | 2,011 | A visual analytics process for maritime resource allocation and risk assessment | 10.1109/VAST.2011.6102460 | In this paper, we present our collaborative work with the U.S. Coast Guard's Ninth District and Atlantic Area Commands where we developed a visual analytics system to analyze historic response operations and assess the potential risks in the maritime environment associated with the hypothetical allocation of Coast Guard resources. The system includes linked views and interactive displays that enable the analysis of trends, patterns and anomalies among the U.S. Coast Guard search and rescue (SAR) operations and their associated sorties. Our system allows users to determine the potential change in risks associated with closing certain stations in terms of response time, potential lives and property lost and provides optimal direction as to the nearest available station. We provide maritime risk assessment tools that allow analysts to explore Coast Guard coverage for SAR operations and identify regions of high risk. The system also enables a thorough assessment of all SAR operations conducted by each Coast Guard station in the Great Lakes region. Our system demonstrates the effectiveness of visual analytics in analyzing risk within the maritime domain and is currently being used by analysts at the Coast Guard Atlantic Area. | false | false | [
"Abish Malik",
"Ross Maciejewski",
"Ben Maule",
"David S. Ebert"
] | [] | [] | [] |
VAST | 2,011 | A visual navigation system for querying neural stem cell imaging data | 10.1109/VAST.2011.6102459 | Cellular biology deals with studying the behavior of cells. Current time-lapse imaging microscopes help us capture the progress of experiments at intervals that allow for understanding of the dynamic and kinematic behavior of the cells. On the other hand, these devices generate such massive amounts of data (250GB of data per experiment) that manual sieving of data to identify interesting patterns becomes virtually impossible. In this paper we propose an end-to-end system to analyze time-lapse images of the cultures of human neural stem cells (hNSC), that includes an image processing system to analyze the images to extract all the relevant geometric and statistical features within and between images, a database management system to manage and handle queries on the data, a visual analytic system to navigate through the data, and a visual query system to explore different relationships and correlations between the parameters. In each stage of the pipeline we make novel algorithmic and conceptual contributions, and the entire system design is motivated by many different yet unanswered exploratory questions pursued by our neurobiologist collaborators. With a few examples we show how such abstract biological queries can be analyzed and answered by our system. | false | false | [
"Ishwar Kulkarni",
"Shanaz Y. Mistry",
"Brian Cummings",
"Meenakshisundaram Gopi"
] | [] | [] | [] |
VAST | 2,011 | An integrated visualization on network events VAST 2011 mini challenge #2 award: "Outstanding integrated overview display" | 10.1109/VAST.2011.6102493 | To visualize security trends for the data set provided by the VAST 2011 Mini Challenge #2 a custom tool has been developed. Open source tools [1,2], web programming languages [4,7] and an open source database [3] has been used to work with the data and create a visualization for security log files containing network security trends. In this paper, the tools and methods used for the analysis are described. The methods include the log synchronization with different timezone and the development of heat maps and parallel coordinates charts. To develop the visualization, Processing and Canvas [4,7] was used. | false | false | [
"Walter Marcelo Lamagna"
] | [] | [] | [] |
VAST | 2,011 | Analysis of large digital collections with interactive visualization | 10.1109/VAST.2011.6102462 | To make decisions about the long-term preservation and access of large digital collections, archivists gather information such as the collections' contents, their organizational structure, and their file format composition. To date, the process of analyzing a collection - from data gathering to exploratory analysis and final conclusions - has largely been conducted using pen and paper methods. To help archivists analyze large-scale digital collections for archival purposes, we developed an interactive visual analytics application. The application narrows down different kinds of information about the collection, and presents them as meaningful data views. Multiple views and analysis features can be linked or unlinked on demand to enable researchers to compare and contrast different analyses, and to identify trends. We describe and present two user scenarios to show how the application allowed archivists to learn about a collection with accuracy, facilitated decision-making, and helped them arrive at conclusions. | false | false | [
"Weijia Xu",
"Maria Esteva",
"Suyog Dott Jain",
"Varun Jain"
] | [] | [] | [] |
VAST | 2,011 | Analyst's workspace: Protecting vastopolis | 10.1109/VAST.2011.6102495 | Analyst's Workspace is a sensemaking environment designed specifically for use of large, high-resolution displays. It employs a spatial workspace to integrate foraging and synthesis activities into a unified process. In this paper we describe how Analyst's Workspace solved the VAST 2011 mini-challenge #3 and discuss some of the unique features of the environment. | false | false | [
"Christopher Andrews",
"Mahmud Shahriar Hossain",
"Samah Gad",
"Naren Ramakrishnan",
"Chris North 0001"
] | [] | [] | [] |
VAST | 2,011 | Analysts aren't machines: Inferring frustration through visualization interaction | 10.1109/VAST.2011.6102473 | Recent work in visual analytics has explored the extent to which information regarding analyst action and reasoning can be inferred from interaction. However, these methods typically rely on humans instead of automatic extraction techniques. Furthermore, there is little discussion regarding the role of user frustration when interacting with a visual interface. We demonstrate that automatic extraction of user frustration is possible given action-level visualization interaction logs. An experiment is described which collects data that accurately reflects user emotion transitions and corresponding interaction sequences. This data is then used in building HiddenMarkov Models (HMMs) which statistically connect interaction events with frustration. The capabilities of HMMs in predicting user frustration are tested using standard machine learning evaluation methods. The resulting classifier serves as a suitable predictor of user frustration that performs similarly across different users and datasets. | false | false | [
"Lane Harrison",
"Wenwen Dou",
"Aidong Lu",
"William Ribarsky",
"Derek Xiaoyu Wang"
] | [] | [] | [] |
VAST | 2,011 | Automated measures for interpretable dimensionality reduction for visual classification: A user study | 10.1109/VAST.2011.6102474 | This paper studies the interpretability of transformations of labeled higher dimensional data into a 2D representation (scatterplots) for visual classification.<sup>1</sup>In this context, the term interpretability has two components: the interpretability of the visualization (the image itself) and the interpretability of the visualization axes (the data transformation functions). We define a data transformation function as any linear or non-linear function of the original variables mapping the data into 1D. Even for a small dataset, the space of possible data transformations is beyond the limit of manual exploration, therefore it is important to develop automated techniques that capture both aspects of interpretability so that they can be used to guide the search process without human intervention. The goal of the search process is to find a smaller number of interpretable data transformations for the users to explore. We briefly discuss how we used such automated measures in an evolutionary computing based data dimensionality reduction application for visual analytics. In this paper, we present a two-part user study in which we separately investigated how humans rated the visualizations of labeled data and comprehensibility of mathematical expressions that could be used as data transformation functions. In the first part, we compared human perception with a number of automated measures from the machine learning and visual analytics literature. In the second part, we studied how various structural properties of an expression related to its interpretability. | false | false | [
"Ilknur Icke",
"Andrew Rosenberg"
] | [] | [] | [] |
VAST | 2,011 | BaobabView: Interactive construction and analysis of decision trees | 10.1109/VAST.2011.6102453 | We present a system for the interactive construction and analysis of decision trees that enables domain experts to bring in domain specific knowledge. We identify different user tasks and corresponding requirements, and develop a system incorporating a tight integration of visualization, interaction and algorithmic support. Domain experts are supported in growing, pruning, optimizing and analysing decision trees. Furthermore, we present a scalable decision tree visualization optimized for exploration. We show the effectiveness of our approach by applying the methods to two use cases. The first case illustrates the advantages of interactive construction, the second case demonstrates the effectiveness of analysis of decision trees and exploration of the structure of the data. | false | false | [
"Stef van den Elzen",
"Jarke J. van Wijk"
] | [] | [] | [] |
VAST | 2,011 | Characterizing the intelligence analysis process: Informing visual analytics design through a longitudinal field study | 10.1109/VAST.2011.6102438 | While intelligence analysis has been a primary target domain for visual analytics system development, relatively little user and task analysis has been conducted within this area. Our research community's understanding of the work processes and practices of intelligence analysts is not deep enough to adequately address their needs. Without a better understanding of the analysts and their problems, we cannot build visual analytics systems that integrate well with their work processes and truly provide benefit to them. In order to close this knowledge gap, we conducted a longitudinal, observational field study of intelligence analysts in training within the intelligence program at Mercyhurst College. We observed three teams of analysts, each working on an intelligence problem for a ten-week period. Based upon study findings, we describe and characterize processes and methods of intelligence analysis that we observed, make clarifications regarding the processes and practices, and suggest design implications for visual analytics systems for intelligence analysis. | false | false | [
"Youn ah Kang",
"John T. Stasko"
] | [] | [] | [] |
VAST | 2,011 | City sentinel - VAST 2011 mini challenge 1 award: "Outstanding integration of computational and visual methods" | 10.1109/VAST.2011.6102485 | We present City Sentinel, an in-house built visual analytic software capable of handling a large collection of textual documents by combining diverse text mining and visualization tools. We applied this tool for the Vast Challenge 2011, Mini Challenge 1 over millions of tweet messages. We demonstrate how City Sentinel aided the analyst in retrieving the hidden information from the tweet messages to analyze and locate a hypothetical epidemic outbreak. | false | false | [
"Norbert Bánfi",
"László Dudás",
"Zsolt Fekete",
"Julianna Göbölös-Szabó",
"András Lukács",
"Ádám Nagy",
"Adrienn Szabó",
"Zoltán Szabó 0002",
"Gábor Szücs"
] | [] | [] | [] |
VAST | 2,011 | epSpread - Storyboarding for visual analytics | 10.1109/VAST.2011.6102489 | We present epSpread, an analysis and storyboarding tool for geolocated microblogging data. Individual time points and ranges are analysed through queries, heatmaps, word clouds and streamgraphs. The underlying narrative is shown on a storyboard-style timeline for discussion, refinement and presentation. The tool was used to analyse data from the VAST Challenge 2011 Mini-Challenge 1, tracking the spread of an epidemic using microblogging data. In this article we describe how the tool was used to identify the origin and track the spread of the epidemic. | false | false | [
"Llyr ap Cenydd",
"Rick Walker",
"Serban R. Pop",
"Helen C. Miles",
"Chris J. Hughes",
"William John Teahan",
"Jonathan Roberts 0002"
] | [] | [] | [] |
VAST | 2,011 | Evaluation of large display interaction using smart phones | 10.1109/VAST.2011.6102466 | Visual analytics, “the science of analytical reasoning facilitated by visual interactive interfaces” [5], puts high demands on the applications visualization as well as interaction capabilities. Due to their size large high-resolution screens have become popular display devices, especially when used in collaborative data analysis scenarios. However, traditional interaction methods based on combinations of computer mice and keyboards often do not scale to the number of users or the size of the display. Modern smart phones featuring multi-modal input/output and considerable memory offer a way to address these issues. In the last couple of years they have become common everyday life gadgets. In this paper we conduct an extensive user study comparing the experience of test candidates when using traditional input devices and metaphors with the one when using new smart phone based techniques, like multi-modal drag and tilt. Candidates were asked to complete various interaction tasks relevant for most applications on a large, monitor-based, high-resolution tiled wall system. Our study evaluates both user performance and satisfaction, identifying strengths and weaknesses of the researched interaction methods in specific tasks. Results reveal good performance of users in certain tasks when using the new interaction techniques. Even first-time users were able to complete a task faster with the smart phone than with traditional devices. | false | false | [
"Jens Bauer",
"Sebastian Thelen",
"Achim Ebert"
] | [] | [] | [] |
VAST | 2,011 | Exploring agent-based simulations using temporal graphs | 10.1109/VAST.2011.6102469 | Agent-based simulation has become a key technique for modeling and simulating dynamic, complicated behaviors in social and behavioral sciences. Lacking the appropriate tools and support, it is difficult for social scientists to thoroughly analyze the results of these simulations. In this work, we capture the complex relationships between discrete simulation states by visualizing the data as a temporal graph. In collaboration with expert analysts, we identify two graph structures which capture important relationships between pivotal states in the simulation and their inevitable outcomes. Finally, we demonstrate the utility of these structures in the interactive analysis of a large-scale social science simulation of political power in present-day Thailand. | false | false | [
"R. Jordan Crouser",
"Jeremy G. Freeman",
"Remco Chang"
] | [] | [] | [] |
VAST | 2,011 | Exploring proportions: Comparative visualization of categorical data | 10.1109/VAST.2011.6102481 | This poster describes an approach to facilitate comparisons in multi-dimensional categorical data. The key idea is to represent over- or under-proportional relationships explicitly. On an overview level, the visualization of various measures conveys pair-wise relationships between categorical dimensions. For more details, interaction supports to relate a single category to all categories of multiple dimensions. We discuss methods for representing relationships and visualization-driven strategies for ordering dimensions and categories, and we illustrate the approach by means of data from a social survey. | false | false | [
"Harald Piringer",
"Matthias Buchetics"
] | [] | [] | [] |
VAST | 2,011 | Find distance function, hide model inference | 10.1109/VAST.2011.6102478 | Faced with a large, high-dimensional dataset, many turn to data analysis approaches that they understand less well than the domain of their data. An expert's knowledge can be leveraged into many types of analysis via a domain-specific distance function, but creating such a function is not intuitive to do by hand. We have created a system that shows an initial visualization, adapts to user feedback, and produces a distance function as a result. Specifically, we present a multidimensional scaling (MDS) visualization and an iterative feedback mechanism for a user to affect the distance function that informs the visualization without having to adjust the parameters of the visualization directly. An encouraging experimental result suggests that using this tool, data attributes with useless data are given low importance in the distance function. | false | false | [
"Jingjing Liu",
"Eli T. Brown",
"Remco Chang"
] | [] | [] | [] |
VAST | 2,011 | From movement tracks through events to places: Extracting and characterizing significant places from mobility data | 10.1109/VAST.2011.6102454 | We propose a visual analytics procedure for analyzing movement data, i.e., recorded tracks of moving objects. It is oriented to a class of problems where it is required to determine significant places on the basis of certain types of events occurring repeatedly in movement data. The procedure consists of four major steps: (1) event extraction from trajectories; (2) event clustering and extraction of relevant places; (3) spatio-temporal aggregation of events or trajectories; (4) analysis of the aggregated data. All steps are scalable with respect to the amount of the data under analysis. We demonstrate the use of the procedure by example of two real-world problems requiring analysis at different spatial scales. | false | false | [
"Gennady L. Andrienko",
"Natalia V. Andrienko",
"Christophe Hurter",
"Salvatore Rinzivillo",
"Stefan Wrobel"
] | [
"BP"
] | [] | [] |
VAST | 2,011 | G-PARE: A visual analytic tool for comparative analysis of uncertain graphs | 10.1109/VAST.2011.6102442 | There are a growing number of machine learning algorithms which operate on graphs. Example applications for these algorithms include predicting which customers will recommend products to their friends in a viral marketing campaign using a customer network, predicting the topics of publications in a citation network, or predicting the political affiliations of people in a social network. It is important for an analyst to have tools to help compare the output of these machine learning algorithms. In this work, we present G-PARE, a visual analytic tool for comparing two uncertain graphs, where each uncertain graph is produced by a machine learning algorithm which outputs probabilities over node labels. G-PARE provides several different views which allow users to obtain a global overview of the algorithms output, as well as focused views that show subsets of nodes of interest. By providing an adaptive exploration environment, G-PARE guides the users to places in the graph where two algorithms predictions agree and places where they disagree. This enables the user to follow cascades of misclassifications by comparing the algorithms outcome with the ground truth. After describing the features of G-PARE, we illustrate its utility through several use cases based on networks from different domains. | false | false | [
"Hossam Sharara",
"Awalin Sopan",
"Galileo Namata",
"Lise Getoor",
"Lisa Singh"
] | [] | [] | [] |
VAST | 2,011 | Geovisual analytics for cyber security: Adopting the GeoViz Toolkit | 10.1109/VAST.2011.6102491 | For the VAST 2011 Network Security Mini-Challenge, we adopted geovisual analytic methods and applied them in the field of network security. We used the GeoViz Toolkit [1] to represent cyber security events, by fabricating a simple “geography” of several sets of blocks (one for the workstations, one for the servers, and one for the Internet) using ArcGIS 10 (by ESRI - Environmental System Research Institute). Security data was tabulated using Perl scripts to parse the logs in order to create representations of event frequency and where they occurred on the network. The tabulated security data was then added as attributes of the geography. Exploration of the data and subsequent analysis of the meaning and impact of the cyber security events was made possible using the GeoViz Toolkit. | false | false | [
"Nicklaus A. Giacobe",
"Sen Xu"
] | [] | [] | [] |
VAST | 2,011 | Guiding feature subset selection with an interactive visualization | 10.1109/VAST.2011.6102448 | We propose a method for the semi-automated refinement of the results of feature subset selection algorithms. Feature subset selection is a preliminary step in data analysis which identifies the most useful subset of features (columns) in a data table. So-called filter techniques use statistical ranking measures for the correlation of features. Usually a measure is applied to all entities (rows) of a data table. However, the differing contributions of subsets of data entities are masked by statistical aggregation. Feature and entity subset selection are, thus, highly interdependent. Due to the difficulty in visualizing a high-dimensional data table, most feature subset selection algorithms are applied as a black box at the outset of an analysis. Our visualization technique, SmartStripes, allows users to step into the feature subset selection process. It enables the investigation of dependencies and interdependencies between different feature and entity subsets. A user may even choose to control the iterations manually, taking into account the ranking measures, the contributions of different entity subsets, as well as the semantics of the features. | false | false | [
"Thorsten May",
"Andreas Bannach",
"James Davey",
"Tobias Ruppert",
"Jörn Kohlhammer"
] | [] | [] | [] |
VAST | 2,011 | Guiding security analysis through visualization | 10.1109/VAST.2011.6102492 | We present a multiple views visualization for the security data in the VAST 2010 Mini Challenge 2. The visualization is used to monitor log event activity on the network log data included in the challenge. Interactions are provided that allow analysts to investigate suspicious activity and escalate events as needed. Additionally, a database application is used to allow SQL queries for more detailed investigation. | false | false | [
"Lane Harrison",
"Wenwen Dou",
"Aidong Lu",
"William Ribarsky",
"Derek Xiaoyu Wang"
] | [] | [] | [] |
VAST | 2,011 | How locus of control influences compatibility with visualization style | 10.1109/VAST.2011.6102445 | Existing research suggests that individual personality differences are correlated with a user's speed and accuracy in solving problems with different types of complex visualization systems. In this paper, we extend this research by isolating factors in personality traits as well as in the visualizations that could have contributed to the observed correlation. We focus on a personality trait known as “locus of control,” which represents a person's tendency to see themselves as controlled by or in control of external events. To isolate variables of the visualization design, we control extraneous factors such as color, interaction, and labeling, and specifically focus on the overall layout style of the visualizations. We conduct a user study with four visualizations that gradually shift from an indentation metaphor to a containment metaphor and compare the participants' speed, accuracy, and preference with their locus of control. Our findings demonstrate that there is indeed a correlation between the two: participants with an internal locus of control perform more poorly with visualizations that employ a containment metaphor, while those with an external locus of control perform well with such visualizations. We discuss a possible explanation for this relationship based in cognitive psychology and propose that these results can be used to better understand how people use visualizations and how to adapt visual analytics design to an individual user's needs. | false | false | [
"Caroline Ziemkiewicz",
"R. Jordan Crouser",
"Ashley Rye Yauilla",
"Sara L. Su",
"William Ribarsky",
"Remco Chang"
] | [
"HM"
] | [] | [] |
VAST | 2,011 | Interactive data analysis with nSpace2(c) | 10.1109/VAST.2011.6102497 | nSpace2 is an innovative visual analytics tool that was the primary platform used to search, evaluate, and organize the data in the VAST 2011 Mini Challenge #3 dataset. nSpace2 is a web-based tool that is designed to facilitate the back-and-forth flow of the multiple steps of an analysis process, including search, data triage, organization, sense-making, and reporting. This paper describes how nSpace2 was used to assist every step of the analysis process for this VAST challenge. | false | false | [
"Casey M. Canfield",
"David Sheffield"
] | [] | [] | [] |
VAST | 2,011 | Interactive decision making using dissimilarity to visually represented prototypes | 10.1109/VAST.2011.6102451 | To make informed decisions, an expert has to reason with multi-dimensional, heterogeneous data and analysis results of these. Items in such datasets are typically represented by features. However, as argued in cognitive science, features do not yield an optimal space for human reasoning. In fact, humans tend to organize complex information in terms of prototypes or known cases rather than in absolute terms. When confronted with unknown data items, humans assess them in terms of similarity to these prototypical elements. Interestingly, an analogues similarity-to-prototype approach, where prototypes are taken from the data, has been successfully applied in machine learning. Combining such a machine learning approach with human prototypical reasoning in a Visual Analytics context requires to integrate similarity-based classification with interactive visualizations. To that end, the data prototypes should be visually represented to trigger direct associations to cases familiar to the domain experts. In this paper, we propose a set of highly interactive visualizations to explore data and classification results in terms of dissimilarities to visually represented prototypes. We argue that this approach not only supports human reasoning processes, but is also suitable to enhance understanding of heterogeneous data. The proposed framework is applied to a risk assessment case study in Forensic Psychiatry. | false | false | [
"Gosia Migut",
"Jan C. van Gemert",
"Marcel Worring"
] | [] | [] | [] |
VAST | 2,011 | Interactive visual comparison of multiple trees | 10.1109/VAST.2011.6102439 | Traditionally, the visual analysis of hierarchies, respectively, trees, is conducted by focusing on one given hierarchy. However, in many research areas multiple, differing hierarchies need to be analyzed simultaneously in a comparative way - in particular to highlight differences between them, which sometimes can be subtle. A prominent example is the analysis of so-called phylogenetic trees in biology, reflecting hierarchical evolutionary relationships among a set of organisms. Typically, the analysis considers multiple phylogenetic trees, either to account for statistical significance or for differences in derivation of such evolutionary hierarchies; for example, based on different input data, such as the 16S ribosomal RNA and protein sequences of highly conserved enzymes. The simultaneous analysis of a collection of such trees leads to more insight into the evolutionary process. We introduce a novel visual analytics approach for the comparison of multiple hierarchies focusing on both global and local structures. A new tree comparison score has been elaborated for the identification of interesting patterns. We developed a set of linked hierarchy views showing the results of automatic tree comparison on various levels of details. This combined approach offers detailed assessment of local and global tree similarities. The approach was developed in close cooperation with experts from the evolutionary biology domain. We apply it to a phylogenetic data set on bacterial ancestry, demonstrating its application benefit. | false | false | [
"Sebastian Bremm",
"Tatiana von Landesberger",
"Martin Hess",
"Tobias Schreck",
"Philipp Weil",
"Kay Hamacher"
] | [] | [] | [] |
VAST | 2,011 | Jigsaw to save vastopolis | 10.1109/VAST.2011.6102496 | This article describes our analytic process and experience of using the Jigsaw system in working on the VAST 2011 Mini Challenge 3. We describe how we extracted and worked with entities from the documents, and how Jigsaw's computational analysis capabilities and visualizations scaffolded the investigation. Based on our experiences, we discuss desirable features that would enhance the analytic power of Jigsaw. | false | false | [
"Elizabeth Braunstein",
"Carsten Görg",
"Zhicheng Liu",
"John T. Stasko"
] | [] | [] | [] |
VAST | 2,011 | KD-photomap: Exploring photographs in space and time | 10.1109/VAST.2011.6102479 | KD-photomap is a web-based visual analytics system for browsing collections of geotagged Flickr photographs in search of interesting pictures, places, and events. Spatial filtering of the data is performed through zooming, moving or searching along the map. Temporal filtering is possible through defining time windows using interactive histograms and calendar controls. Information about the number and spatiotemporal distribution of photos captured in an explored area is continuously provided using various visual cues. | false | false | [
"Iulian Peca",
"Haolin Zhi",
"Katerina Vrotsou",
"Natalia V. Andrienko",
"Gennady L. Andrienko"
] | [] | [] | [] |
VAST | 2,011 | Mapping an epidemic outbreak: Effective analysis and presentation | 10.1109/VAST.2011.6102486 | The microblog challenge presented an opportunity to use commercial software for visual analysis. An epidemic outbreak occurred in the city of Vastopolis, requiring visualizations of symptoms and their spread over time. Using these tools, analysts could successfully identify the outbreak's origin and pattern of dispersion. The maps used to analyze the data and present the results provided clear, easily understood representations, and presented a logical explanation of a complex progression of events. | false | false | [
"Kevin Boone",
"Edward Swing"
] | [] | [] | [] |
VAST | 2,011 | MobileAnalymator: Animating data changes on mobile devices | 10.1109/VAST.2011.6102490 | MobileAnalymator (Mobile Analysis Animator) is a visual analytic system designed to analyze geospatial-temporal data on mobile devices. The system is an Internet based application that allows analysts to work in flexile enviornments at anytime. Its client side is developed by Adobe Flash to animate and interact with data. The server side uses Java and MySQL to query, compute, and serve data. The analyst can run the analytical task from a tablet (or computer) with Internet connection. MobileAnalymator adopted spatial and temporal autocorrelations in the interface design and integrated tangible interaction in the navigation to support analysis process. | false | false | [
"Victor Y. Chen",
"Cheryl Z. Qian",
"Li Zhang"
] | [] | [] | [] |
VAST | 2,011 | Network-based visual analysis of tabular data | 10.1109/VAST.2011.6102440 | Tabular data are pervasive. Although tables often describe multivariate data without explicit network semantics, it may be advantageous to explore the data modeled as a graph or network for analysis. Even when a given table design conveys some static network semantics, analysts may want to look at multiple networks from different perspectives, at different levels of abstraction, and with different edge semantics. We present a system called Ploceus that offers a general approach for performing multi-dimensional and multi-level network-based visual analysis on multivariate tabular data. Powered by an underlying relational algebraic framework, Ploceus supports flexible construction and transformation of networks through a direct manipulation interface, and integrates dynamic network manipulation with visual exploration for a seamless analytic experience. | false | false | [
"Zhicheng Liu",
"Shamkant B. Navathe",
"John T. Stasko"
] | [
"HM"
] | [] | [] |
VAST | 2,011 | Observation-level interaction with statistical models for visual analytics | 10.1109/VAST.2011.6102449 | In visual analytics, sensemaking is facilitated through interactive visual exploration of data. Throughout this dynamic process, users combine their domain knowledge with the dataset to create insight. Therefore, visual analytic tools exist that aid sensemaking by providing various interaction techniques that focus on allowing users to change the visual representation through adjusting parameters of the underlying statistical model. However, we postulate that the process of sensemaking is not focused on a series of parameter adjustments, but instead, a series of perceived connections and patterns within the data. Thus, how can models for visual analytic tools be designed, so that users can express their reasoning on observations (the data), instead of directly on the model or tunable parameters? Observation level (and thus “observation”) in this paper refers to the data points within a visualization. In this paper, we explore two possible observation-level interactions, namely exploratory and expressive, within the context of three statistical methods, Probabilistic Principal Component Analysis (PPCA), Multidimensional Scaling (MDS), and Generative Topographic Mapping (GTM). We discuss the importance of these two types of observation level interactions, in terms of how they occur within the sensemaking process. Further, we present use cases for GTM, MDS, and PPCA, illustrating how observation level interaction can be incorporated into visual analytic tools. | false | false | [
"Alex Endert",
"Chao Han",
"Dipayan Maiti",
"Leanna House",
"Scotland Leman",
"Chris North 0001"
] | [] | [] | [] |
VAST | 2,011 | Obvious: A meta-toolkit to encapsulate information visualization toolkits - One toolkit to bind them all | 10.1109/VAST.2011.6102446 | This article describes “Obvious”: a meta-toolkit that abstracts and encapsulates information visualization toolkits implemented in the Java language. It intends to unify their use and postpone the choice of which concrete toolkit(s) to use later-on in the development of visual analytics applications. We also report on the lessons we have learned when wrapping popular toolkits with Obvious, namely Prefuse, the InfoVis Toolkit, partly Improvise, JUNG and other data management libraries. We show several examples on the uses of Obvious, how the different toolkits can be combined, for instance sharing their data models. We also show how Weka and Rapid-Miner, two popular machine-learning toolkits, have been wrapped with Obvious and can be used directly with all the other wrapped toolkits. We expect Obvious to start a co-evolution process: Obvious is meant to evolve when more components of Information Visualization systems will become consensual. It is also designed to help information visualization systems adhere to the best practices to provide a higher level of interoperability and leverage the domain of visual analytics. | false | false | [
"Jean-Daniel Fekete",
"Pierre-Luc Hemery",
"Thomas Baudel",
"Jo Wood"
] | [] | [] | [] |
VAST | 2,011 | Orion: A system for modeling, transformation and visualization of multidimensional heterogeneous networks | 10.1109/VAST.2011.6102441 | The study of complex activities such as scientific production and software development often require modeling connections among heterogeneous entities including people, institutions and artifacts. Despite numerous advances in algorithms and visualization techniques for understanding such social networks, the process of constructing network models and performing exploratory analysis remains difficult and time-consuming. In this paper we present Orion, a system for interactive modeling, transformation and visualization of network data. Orion's interface enables the rapid manipulation of large graphs-including the specification of complex linking relationships-using simple drag-and-drop operations with desired node types. Orion maps these user interactions to statements in a declarative workflow language that incorporates both relational operators (e.g., selection, aggregation and joins) and network analytics (e.g., centrality measures). We demonstrate how these features enable analysts to flexibly construct and compare networks in domains such as online health communities, academic collaboration and distributed software development. | false | false | [
"Jeffrey Heer",
"Adam Perer"
] | [] | [] | [] |
VAST | 2,011 | ParallelTopics: A probabilistic approach to exploring document collections | 10.1109/VAST.2011.6102461 | Scalable and effective analysis of large text corpora remains a challenging problem as our ability to collect textual data continues to increase at an exponential rate. To help users make sense of large text corpora, we present a novel visual analytics system, Parallel-Topics, which integrates a state-of-the-art probabilistic topic model Latent Dirichlet Allocation (LDA) with interactive visualization. To describe a corpus of documents, ParallelTopics first extracts a set of semantically meaningful topics using LDA. Unlike most traditional clustering techniques in which a document is assigned to a specific cluster, the LDA model accounts for different topical aspects of each individual document. This permits effective full text analysis of larger documents that may contain multiple topics. To highlight this property of the model, ParallelTopics utilizes the parallel coordinate metaphor to present the probabilistic distribution of a document across topics. Such representation allows the users to discover single-topic vs. multi-topic documents and the relative importance of each topic to a document of interest. In addition, since most text corpora are inherently temporal, ParallelTopics also depicts the topic evolution over time. We have applied ParallelTopics to exploring and analyzing several text corpora, including the scientific proposals awarded by the National Science Foundation and the publications in the VAST community over the years. To demonstrate the efficacy of ParallelTopics, we conducted several expert evaluations, the results of which are reported in this paper. | false | false | [
"Wenwen Dou",
"Derek Xiaoyu Wang",
"Remco Chang",
"William Ribarsky"
] | [] | [] | [] |
VAST | 2,011 | Perception-based visual quality measures | 10.1109/VAST.2011.6102437 | In recent years diverse quality measures to support the exploration of high-dimensional data sets have been proposed. Such measures can be very useful to rank and select information-bearing projections of very high dimensional data, when the visual exploration of all possible projections becomes unfeasible. But even though a ranking of the low dimensional projections may support the user in the visual exploration task, different measures deliver different distances between the views that do not necessarily match the expectations of human perception. As an alternative solution, we propose a perception-based approach that, similar to the existing measures, can be used to select information bearing projections of the data. Specifically, we construct a perceptual embedding for the different projections based on the data from a psychophysics study and multi-dimensional scaling. This embedding together with a ranking function is then used to estimate the value of the projections for a specific user task in a perceptual sense. | false | false | [
"Georgia Albuquerque",
"Martin Eisemann",
"Marcus A. Magnor"
] | [] | [] | [] |
VAST | 2,011 | Pexel and heatmap visual analysis of multidimensional gun/homicide data | 10.1109/VAST.2011.6102482 | We present a visual analysis tool for mining correlations in county-level, multidimensional gun/homicide data. The tool uses 2D pexels, heatmaps, linked-views, dynamic queries and details-on-demand to analyze annual county-level data on firearm homicide rates and gun availability, as well as various socio-demographic measures. A statistical significance filter was implemented as a visual means to validate exploratory hypotheses. Results from expert evaluations indicate that our methods outperform typical graphical techniques used by statisticians, such as bar graphs, scatterplots and residual plots, to show spatial and temporal relationships. Our visualization has the potential to convey the impact of gun availability on firearm homicides to the public health arena and the general public. | false | false | [
"Scott D. Rothenberger",
"John E. Wenskovitch",
"G. Elisabeta Marai"
] | [] | [] | [] |
VAST | 2,011 | Pointwise local pattern exploration for sensitivity analysis | 10.1109/VAST.2011.6102450 | Sensitivity analysis is a powerful method for discovering the significant factors that contribute to targets and understanding the interaction between variables in multivariate datasets. A number of sensitivity analysis methods fall into the class of local analysis, in which the sensitivity is defined as the partial derivatives of a target variable with respect to a group of independent variables. Incorporating sensitivity analysis in visual analytic tools is essential for multivariate phenomena analysis. However, most current multivariate visualization techniques do not allow users to explore local patterns individually for understanding the sensitivity from a pointwise view. In this paper, we present a novel pointwise local pattern exploration system for visual sensitivity analysis. Using this system, analysts are able to explore local patterns and the sensitivity at individual data points, which reveals the relationships between a focal point and its neighbors. During exploration, users are able to interactively change the derivative coefficients to perform sensitivity analysis based on different requirements as well as their domain knowledge. Each local pattern is assigned an outlier factor, so that users can quickly identify anomalous local patterns that do not conform with the global pattern. Users can also compare the local pattern with the global pattern both visually and statistically. Finally, the local pattern is integrated into the original attribute space using color mapping and jittering, which reveals the distribution of the partial derivatives. Case studies with real datasets are used to investigate the effectiveness of the visualizations and interactions. | false | false | [
"Zhenyu Guo",
"Matthew O. Ward",
"Elke A. Rundensteiner",
"Carolina Ruiz"
] | [] | [] | [] |
VAST | 2,011 | PORGY: Interactive and visual reasoning with graph rewriting systems | 10.1109/VAST.2011.6102480 | Graph rewriting systems are easily described and explained. They can be seen as a game where one iterates transformation rules on an initial graph, until some condition is met. A rule describes a local pattern (i.e. a subgraph) that must be identified in a graph and specifies how to transform this subgraph. The graph rewriting formalism is at the same time extremely rich and complex, making the study of a model expressed in terms of graph rewriting quite challenging. For instance, predicting whether rules can be applied in any order is often difficult. When modelling complex systems, graphical formalisms have clear advantages: they are more intuitive and make it easier to visualize a system and convey intuitions about it. This work focuses on the design of an interactive visual graph rewriting system which supports graphical manipulations and computation to reason and simulate on a system. PORGY has been designed based on regular exchanges with graph rewriting systems experts and users over the past three years. The design choices relied on a careful methodology inspired from Munzner's nested process model for visualization design and validation [4]. | false | false | [
"Bruno Pinaud",
"Jonathan Dubois",
"Guy Melançon"
] | [] | [] | [] |
VAST | 2,011 | Query-based coordinated multiple views with Feature Similarity Space for visual analysis of MRI repositories | 10.1109/VAST.2011.6102467 | It is a laborious process to quantify relationship patterns within a feature-rich archive. For example, understanding the degree of neuroanatomical similarity between the scanned subjects of a Magnetic Resonance Imaging (MRI) repository is a nontrivial task. In this work we present a Coordinated Multiple View (CMV) system for visually analyzing collections of feature-rich datasets. A query-based user interface operates on a feature-respective data scheme, and is geared towards domain experts that are non-specialists in informatics and analytics. We employ multi-dimensional scaling (MDS) to project feature surface representations into three-dimensions, where proximity in location is proportional to the feature similarity. Through query feedback and environment navigation, the user groups clusters that exhibit probable trends across feature and attribute. The system provides supervised classification methods for determining attribute classes within the user selected groups. Finally, using visual or analytical feature-wise exploration the user determines intra-group feature commonality. | false | false | [
"Ian Bowman",
"Shantanu H. Joshi",
"John D. Van Horn"
] | [] | [] | [] |
VAST | 2,011 | Reasonable abstractions: Semantics for dynamic data visualization | 10.1109/VAST.2011.6102468 | Chi showed how to treat visualization programing models abstractly. This provided a firm theoretical basis for the data-state model of visualization. However, Chi's models did not look deeper into fine-grained program properties, such as execution semantics. We present conditionally deterministic and resource bounded semantics for the data flow model of visualization based on E-FRP. These semantics are used in the Stencil system to move between data state and data flow execution, build task-based parallelism, and build complex analysis chains for dynamic data. This initial work also shows promise for other complex operators, compilation techniques to enable efficient use of time and space, and mixing task and data parallelism. | false | false | [
"Joseph A. Cottam",
"Andrew Lumsdaine"
] | [] | [] | [] |
VAST | 2,011 | SAVE: Sensor anomaly visualization engine | 10.1109/VAST.2011.6102458 | Diagnosing a large-scale sensor network is a crucial but challenging task. Particular challenges include the resource and bandwidth constraints on sensor nodes, the spatiotemporally dynamic network behaviors, and the lack of accurate models to understand such behaviors in a hostile environment. In this paper, we present the Sensor Anomaly Visualization Engine (SAVE), a system that fully leverages the power of both visualization and anomaly detection analytics to guide the user to quickly and accurately diagnose sensor network failures and faults. SAVE combines customized visualizations over separate sensor data facets as multiple coordinated views. Temporal expansion model, correlation graph and dynamic projection views are proposed to effectively interpret the topological, correlational and dimensional sensor data dynamics and their anomalies. Through a case study with real-world sensor network system and administrators, we demonstrate that SAVE is able to help better locate the system problem and further identify the root cause of major sensor network failure scenarios. | false | false | [
"Lei Shi 0002",
"Qi Liao 0002",
"Yuan He 0004",
"Rui Li 0047",
"Aaron Striegel",
"Zhong Su"
] | [] | [] | [] |
VAST | 2,011 | ScatterBlogs: Geo-spatial document analysis | 10.1109/VAST.2011.6102488 | We presented Scatterblogs, a system for microblog analysis that seamlessly integrates search backend and visual frontend. It provides powerful, automatic algorithms for detecting spatio-temporal `anomalies' within blog entries as well as corresponding visual representations and interaction facilities for inspecting anomalies or exploiting them in further analytic steps. Apart from that, we consider the system's combinatoric facilities for building complex hypotheses from temporal, spatial, and content-related aspects an important feature. This was the key for creating a cross-checked analysis for MC1. | false | false | [
"Harald Bosch",
"Dennis Thom",
"Michael Wörner 0001",
"Steffen Koch 0001",
"Edwin Puttmann",
"Dominik Jäckle",
"Thomas Ertl"
] | [] | [] | [] |
VAST | 2,011 | SensePlace2: GeoTwitter analytics support for situational awareness | 10.1109/VAST.2011.6102456 | Geographically-grounded situational awareness (SA) is critical to crisis management and is essential in many other decision making domains that range from infectious disease monitoring, through regional planning, to political campaigning. Social media are becoming an important information input to support situational assessment (to produce awareness) in all domains. Here, we present a geovisual analytics approach to supporting SA for crisis events using one source of social media, Twitter. Specifically, we focus on leveraging explicit and implicit geographic information for tweets, on developing place-time-theme indexing schemes that support overview+detail methods and that scale analytical capabilities to relatively large tweet volumes, and on providing visual interface methods to enable understanding of place, time, and theme components of evolving situations. Our approach is user-centered, using scenario-based design methods that include formal scenarios to guide design and validate implementation as well as a systematic claims analysis to justify design choices and provide a framework for future testing. The work is informed by a structured survey of practitioners and the end product of Phase-I development is demonstrated / validated through implementation in SensePlace2, a map-based, web application initially focused on tweets but extensible to other media. | false | false | [
"Alan M. MacEachren",
"Anuj R. Jaiswal",
"Anthony C. Robinson",
"Scott Pezanowski",
"Alexander Savelyev",
"Prasenjit Mitra",
"Xiao Zhang 0019",
"Justine I. Blanford"
] | [
"TT"
] | [] | [] |
VAST | 2,011 | Supporting effective common ground construction in Asynchronous Collaborative Visual Analytics | 10.1109/VAST.2011.6102447 | Asynchronous Collaborative Visual Analytics (ACVA) leverages group sensemaking by releasing the constraints on when, where, and who works collaboratively. A significant task to be addressed before ACVA can reach its full potential is effective common ground construction, namely the process in which users evaluate insights from individual work to develop a shared understanding of insights and collectively pool them. This is challenging due to the lack of instant communication and scale of collaboration in ACVA. We propose a novel visual analytics approach that automatically gathers, organizes, and summarizes insights to form common ground with reduced human effort. The rich set of visualization and interaction techniques provided in our approach allows users to effectively and flexibly control the common ground construction and review, explore, and compare insights in detail. A working prototype of the approach has been implemented. We have conducted a case study and a user study to demonstrate its effectiveness. | false | false | [
"Yang Chen",
"Jamal Alsakran",
"Scott Barlowe",
"Jing Yang 0001",
"Ye Zhao 0003"
] | [] | [] | [] |
VAST | 2,011 | TreeVersity: Comparing tree structures by topology and node's attributes differences | 10.1109/VAST.2011.6102471 | It is common to classify data in hierarchies, they provide a comprehensible way of understanding big amounts of data. From budgets to organizational charts or even the stock market, trees are everywhere and people find them easy to use. However when analysts need to compare two versions of the same tree structure, or two related taxonomies, the task is not so easy. Much work has been done on this topic, but almost all of it has been restricted to either compare the trees by topology, or by the node attribute values. With this project we are proposing TreeVersity, a framework for comparing tree structures, both by structural changes and by differences in the node attributes. This paper is based on our previous work on comparing traffic agencies using LifeFlow [1, 2] and on a first prototype of TreeVersity. | false | false | [
"John Alexis Guerra Gómez",
"Audra Buck-Coleman",
"Catherine Plaisant",
"Ben Shneiderman"
] | [] | [] | [] |
VAST | 2,011 | Using random projections to identify class-separating variables in high-dimensional spaces | 10.1109/VAST.2011.6102465 | Projection Pursuit has been an effective method for finding interesting low-dimensional (usually 2D) projections in multidimensional spaces. Unfortunately, projection pursuit is not scalable to high-dimensional spaces. We introduce a novel method for approximating the results of projection pursuit to find class-separating views by using random projections. We build an analytic visualization platform based on this algorithm that is scalable to extremely large problems. Then, we discuss its extension to the recognition of other noteworthy configurations in high-dimensional spaces. | false | false | [
"Anushka Anand",
"Leland Wilkinson",
"Tommy Dang"
] | [] | [] | [] |
VAST | 2,011 | Visual analysis of route diversity | 10.1109/VAST.2011.6102455 | Route suggestion is an important feature of GPS navigation systems. Recently, Microsoft T-drive has been enabled to suggest routes chosen by experienced taxi drivers for given source/destination pairs in given time periods, which often take less time than the routes calculated according to distance. However, in real environments, taxi drivers may use different routes to reach the same destination, which we call route diversity. In this paper we first propose a trajectory visualization method that examines the regions where the diversity exists and then develop several novel visualization techniques to display the high dimensional attributes and statistics associated with different routes to help users analyze diversity patterns. Our techniques have been applied to the real trajectory data of thousands of taxis and some interesting findings about route diversity have been obtained. We further demonstrate that our system can be used not only to suggest better routes for drivers but also to analyze traffic bottlenecks for transportation management. | false | false | [
"He Liu",
"Yuan Gao",
"Lu Lu",
"Siyuan Liu",
"Huamin Qu",
"Lionel M. Ni"
] | [] | [] | [] |
VAST | 2,011 | Visual analytic roadblocks for novice investigators | 10.1109/VAST.2011.6102435 | We have observed increasing interest in visual analytics tools and their applications in investigative analysis. Despite the growing interest and substantial studies regarding the topic, understanding the major roadblocks of using such tools from novice users' perspectives is still limited. Therefore, we attempted to identify such “visual analytic roadblocks” for novice users in an investigative analysis scenario. To achieve this goal, we reviewed the existing models, theories, and frameworks that could explain the cognitive processes of human-visualization interaction in investigative analysis. Then, we conducted a qualitative experiment with six novice participants, using a slightly modified version of pair analytics, and analyzed the results through the open-coding method. As a result, we came up with four visual analytic roadblocks and explained these roadblocks using existing cognitive models and theories. We also provided design suggestions to overcome these roadblocks. | false | false | [
"Bum Chul Kwon",
"Brian D. Fisher",
"Ji Soo Yi"
] | [] | [] | [] |
VAST | 2,011 | Visual analytical approaches to evaluating uncertainty and bias in crowd sourced crisis information | 10.1109/VAST.2011.6102470 | Concerns about verification mean the humanitarian community are reluctant to use information collected during crisis events, even though such information could potentially enhance the response effort. Consequently, a program of research is presented that aims to evaluate the degree to which uncertainty and bias are found in public collections of incident reports gathered during crisis events. These datasets exemplify a class whose members have spatial and temporal attributes, are gathered from heterogeneous sources, and do not have readily available attribution information. An interactive software prototype, and existing software, are applied to a dataset related to the current armed conflict in Libya to identify `intrinsic' characteristics against which uncertainty and bias can be evaluated. Requirements on the prototype are identified, which in time will be expanded into full research objectives. | false | false | [
"Iain Dillingham",
"Jason Dykes",
"Jo Wood"
] | [] | [] | [] |
VAST | 2,011 | Visual analytics decision support environment for epidemic modeling and response evaluation | 10.1109/VAST.2011.6102457 | In modeling infectious diseases, scientists are studying the mechanisms by which diseases spread, predicting the future course of the outbreak, and evaluating strategies applied to control an epidemic. While recent work has focused on accurately modeling disease spread, less work has been performed in developing interactive decision support tools for analyzing the future course of the outbreak and evaluating potential disease mitigation strategies. The absence of such tools makes it difficult for researchers, analysts and public health officials to evaluate response measures within outbreak scenarios. As such, our research focuses on the development of an interactive decision support environment in which users can explore epidemic models and their impact. This environment provides a spatiotemporal view where users can interactively utilize mitigative response measures and observe the impact of their decision over time. Our system also provides users with a linked decision history visualization and navigation tool that support the simultaneous comparison of mortality and infection rates corresponding to different response measures at different points in time. | false | false | [
"Shehzad Afzal",
"Ross Maciejewski",
"David S. Ebert"
] | [] | [] | [] |
VAST | 2,011 | Visual analytics of terrorist activities related to epidemics | 10.1109/VAST.2011.6102498 | The task of the VAST 2011 Grand Challenge was to investigate potential terrorist activities and their relation to the spread of an epidemic. Three different data sets were provided as part of three Mini Challenges (MCs). MC 1 was about analyzing geo-tagged microblogging (Twitter) messages to characterize the spread of an epidemic. MC 2 required analyzing threats to a computer network using a situational awareness approach. In MC 3 possible criminal and terrorist activities were to be analyzed based on a collection of news articles. To solve the Grand Challenge, insight from each of the individual MCs had to be integrated appropriately. | false | false | [
"Enrico Bertini",
"Juri Buchmüller",
"Fabian Fischer 0001",
"Stephan Huber",
"Thomas Lindemeier",
"Fabian Maass",
"Florian Mansmann",
"Thomas Ramm",
"Michael Regenscheit",
"Christian Rohrdantz",
"Christian Scheible",
"Tobias Schreck",
"Stephan Sellien",
"Florian Stoffel",
"Mark Tautzenberger",
"Matthias Zieker",
"Daniel A. Keim"
] | [] | [] | [] |
VAST | 2,011 | Visual sentiment analysis on twitter data streams | 10.1109/VAST.2011.6102472 | Twitter currently receives about 190 million tweets (small text-based Web posts) a day, in which people share their comments regarding a wide range of topics. A large number of tweets include opinions about products and services. However, with Twitter being a relatively new phenomenon, these tweets are underutilized as a source for evaluating customer sentiment. To explore high-volume twitter data, we introduce three novel time-based visual sentiment analysis techniques: (1) topic-based sentiment analysis that extracts, maps, and measures customer opinions; (2) stream analysis that identifies interesting tweets based on their density, negativity, and influence characteristics; and (3) pixel cell-based sentiment calendars and high density geo maps that visualize large volumes of data in a single view. We applied these techniques to a variety of twitter data, (e.g., movies, amusement parks, and hotels) to show their distribution and patterns, and to identify influential opinions. | false | false | [
"Ming C. Hao",
"Christian Rohrdantz",
"Halldór Janetzko",
"Umeshwar Dayal",
"Daniel A. Keim",
"Lars-Erik Haug",
"Meichun Hsu"
] | [] | [] | [] |
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