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 |
|---|---|---|---|---|---|---|---|---|---|---|
VAST | 2,009 | Palantir: A visualization platform for real-world analysis | 10.1109/VAST.2009.5334462 | Palantir is an analytic platform currently used worldwide by both governmental and financial analysts. This paper provides a brief overview of the platform, examines our 2009 IEEE VAST Challenge submission, and highlights several key analytic and visualization features we used in our analysis. | false | false | [
"Brandon Wright",
"Jason Payne",
"Matthew Steckman",
"Scott Stevson"
] | [] | [] | [] |
VAST | 2,009 | Parallel Tag Clouds to explore and analyze faceted text corpora | 10.1109/VAST.2009.5333443 | Do court cases differ from place to place? What kind of picture do we get by looking at a country's collection of law cases? We introduce parallel tag clouds: a new way to visualize differences amongst facets of very large metadata-rich text corpora. We have pointed parallel tag clouds at a collection of over 600,000 US Circuit Court decisions spanning a period of 50 years and have discovered regional as well as linguistic differences between courts. The visualization technique combines graphical elements from parallel coordinates and traditional tag clouds to provide rich overviews of a document collection while acting as an entry point for exploration of individual texts. We augment basic parallel tag clouds with a details-in-context display and an option to visualize changes over a second facet of the data, such as time. We also address text mining challenges such as selecting the best words to visualize, and how to do so in reasonable time periods to maintain interactivity. | false | false | [
"Christopher Collins 0001",
"Fernanda B. Viégas",
"Martin Wattenberg"
] | [
"TT"
] | [] | [] |
VAST | 2,009 | Poster: Icexplorer: Studying Great Lakes Ice cover | 10.1109/VAST.2009.5333082 | IceXplorer is a tool for analyzing variations in ice cover on Lake Erie. It enhances the data and pre-packaged analysis currently available in the great lakes ice atlas and serves as an example of a small, focused application where simple but carefully-chosen visualizations, interaction techniques, and automated data analysis are combined to create an effective tool for advancing scientific research. | false | false | [
"Stina S. Bridgeman"
] | [] | [] | [] |
VAST | 2,009 | Poster: Visual prediction of time series | 10.1109/VAST.2009.5333420 | Many well-known time series prediction methods have been used daily by analysts making decisions. To reach a good prediction, we introduce several new visual analysis techniques of smoothing, multi-scaling, and weighted average with the involvement of human expert knowledge. We combine them into a well-fitted method to perform prediction. We have applied this approach to predict resource consumption in data center for next day planning. | false | false | [
"Ming C. Hao",
"Halldór Janetzko",
"Ratnesh K. Sharma",
"Umeshwar Dayal",
"Daniel A. Keim",
"Malú Castellanos"
] | [] | [] | [] |
VAST | 2,009 | ProcessLine: Visualizing time-series data in process industry | 10.1109/VAST.2009.5333421 | In modern process industry, it is often difficult to analyze a manufacture process due to its numerous time-series data. Analysts wish to not only interpret the evolution of data over time in a working procedure, but also examine the changes in the whole production process through time. To meet such analytic requirements, we have developed ProcessLine, an interactive visualization tool for a large amount of time-series data in process industry. The data are displayed in a fisheye timeline. ProcessLine provides good overviews for the whole production process and details for the focused working procedure. A preliminary user study using beer industry production data has shown that the tool is effective. | false | false | [
"XiongFei Luo",
"Hongan Wang",
"Feng Tian 0001",
"Wei Liu 0023",
"Dongxing Teng",
"Guozhong Dai"
] | [] | [] | [] |
VAST | 2,009 | Professional analysts using a large, high-resolution display | 10.1109/VAST.2009.5332485 | Professional cyber analysts were observed as they attempted to solve the VAST 2009 Traffic Mini Challenge using basic visualization tools and a large, high-resolution display. We discuss some of the lessons we learned about how analysts actually work and potential roles for visualization and large, high-resolution displays. | false | false | [
"Alex Endert",
"Christopher Andrews",
"Glenn A. Fink",
"Chris North 0001"
] | [] | [] | [] |
VAST | 2,009 | Proximity-based visualization of movement trace data | 10.1109/VAST.2009.5332593 | The increasing availability of motion sensors and video cameras in living spaces has made possible the analysis of motion patterns and collective behavior in a number of situations. The visualization of this movement data, however, remains a challenge. Although maintaining the actual layout of the data space is often desirable, direct visualization of movement traces becomes cluttered and confusing as the spatial distribution of traces may be disparate and uneven. We present proximity-based visualization as a novel approach to the visualization of movement traces in an abstract space rather than the given spatial layout. This abstract space is obtained by considering proximity data, which is computed as the distance between entities and some number of important locations. These important locations can range from a single fixed point, to a moving point, several points, or even the proximities between the entities themselves. This creates a continuum of proximity spaces, ranging from the fixed absolute reference frame to completely relative reference frames. By combining these abstracted views with the concrete spatial views, we provide a way to mentally map the abstract spaces back to the real space. We demonstrate the effectiveness of this approach, and its applicability to visual analytics problems such as hazard prevention, migration patterns, and behavioral studies. | false | false | [
"Tarik Crnovrsanin",
"Chris Muelder",
"Carlos D. Correa",
"Kwan-Liu Ma"
] | [] | [] | [] |
VAST | 2,009 | Reordered tilebars for visual text exploration | 10.1109/VAST.2009.5333436 | The classic TileBars paradigm has been used to show distribution information of query terms in full-text documents. However, when the number of query terms becomes large, it is not an easy task for users to comprehend their distribution within certain parts of a document. In this paper, we present a novel approach to improve the visual presentation of TileBars, in which barycenter heuristic for bigraph crossing minimization is used to reorder TileBars elements. The reordered TileBars can be demonstrated to provide users with better focus and navigation while exploring text documents. | false | false | [
"VinhTuan Thai",
"Siegfried Handschuh"
] | [] | [] | [] |
VAST | 2,009 | Solving the traffic and flitter challenges with tulip | 10.1109/VAST.2009.5334456 | We present our visualization systems and findings for the badge and network traffic as well as the social network and geospatial challenges of the 2009 VAST contest. The summary starts by presenting an overview of our time series encoding of badge information and network traffic. Our findings suggest that employee 30 may be of interest. In the second part of the paper, we describe our system for finding subgraphs in the social network subject to degree constraints. Subsequently, we present our most likely candidate network which is similar to scenario B. | false | false | [
"Paolo Simonetto",
"Pierre-Yves Koenig",
"Faraz Zaidi",
"Daniel Archambault",
"Frédéric Gilbert 0001",
"Trung-Tien Phan-Quang",
"Morgan Mathiaut",
"Antoine Lambert",
"Jonathan Dubois",
"Ronan Sicre",
"Mathieu Brulin",
"Rémy Vieux",
"Guy Melançon"
] | [] | [] | [] |
VAST | 2,009 | SpRay: A visual analytics approach for gene expression data | 10.1109/VAST.2009.5333911 | We present a new application, SpRay, designed for the visual exploration of gene expression data. It is based on an extension and adaption of parallel coordinates to support the visual exploration of large and high-dimensional datasets. In particular, we investigate the visual analysis of gene expression data as generated by micro-array experiments; We combine refined visual exploration with statistical methods to a visual analytics approach that proved to be particularly successful in this application domain. We will demonstrate the usefulness on several multidimensional gene expression datasets from different bioinformatics applications. | false | false | [
"Janko Dietzsch",
"Julian Heinrich",
"Kay Nieselt",
"Dirk Bartz"
] | [] | [] | [] |
VAST | 2,009 | Timeline analysis of undercover activities VAST 2009 traffic mini challenge award: Good analytical technique | 10.1109/VAST.2009.5334460 | Our visualization tool for the VAST 2009 traffic mini challenge, Timeliner, visualizes badge and network traffic data together in a single timeline. The two views of per-employee and per-day with various filtering interactions enable users to analyze easily employees activities at a particular moment of interest as well as their general daily patterns. Using Timeliner, we present several hypotheses for the task at hand and their validation processes, which reveals various aspects of the data. | false | false | [
"Jaegul Choo",
"Emily Fujimoto",
"Hanseung Lee",
"Pedro R. Walteros"
] | [] | [] | [] |
VAST | 2,009 | Two-stage framework for visualization of clustered high dimensional data | 10.1109/VAST.2009.5332629 | In this paper, we discuss dimension reduction methods for 2D visualization of high dimensional clustered data. We propose a two-stage framework for visualizing such data based on dimension reduction methods. In the first stage, we obtain the reduced dimensional data by applying a supervised dimension reduction method such as linear discriminant analysis which preserves the original cluster structure in terms of its criteria. The resulting optimal reduced dimension depends on the optimization criteria and is often larger than 2. In the second stage, the dimension is further reduced to 2 for visualization purposes by another dimension reduction method such as principal component analysis. The role of the second-stage is to minimize the loss of information due to reducing the dimension all the way to 2. Using this framework, we propose several two-stage methods, and present their theoretical characteristics as well as experimental comparisons on both artificial and real-world text data sets. | false | false | [
"Jaegul Choo",
"Shawn Bohn",
"Haesun Park"
] | [] | [] | [] |
VAST | 2,009 | Using projection and 2D plots to visually reveal genetic mechanisms of complex human disorders | 10.1109/VAST.2009.5333917 | Gene mapping is a statistical method used to localize human disease genes to particular regions of the human genome. When performing such analysis, a genetic likelihood space is generated and sampled, which results in a multidimensional scalar field. Researchers are interested in exploring this likelihood space through the use of visualization. Previous efforts at visualizing this space, though, were slow and cumbersome, only showing a small portion of the space at a time, thus requiring the user to keep a mental picture of several views. We have developed a new technique that displays much more data at once by projecting the multidimensional data into several 2D plots. One plot is created for each parameter that shows the change along that parameter. A radial projection is used to create another plot that provides an overview of the high dimensional surface from the perspective of a single point. Linking and brushing between all the plots are used to determine relationships between parameters. We demonstrate our techniques on real world autism data, showing how to visually examine features of the high dimensional space. | false | false | [
"Boonthanome Nouanesengsy",
"Sang-Cheol Seok",
"Han-Wei Shen",
"Veronica J. Vieland"
] | [] | [] | [] |
VAST | 2,009 | VAST 2009 challenge: An insider threat | 10.1109/VAST.2009.5334454 | The 4<sup>th</sup> VAST Challenge centered on a cyber analytics scenario and offered three mini-challenges with datasets of badge and network traffic data, a social network including geospatial information, and security video. Teams could also enter the Grand challenge which combined all three datasets. In this paper, we summarize the dataset, the overall scenario and the questions asked in the challenges. We describe the judging process and new infrastructure developed to manage the submissions and compute accuracy measures in the social network mini challenge. We received 49 entries from 30 teams, and gave 23 different awards to a total of 16 teams. | false | false | [
"Georges G. Grinstein",
"Jean Scholtz",
"Mark A. Whiting",
"Catherine Plaisant"
] | [] | [] | [] |
VAST | 2,009 | VAST 2009 Traffic Mini Challenge: Intuitive analytic information presentation | 10.1109/VAST.2009.5334301 | As a solution to the VAST 2009 Traffic Mini Visualization Challenge, we built the Badge and Network Traffic (BNT) tool to create animations of the events taking place in the embassy. Using the embassy layout, the prox-card and web-access entries and their time-stamps, we animated color-based flagging of events. The BNT tool highlights logical anomalies occuring in the badge and network traffic data with color-coded alerts. Prior to the animated visualization, the tool analyzes data with respect to various aspects using (i) the amount of data transfers, (ii) destination IPs access patterns, (iii) employee's browsing patterns and (iv) employee's entry log into the restricted area. Any abnormality noticed is immediately reported to the user in the form of plots. In this presentation, we list out the various analyses performed and how they were utilized in the visualization. A few screenshots of the tool are provided to illustrate our analytic information presentation. | false | false | [
"Shraddha Agrawal",
"Kollukuduru Sravanthi",
"Soujanya Vadapalli",
"Kamalakar Karlapalem"
] | [] | [] | [] |
VAST | 2,009 | VAST contest dataset use in education | 10.1109/VAST.2009.5333245 | The IEEE Visual Analytics Science and Technology (VAST) Symposium has held a contest each year since its inception in 2006. These events are designed to provide visual analytics researchers and developers with analytic challenges similar to those encountered by professional information analysts. The VAST contest has had an extended life outside of the symposium, however, as materials are being used in universities and other educational settings, either to help teachers of visual analytics-related classes or for student projects. We describe how we develop VAST contest datasets that results in products that can be used in different settings and review some specific examples of the adoption of the VAST contest materials in the classroom. The examples are drawn from graduate and undergraduate courses at Virginia Tech and from the Visual Analytics ldquoSummer Camprdquo run by the National Visualization and Analytics Center in 2008. We finish with a brief discussion on evaluation metrics for education. | false | false | [
"Mark A. Whiting",
"Chris North 0001",
"Alex Endert",
"Jean Scholtz",
"Jereme Haack",
"Carrie Varley",
"James J. Thomas"
] | [] | [] | [] |
VAST | 2,009 | VIDI surveillance - embassy monitoring and oversight system | 10.1109/VAST.2009.5333950 | We hypothesized that potential spies would try to use other employees' terminals in order to not draw attention to themselves. We define one type of suspicious activity as IP use on a terminal when the owner is inside the classified area. We created a timeline visualization of IP usage, overlaid with classified area entrances and exits. The vertical axis divides the timelines into 31 rows, one for each day of the month. The horizontal axis represents the time of day from early morning to late evening. A single employee's entire month is viewed all at once using this visualization. The employee being viewed can be changed using the arrow keys. Every IP event is represented by a vertical bar positioned at the exact time of its appearance. We color the IP events by port number, which is either intranet, HTTP, tomcat, or email, and size the bar based on the outgoing data size. Whenever an employee enters the classified area, a semi-transparent yellow region is drawn until that user exits the classified area. In rare cases when the user double enters, the region is twice as opaque, and in the other rare case where a user leaves the exits without entering, a red region is drawn until the next time the employee enters. The legend key and office diagram showing the current selected employee, highlighted in red, can be seen in the top left-hand corner. | false | false | [
"Chad Jones",
"Michael Ogawa",
"James Shearer",
"Anna Tikhonova",
"Kwan-Liu Ma"
] | [] | [] | [] |
VAST | 2,009 | VIScover: Visualizing, exploring, and analysing structured data | 10.1109/VAST.2009.5333946 | Today's challenging task in intelligent data processing is not to store large volumes of interlinked data but to visualize, explore, and understand its explicit or implicit relationships. Our solution to this is the VIScover system. VIScover combines semantic technologies with interactive exploration and visualization techniques able to analyze large volumes of structured data. We briefly describe our VIScover system and show its potential using the example of the VAST 2009 social network and geospatial data set. | false | false | [
"Thorsten Liebig",
"Olaf Noppens",
"Friedrich W. von Henke"
] | [] | [] | [] |
VAST | 2,009 | Visual analysis of graphs with multiple connected components | 10.1109/VAST.2009.5333893 | In this paper, we present a system for the interactive visualization and exploration of graphs with many weakly connected components. The visualization of large graphs has recently received much research attention. However, specific systems for visual analysis of graph data sets consisting of many components are rare. In our approach, we rely on graph clustering using an extensive set of topology descriptors. Specifically, we use the self-organizing-map algorithm in conjunction with a user-adaptable combination of graph features for clustering of graphs. It offers insight into the overall structure of the data set. The clustering output is presented in a grid containing clusters of the connected components of the input graph. Interactive feature selection and task-tailored data views allow the exploration of the whole graph space. The system provides also tools for assessment and display of cluster quality. We demonstrate the usefulness of our system by application to a shareholder network analysis problem based on a large real-world data set. While so far our approach is applied to weighted directed graphs only, it can be used for various graph types. | false | false | [
"Tatiana von Landesberger",
"Melanie Görner",
"Tobias Schreck"
] | [] | [] | [] |
VAST | 2,009 | Visual knowledge exploration and discovery from different points of view | 10.1109/VAST.2009.5333438 | Complex scenario analysis requires the exploration of multiple hypotheses and supporting evidence for each argument posed. Knowledge-intensive organisations typically analyse large amounts of inter-related, heterogeneous data to retrieve the knowledge this contains and use it to support effective decision-making. We demonstrate the use of interactive graph visualisation to support hierarchical, task-driven, hypothesis investigation. The visual investigative analysis is guided by task and domain ontologies used to capture the structure of the investigation process and the experience gained and knowledge created in previous, related investigations. | false | false | [
"Aba-Sah Dadzie",
"Daniela Petrelli"
] | [] | [] | [] |
VAST | 2,009 | Visual opinion analysis of customer feedback data | 10.1109/VAST.2009.5333919 | Today, online stores collect a lot of customer feedback in the form of surveys, reviews, and comments. This feedback is categorized and in some cases responded to, but in general it is underutilized - even though customer satisfaction is essential to the success of their business. In this paper, we introduce several new techniques to interactively analyze customer comments and ratings to determine the positive and negative opinions expressed by the customers. First, we introduce a new discrimination-based technique to automatically extract the terms that are the subject of the positive or negative opinion (such as price or customer service) and that are frequently commented on. Second, we derive a Reverse-Distance-Weighting method to map the attributes to the related positive and negative opinions in the text. Third, the resulting high-dimensional feature vectors are visualized in a new summary representation that provides a quick overview. We also cluster the reviews according to the similarity of the comments. Special thumbnails are used to provide insight into the composition of the clusters and their relationship. In addition, an interactive circular correlation map is provided to allow analysts to detect the relationships of the comments to other important attributes and the scores. We have applied these techniques to customer comments from real-world online stores and product reviews from web sites to identify the strength and problems of different products and services, and show the potential of our technique. | false | false | [
"Daniela Oelke",
"Ming C. Hao",
"Christian Rohrdantz",
"Daniel A. Keim",
"Umeshwar Dayal",
"Lars-Erik Haug",
"Halldór Janetzko"
] | [] | [] | [] |
VAST | 2,009 | Visualization of uncertainty and analysis of geographical data | 10.1109/VAST.2009.5333965 | A team of five worked on this challenge to identify a possible criminal structure within the Flitter social network. Initially we worked on the problem individually, deliberately not sharing any data, results or conclusions. This maximised the chances of spotting any blunders, unjustified assumptions or inferences and allowed us to triangulate any common conclusions. After an agreed period we shared our results demonstrating the visualization applications we had built and the reasoning behind our conclusions. This sharing of assumptions encouraged us to incorporate uncertainty in our visualization approaches as it became clear that there was a number of possible interpretations of the rules and assumptions governing the challenge. This summary of the work emphasises one of those applications detailing the geographic analysis and uncertainty handling of the network data. | false | false | [
"Jo Wood",
"Aidan Slingsby",
"Naz Khalili-Shavarini",
"Jason Dykes",
"David M. Mountain"
] | [] | [] | [] |
VAST | 2,009 | Visualized subgraph search | 10.1109/VAST.2009.5333968 | We present a visually supported search and browsing system for network-type data, especially a novel module for subgraph search with a GUI to define subgraphs for queries. We describe how this prototype was applied for the Vast Challenge 2009, Flitter Mini Challenge. | false | false | [
"Dóra Erdös",
"Zsolt Fekete",
"András Lukács"
] | [] | [] | [] |
VAST | 2,009 | What's being said near "Martha"? Exploring name entities in literary text collections | 10.1109/VAST.2009.5333248 | A common task in literary analysis is to study characters in a novel or collection. Automatic entity extraction, text analysis and effective user interfaces facilitate character analysis. Using our interface, called POSvis, the scholar uses word clouds and self-organizing graphs to review vocabulary, to filter by part of speech, and to explore the network of characters located near characters under review. Further, visualizations show word usages within an analysis window (i.e. a book chapter), which can be compared with a reference window (i.e. the whole book). We describe the interface and report on an early case study with a humanities scholar. | false | false | [
"Romain Vuillemot",
"Tanya E. Clement",
"Catherine Plaisant",
"Amit Kumar"
] | [] | [] | [] |
VAST | 2,009 | Working memory load as a novel tool for evaluating visual analytics | 10.1109/VAST.2009.5333468 | The current visual analytics literature highlights design and evaluation processes that are highly variable and situation dependent, which raises at least two broad challenges. First, lack of a standardized evaluation criterion leads to costly re-designs for each task and specific user community. Second, this inadequacy in criterion validation raises significant uncertainty regarding visualization outputs and their related decisions, which may be especially troubling in high consequence environments like those of the intelligence community. As an attempt to standardize the ldquoapples and orangesrdquo of the extant situation, we propose the creation of standardized evaluation tools using general principles of human cognition. Theoretically, visual analytics enables the user to see information in a way that should attenuate the user's memory load and increase the user's task-available cognitive resources. By using general cognitive abilities like available working memory resources as our dependent measures, we propose to develop standardized evaluative capabilities that can be generalized across contexts, tasks, and user communities. | false | false | [
"Courtney C. Dornburg",
"Laura E. Matzen",
"Travis L. Bauer",
"Laura A. McNamara"
] | [] | [] | [] |
InfoVis | 2,009 | "Search, Show Context, Expand on Demand": Supporting Large Graph Exploration with Degree-of-Interest | 10.1109/TVCG.2009.108 | A common goal in graph visualization research is the design of novel techniques for displaying an overview of an entire graph. However, there are many situations where such an overview is not relevant or practical for users, as analyzing the global structure may not be related to the main task of the users that have semi-specific information needs. Furthermore, users accessing large graph databases through an online connection or users running on less powerful (mobile) hardware simply do not have the resources needed to compute these overviews. In this paper, we advocate an interaction model that allows users to remotely browse the immediate context graph around a specific node of interest. We show how Furnas' original degree of interest function can be adapted from trees to graphs and how we can use this metric to extract useful contextual subgraphs, control the complexity of the generated visualization and direct users to interesting datapoints in the context. We demonstrate the effectiveness of our approach with an exploration of a dense online database containing over 3 million legal citations. | false | false | [
"Frank van Ham",
"Adam Perer"
] | [] | [] | [] |
InfoVis | 2,009 | A Comparison of User-Generated and Automatic Graph Layouts | 10.1109/TVCG.2009.109 | The research presented in this paper compares user-generated and automatic graph layouts. Following the methods suggested by van Ham et al. (2008), a group of users generated graph layouts using both multi-touch interaction on a tabletop display and mouse interaction on a desktop computer. Users were asked to optimize their layout for aesthetics and analytical tasks with a social network. We discuss characteristics of the user-generated layouts and interaction methods employed by users in this process. We then report on a web-based study to compare these layouts with the output of popular automatic layout algorithms. Our results demonstrate that the best of the user-generated layouts performed as well as or better than the physics-based layout. Orthogonal and circular automatic layouts were found to be considerably less effective than either the physics-based layout or the best of the user-generated layouts. We highlight several attributes of the various layouts that led to high accuracy and improved task completion time, as well as aspects in which traditional automatic layout methods were unsuccessful for our tasks. | false | false | [
"Tim Dwyer",
"Bongshin Lee",
"Danyel Fisher",
"Kori Inkpen Quinn",
"Petra Isenberg",
"George G. Robertson",
"Chris North 0001"
] | [] | [] | [] |
InfoVis | 2,009 | A Multi-Threading Architecture to Support Interactive Visual Exploration | 10.1109/TVCG.2009.110 | During continuous user interaction, it is hard to provide rich visual feedback at interactive rates for datasets containing millions of entries. The contribution of this paper is a generic architecture that ensures responsiveness of the application even when dealing with large data and that is applicable to most types of information visualizations. Our architecture builds on the separation of the main application thread and the visualization thread, which can be cancelled early due to user interaction. In combination with a layer mechanism, our architecture facilitates generating previews incrementally to provide rich visual feedback quickly. To help avoiding common pitfalls of multi-threading, we discuss synchronization and communication in detail. We explicitly denote design choices to control trade-offs. A quantitative evaluation based on the system VI S P L ORE shows fast visual feedback during continuous interaction even for millions of entries. We describe instantiations of our architecture in additional tools. | false | false | [
"Harald Piringer",
"Christian Tominski",
"Philipp Muigg",
"Wolfgang Berger"
] | [] | [] | [] |
InfoVis | 2,009 | A Nested Model for Visualization Design and Validation | 10.1109/TVCG.2009.111 | We present a nested model for the visualization design and validation with four layers: characterize the task and data in the vocabulary of the problem domain, abstract into operations and data types, design visual encoding and interaction techniques, and create algorithms to execute techniques efficiently. The output from a level above is input to the level below, bringing attention to the design challenge that an upstream error inevitably cascades to all downstream levels. This model provides prescriptive guidance for determining appropriate evaluation approaches by identifying threats to validity unique to each level. We also provide three recommendations motivated by this model: authors should distinguish between these levels when claiming contributions at more than one of them, authors should explicitly state upstream assumptions at levels above the focus of a paper, and visualization venues should accept more papers on domain characterization. | false | false | [
"Tamara Munzner"
] | [
"TT"
] | [] | [] |
InfoVis | 2,009 | ABySS-Explorer: Visualizing Genome Sequence Assemblies | 10.1109/TVCG.2009.116 | One bottleneck in large-scale genome sequencing projects is reconstructing the full genome sequence from the short subsequences produced by current technologies. The final stages of the genome assembly process inevitably require manual inspection of data inconsistencies and could be greatly aided by visualization. This paper presents our design decisions in translating key data features identified through discussions with analysts into a concise visual encoding. Current visualization tools in this domain focus on local sequence errors making high-level inspection of the assembly difficult if not impossible. We present a novel interactive graph display, ABySS-Explorer, that emphasizes the global assembly structure while also integrating salient data features such as sequence length. Our tool replaces manual and in some cases pen-and-paper based analysis tasks, and we discuss how user feedback was incorporated into iterative design refinements. Finally, we touch on applications of this representation not initially considered in our design phase, suggesting the generality of this encoding for DNA sequence data. | false | false | [
"Cydney B. Nielsen",
"Shaun D. Jackman",
"Inanç Birol",
"Steven J. M. Jones"
] | [
"BP"
] | [] | [] |
InfoVis | 2,009 | ActiviTree: Interactive Visual Exploration of Sequences in Event-Based Data Using Graph Similarity | 10.1109/TVCG.2009.117 | The identification of significant sequences in large and complex event-based temporal data is a challenging problem with applications in many areas of today's information intensive society. Pure visual representations can be used for the analysis, but are constrained to small data sets. Algorithmic search mechanisms used for larger data sets become expensive as the data size increases and typically focus on frequency of occurrence to reduce the computational complexity, often overlooking important infrequent sequences and outliers. In this paper we introduce an interactive visual data mining approach based on an adaptation of techniques developed for Web searching, combined with an intuitive visual interface, to facilitate user-centred exploration of the data and identification of sequences significant to that user. The search algorithm used in the exploration executes in negligible time, even for large data, and so no pre-processing of the selected data is required, making this a completely interactive experience for the user. Our particular application area is social science diary data but the technique is applicable across many other disciplines. | false | false | [
"Katerina Vrotsou",
"Jimmy Johansson 0001",
"Matthew Cooper 0001"
] | [] | [] | [] |
InfoVis | 2,009 | Bubble Sets: Revealing Set Relations with Isocontours over Existing Visualizations | 10.1109/TVCG.2009.122 | While many data sets contain multiple relationships, depicting more than one data relationship within a single visualization is challenging. We introduce Bubble Sets as a visualization technique for data that has both a primary data relation with a semantically significant spatial organization and a significant set membership relation in which members of the same set are not necessarily adjacent in the primary layout. In order to maintain the spatial rights of the primary data relation, we avoid layout adjustment techniques that improve set cluster continuity and density. Instead, we use a continuous, possibly concave, isocontour to delineate set membership, without disrupting the primary layout. Optimizations minimize cluster overlap and provide for calculation of the isocontours at interactive speeds. Case studies show how this technique can be used to indicate multiple sets on a variety of common visualizations. | false | false | [
"Christopher Collins 0001",
"Gerald Penn",
"Sheelagh Carpendale"
] | [] | [] | [] |
InfoVis | 2,009 | code_swarm: A Design Study in Organic Software Visualization | 10.1109/TVCG.2009.123 | In May of 2008, we published online a series of software visualization videos using a method called code_swarm. Shortly thereafter, we made the code open source and its popularity took off. This paper is a study of our code swarm application, comprising its design, results and public response. We share our design methodology, including why we chose the organic information visualization technique, how we designed for both developers and a casual audience, and what lessons we learned from our experiment. We validate the results produced by code_swarm through a qualitative analysis and by gathering online user comments. Furthermore, we successfully released the code as open source, and the software community used it to visualize their own projects and shared their results as well. In the end, we believe code_swarm has positive implications for the future of organic information design and open source information visualization practice. | false | false | [
"Michael Ogawa",
"Kwan-Liu Ma"
] | [] | [] | [] |
InfoVis | 2,009 | Comparing Dot and Landscape Spatializations for Visual Memory Differences | 10.1109/TVCG.2009.127 | Spatialization displays use a geographic metaphor to arrange non-spatial data. For example, spatializations are commonly applied to document collections so that document themes appear as geographic features such as hills. Many common spatialization interfaces use a 3-D landscape metaphor to present data. However, it is not clear whether 3-D spatializations afford improved speed and accuracy for user tasks compared to similar 2-D spatializations. We describe a user study comparing users' ability to remember dot displays, 2-D landscapes, and 3-D landscapes for two different data densities (500 vs. 1000 points). Participants' visual memory was statistically more accurate when viewing dot displays and 3-D landscapes compared to 2-D landscapes. Furthermore, accuracy remembering a spatialization was significantly better overall for denser spatializations. Theseresults are of benefit to visualization designers who are contemplating the best ways to present data using spatialization techniques. | false | false | [
"Melanie Tory",
"Colin Swindells",
"Rebecca Dreezer"
] | [] | [] | [] |
InfoVis | 2,009 | Configuring Hierarchical Layouts to Address Research Questions | 10.1109/TVCG.2009.128 | We explore the effects of selecting alternative layouts in hierarchical displays that show multiple aspects of large multivariate datasets, including spatial and temporal characteristics. Hierarchical displays of this type condition a dataset by multiple discrete variable values, creating nested graphical summaries of the resulting subsets in which size, shape and colour can be used to show subset properties. These 'small multiples' are ordered by the conditioning variable values and are laid out hierarchically using dimensional stacking. Crucially, we consider the use of different layouts at different hierarchical levels, so that the coordinates of the plane can be used more effectively to draw attention to trends and anomalies in the data. We argue that these layouts should be informed by the type of conditioning variable and by the research question being explored. We focus on space-filling rectangular layouts that provide data-dense and rich overviews of data to address research questions posed in our exploratory analysis of spatial and temporal aspects of property sales in London. We develop a notation ('HiVE') that describes visualisation and layout states and provides reconfiguration operators, demonstrate its use for reconfiguring layouts to pursue research questions and provide guidelines for this process. We demonstrate how layouts can be related through animated transitions to reduce the cognitive load associated with their reconfiguration whilst supporting the exploratory process. | false | false | [
"Aidan Slingsby",
"Jason Dykes",
"Jo Wood"
] | [
"HM"
] | [] | [] |
InfoVis | 2,009 | Conjunctive Visual Forms | 10.1109/TVCG.2009.129 | Visual exploration of multidimensional data is a process of isolating and extracting relationships within and between dimensions. Coordinated multiple view approaches are particularly effective for visual exploration because they support precise expression of heterogeneous multidimensional queries using simple interactions. Recent visual analytics research has made significant progress in identifying and understanding patterns of composed views and coordinations that support fast, flexible, and open-ended data exploration. What is missing is formalization of the space of expressible queries in terms of visual representation and interaction. This paper introduces the conjunctive visual form model in which visual exploration consists of interactively-driven sequences of transitions between visual states that correspond to conjunctive normal forms in boolean logic. The model predicts several new and useful ways to extend the space of rapidly expressible queries through addition of simple interactive capabilities to existing compositional patterns. Two recent related visual tools offer a subset of these capabilities, providing a basis for conjecturing about such extensions. | false | false | [
"Chris E. Weaver"
] | [] | [] | [] |
InfoVis | 2,009 | Constructing Overview + Detail Dendrogram-Matrix Views | 10.1109/TVCG.2009.130 | A dendrogram that visualizes a clustering hierarchy is often integrated with a re-orderable matrix for pattern identification. The method is widely used in many research fields including biology, geography, statistics, and data mining. However, most dendrograms do not scale up well, particularly with respect to problems of graphical and cognitive information overload. This research proposes a strategy that links an overview dendrogram and a detail-view dendrogram, each integrated with a re-orderable matrix. The overview displays only a user-controlled, limited number of nodes that represent the ldquoskeletonrdquo of a hierarchy. The detail view displays the sub-tree represented by a selected meta-node in the overview. The research presented here focuses on constructing a concise overview dendrogram and its coordination with a detail view. The proposed method has the following benefits: dramatic alleviation of information overload, enhanced scalability and data abstraction quality on the dendrogram, and the support of data exploration at arbitrary levels of detail. The contribution of the paper includes a new metric to measure the ldquoimportancerdquo of nodes in a dendrogram; the method to construct the concise overview dendrogram from the dynamically-identified, important nodes; and measure for evaluating the data abstraction quality for dendrograms. We evaluate and compare the proposed method to some related existing methods, and demonstrating how the proposed method can help users find interesting patterns through a case study on county-level U.S. cervical cancer mortality and demographic data. | false | false | [
"Jin Chen",
"Alan M. MacEachren",
"Donna Peuquet"
] | [] | [] | [] |
InfoVis | 2,009 | Document Cards: A Top Trumps Visualization for Documents | 10.1109/TVCG.2009.139 | Finding suitable, less space consuming views for a document's main content is crucial to provide convenient access to large document collections on display devices of different size. We present a novel compact visualization which represents the document's key semantic as a mixture of images and important key terms, similar to cards in a top trumps game. The key terms are extracted using an advanced text mining approach based on a fully automatic document structure extraction. The images and their captions are extracted using a graphical heuristic and the captions are used for a semi-semantic image weighting. Furthermore, we use the image color histogram for classification and show at least one representative from each non-empty image class. The approach is demonstrated for the IEEE InfoVis publications of a complete year. The method can easily be applied to other publication collections and sets of documents which contain images. | false | false | [
"Hendrik Strobelt",
"Daniela Oelke",
"Christian Rohrdantz",
"Andreas Stoffel",
"Daniel A. Keim",
"Oliver Deussen"
] | [] | [] | [] |
InfoVis | 2,009 | Exemplar-based Visualization of Large Document Corpus | 10.1109/TVCG.2009.140 | With the rapid growth of the World Wide Web and electronic information services, text corpus is becoming available online at an incredible rate. By displaying text data in a logical layout (e.g., color graphs), text visualization presents a direct way to observe the documents as well as understand the relationship between them. In this paper, we propose a novel technique, Exemplar-based visualization (EV), to visualize an extremely large text corpus. Capitalizing on recent advances in matrix approximation and decomposition, EV presents a probabilistic multidimensional projection model in the low-rank text subspace with a sound objective function. The probability of each document proportion to the topics is obtained through iterative optimization and embedded to a low dimensional space using parameter embedding. By selecting the representative exemplars, we obtain a compact approximation of the data. This makes the visualization highly efficient and flexible. In addition, the selected exemplars neatly summarize the entire data set and greatly reduce the cognitive overload in the visualization, leading to an easier interpretation of large text corpus. Empirically, we demonstrate the superior performance of EV through extensive experiments performed on the publicly available text data sets. | false | false | [
"Yanhua Chen",
"Lijun Wang",
"Ming Dong 0001",
"Jing Hua 0001"
] | [] | [] | [] |
InfoVis | 2,009 | Flow Mapping and Multivariate Visualization of Large Spatial Interaction Data | 10.1109/TVCG.2009.143 | Spatial interactions (or flows), such as population migration and disease spread, naturally form a weighted location-to-location network (graph). Such geographically embedded networks (graphs) are usually very large. For example, the county-to-county migration data in the U.S. has thousands of counties and about a million migration paths. Moreover, many variables are associated with each flow, such as the number of migrants for different age groups, income levels, and occupations. It is a challenging task to visualize such data and discover network structures, multivariate relations, and their geographic patterns simultaneously. This paper addresses these challenges by developing an integrated interactive visualization framework that consists three coupled components: (1) a spatially constrained graph partitioning method that can construct a hierarchy of geographical regions (communities), where there are more flows or connections within regions than across regions; (2) a multivariate clustering and visualization method to detect and present multivariate patterns in the aggregated region-to-region flows; and (3) a highly interactive flow mapping component to map both flow and multivariate patterns in the geographic space, at different hierarchical levels. The proposed approach can process relatively large data sets and effectively discover and visualize major flow structures and multivariate relations at the same time. User interactions are supported to facilitate the understanding of both an overview and detailed patterns. | false | false | [
"Diansheng Guo"
] | [] | [] | [] |
InfoVis | 2,009 | FromDaDy: Spreading Aircraft Trajectories Across Views to Support Iterative Queries | 10.1109/TVCG.2009.145 | When displaying thousands of aircraft trajectories on a screen, the visualization is spoiled by a tangle of trails. The visual analysis is therefore difficult, especially if a specific class of trajectories in an erroneous dataset has to be studied. We designed FromDaDy, a trajectory visualization tool that tackles the difficulties of exploring the visualization of multiple trails. This multidimensional data exploration is based on scatterplots, brushing, pick and drop, juxtaposed views and rapid visual design. Users can organize the workspace composed of multiple juxtaposed views. They can define the visual configuration of the views by connecting data dimensions from the dataset to Bertin's visual variables. They can then brush trajectories, and with a pick and drop operation they can spread the brushed information across views. They can then repeat these interactions, until they extract a set of relevant data, thus formulating complex queries. Through two real-world scenarios, we show how FromDaDy supports iterative queries and the extraction of trajectories in a dataset that contains up to 5 million data. | false | false | [
"Christophe Hurter",
"Benjamin Tissoires",
"Stéphane Conversy"
] | [] | [] | [] |
InfoVis | 2,009 | GeneShelf: A Web-based Visual Interface for Large Gene Expression Time-Series Data Repositories | 10.1109/TVCG.2009.146 | A widespread use of high-throughput gene expression analysis techniques enabled the biomedical research community to share a huge body of gene expression datasets in many public databases on the web. However, current gene expression data repositories provide static representations of the data and support limited interactions. This hinders biologists from effectively exploring shared gene expression datasets. Responding to the growing need for better interfaces to improve the utility of the public datasets, we have designed and developed a new web-based visual interface entitled GeneShelf (http://bioinformatics.cnmcresearch.org/GeneShelf). It builds upon a zoomable grid display to represent two categorical dimensions. It also incorporates an augmented timeline with expandable time points that better shows multiple data values for the focused time point by embedding bar charts. We applied GeneShelf to one of the largest microarray datasets generated to study the progression and recovery process of injuries at the spinal cord of mice and rats. We present a case study and a preliminary qualitative user study with biologists to show the utility and usability of GeneShelf. | false | false | [
"Bo Hyoung Kim",
"Bongshin Lee",
"Susan Knoblach",
"Eric P. Hoffman",
"Jinwook Seo"
] | [] | [] | [] |
InfoVis | 2,009 | Harnessing the Information Ecosystem with Wiki-based Visualization Dashboards | 10.1109/TVCG.2009.148 | We describe the design and deployment of Dashiki, a public Website where users may collaboratively build visualization dashboards through a combination of a wiki-like syntax and interactive editors. Our goals are to extend existing research on social data analysis into presentation and organization of data from multiple sources, explore new metaphors for these activities, and participate more fully in the Web's information ecology by providing tighter integration with real-time data. To support these goals, our design includes novel and low-barrier mechanisms for editing and layout of dashboard pages and visualizations, connection to data sources, and coordinating interaction between visualizations. In addition to describing these technologies, we provide a preliminary report on the public launch of a prototype based on this design, including a description of the activities of our users derived from observation and interviews. | false | false | [
"Matt McKeon"
] | [] | [] | [] |
InfoVis | 2,009 | Interaction Techniques for Selecting and Manipulating Subgraphs in Network Visualizations | 10.1109/TVCG.2009.151 | We present a novel and extensible set of interaction techniques for manipulating visualizations of networks by selecting subgraphs and then applying various commands to modify their layout or graphical properties. Our techniques integrate traditional rectangle and lasso selection, and also support selecting a node's neighbourhood by dragging out its radius (in edges) using a novel kind of radial menu. Commands for translation, rotation, scaling, or modifying graphical properties (such as opacity) and layout patterns can be performed by using a hotbox (a transiently popped-up, semi-transparent set of widgets) that has been extended in novel ways to integrate specification of commands with 1D or 2D arguments. Our techniques require only one mouse button and one keyboard key, and are designed for fast, gestural, in-place interaction. We present the design and integration of these interaction techniques, and illustrate their use in interactive graph visualization. Our techniques are implemented in NAViGaTOR, a software package for visualizing and analyzing biological networks. An initial usability study is also reported. | false | false | [
"Michael J. McGuffin",
"Igor Jurisica"
] | [
"HM"
] | [] | [] |
InfoVis | 2,009 | Interactive Dimensionality Reduction Through User-defined Combinations of Quality Metrics | 10.1109/TVCG.2009.153 | Multivariate data sets including hundreds of variables are increasingly common in many application areas. Most multivariate visualization techniques are unable to display such data effectively, and a common approach is to employ dimensionality reduction prior to visualization. Most existing dimensionality reduction systems focus on preserving one or a few significant structures in data. For many analysis tasks, however, several types of structures can be of high significance and the importance of a certain structure compared to the importance of another is often task-dependent. This paper introduces a system for dimensionality reduction by combining user-defined quality metrics using weight functions to preserve as many important structures as possible. The system aims at effective visualization and exploration of structures within large multivariate data sets and provides enhancement of diverse structures by supplying a range of automatic variable orderings. Furthermore it enables a quality-guided reduction of variables through an interactive display facilitating investigation of trade-offs between loss of structure and the number of variables to keep. The generality and interactivity of the system is demonstrated through a case scenario. | false | false | [
"Sara Johansson 0001",
"Jimmy Johansson 0001"
] | [] | [] | [] |
InfoVis | 2,009 | Lark: Coordinating Co-located Collaboration with Information Visualization | 10.1109/TVCG.2009.162 | Large multi-touch displays are expanding the possibilities of multiple-coordinated views by allowing multiple people to interact with data in concert or independently. We present Lark, a system that facilitates the coordination of interactions with information visualizations on shared digital workspaces. We focus on supporting this coordination according to four main criteria: scoped interaction, temporal flexibility, spatial flexibility, and changing collaboration styles. These are achieved by integrating a representation of the information visualization pipeline into the shared workspace, thus explicitly indicating coordination points on data, representation, presentation, and view levels. This integrated meta-visualization supports both the awareness of how views are linked and the freedom to work in concert or independently. Lark incorporates these four main criteria into a coherent visualization collaboration interaction environment by providing direct visual and algorithmic support for the coordination of data analysis actions over shared large displays. | false | false | [
"Matthew Tobiasz",
"Petra Isenberg",
"Sheelagh Carpendale"
] | [] | [] | [] |
InfoVis | 2,009 | Mapping Text with Phrase Nets | 10.1109/TVCG.2009.165 | We present a new technique, the phrase net, for generating visual overviews of unstructured text. A phrase net displays a graph whose nodes are words and whose edges indicate that two words are linked by a user-specified relation. These relations may be defined either at the syntactic or lexical level; different relations often produce very different perspectives on the same text. Taken together, these perspectives often provide an illuminating visual overview of the key concepts and relations in a document or set of documents. | false | false | [
"Frank van Ham",
"Martin Wattenberg",
"Fernanda B. Viégas"
] | [
"BP"
] | [] | [] |
InfoVis | 2,009 | MizBee: A Multiscale Synteny Browser | 10.1109/TVCG.2009.167 | In the field of comparative genomics, scientists seek to answer questions about evolution and genomic function by comparing the genomes of species to find regions of shared sequences. Conserve dsyntenic blocks are an important biological data abstraction for indicating regions of shared sequences. The goal of this work is to show multiple types of relationships at multiple scales in a way that is visually comprehensible in accordance with known perceptual principles. We present a task analysis for this domain where the fundamental questions asked by biologists can be understood by a characterization of relationships into the four types of proximity/location, size, orientation, and similarity/strength, and the four scales of genome, chromosome, block, and genomic feature. We also propose a new taxonomy of the design space for visually encoding conservation data. We present MizBee, a multiscale synteny browser with the unique property of providing interactive side-by-side views of the data across the range of scales supporting exploration of all of these relationship types. We conclude with case studies from two biologists who used MizBee to augment their previous automatic analysis work flow, providing anecdotal evidence about the efficacy of the system for the visualization of syntenic data, the analysis of conservation relationships, and the communication of scientific insights. | false | false | [
"Miriah D. Meyer",
"Tamara Munzner",
"Hanspeter Pfister"
] | [
"HM"
] | [] | [] |
InfoVis | 2,009 | Participatory Visualization with Wordle | 10.1109/TVCG.2009.171 | We discuss the design and usage of ldquoWordle,rdquo a Web-based tool for visualizing text. Wordle creates tag-cloud-like displays that give careful attention to typography, color, and composition. We describe the algorithms used to balance various aesthetic criteria and create the distinctive Wordle layouts. We then present the results of a study of Wordle usage, based both on spontaneous behaviour observed in the wild, and on a large-scale survey of Wordle users. The results suggest that Wordles have become a kind of medium of expression, and that a ldquoparticipatory culturerdquo has arisen around them. | false | false | [
"Fernanda B. Viégas",
"Martin Wattenberg",
"Jonathan Feinberg"
] | [] | [] | [] |
InfoVis | 2,009 | Protovis: A Graphical Toolkit for Visualization | 10.1109/TVCG.2009.174 | Despite myriad tools for visualizing data, there remains a gap between the notational efficiency of high-level visualization systems and the expressiveness and accessibility of low-level graphical systems. Powerful visualization systems may be inflexible or impose abstractions foreign to visual thinking, while graphical systems such as rendering APIs and vector-based drawing programs are tedious for complex work. We argue that an easy-to-use graphical system tailored for visualization is needed. In response, we contribute Protovis, an extensible toolkit for constructing visualizations by composing simple graphical primitives. In Protovis, designers specify visualizations as a hierarchy of marks with visual properties defined as functions of data. This representation achieves a level of expressiveness comparable to low-level graphics systems, while improving efficiency - the effort required to specify a visualization - and accessibility - the effort required to learn and modify the representation. We substantiate this claim through a diverse collection of examples and comparative analysis with popular visualization tools. | false | false | [
"Michael Bostock",
"Jeffrey Heer"
] | [] | [] | [] |
InfoVis | 2,009 | ResultMaps: Visualization for Search Interfaces | 10.1109/TVCG.2009.176 | Hierarchical representations are common in digital repositories, yet are not always fully leveraged in their online search interfaces. This work describes ResultMaps, which use hierarchical treemap representations with query string-driven digital library search engines. We describe two lab experiments, which find that ResultsMap users yield significantly better results over a control condition on some subjective measures, and we find evidence that ResultMaps have ancillary benefits via increased understanding of some aspects of repository content. The ResultMap system and experiments contribute an understanding of the benefits-direct and indirect-of the ResultMap approach to repository search visualization. | false | false | [
"Edward Clarkson",
"Krishna Desai",
"James D. Foley"
] | [] | [] | [] |
InfoVis | 2,009 | Scattering Points in Parallel Coordinates | 10.1109/TVCG.2009.179 | In this paper, we present a novel parallel coordinates design integrated with points (scattering points in parallel coordinates, SPPC), by taking advantage of both parallel coordinates and scatterplots. Different from most multiple views visualization frameworks involving parallel coordinates where each visualization type occupies an individual window, we convert two selected neighboring coordinate axes into a scatterplot directly. Multidimensional scaling is adopted to allow converting multiple axes into a single subplot. The transition between two visual types is designed in a seamless way. In our work, a series of interaction tools has been developed. Uniform brushing functionality is implemented to allow the user to perform data selection on both points and parallel coordinate polylines without explicitly switching tools. A GPU accelerated dimensional incremental multidimensional scaling (DIMDS) has been developed to significantly improve the system performance. Our case study shows that our scheme is more efficient than traditional multi-view methods in performing visual analysis tasks. | false | false | [
"Xiaoru Yuan",
"Peihong Guo",
"He Xiao",
"Hong Zhou 0004",
"Huamin Qu"
] | [] | [] | [] |
InfoVis | 2,009 | SellTrend: Inter-Attribute Visual Analysis of Temporal Transaction Data | 10.1109/TVCG.2009.180 | We present a case study of our experience designing SellTrend, a visualization system for analyzing airline travel purchase requests. The relevant transaction data can be characterized as multi-variate temporal and categorical event sequences, and the chief problem addressed is how to help company analysts identify complex combinations of transaction attributes that contribute to failed purchase requests. SellTrend combines a diverse set of techniques ranging from time series visualization to faceted browsing and historical trend analysis in order to help analysts make sense of the data. We believe that the combination of views and interaction capabilities in SellTrend provides an innovative approach to this problem and to other similar types of multivariate, temporally driven transaction data analysis. Initial feedback from company analysts confirms the utility and benefits of the system. | false | false | [
"Zhicheng Liu",
"John T. Stasko",
"Timothy Sullivan"
] | [
"HM"
] | [] | [] |
InfoVis | 2,009 | Smooth Graphs for Visual Exploration of Higher-Order State Transitions | 10.1109/TVCG.2009.181 | In this paper, we present a new visual way of exploring state sequences in large observational time-series. A key advantage of our method is that it can directly visualize higher-order state transitions. A standard first order state transition is a sequence of two states that are linked by a transition. A higher-order state transition is a sequence of three or more states where the sequence of participating states are linked together by consecutive first order state transitions. Our method extends the current state-graph exploration methods by employing a two dimensional graph, in which higher-order state transitions are visualized as curved lines. All transitions are bundled into thick splines, so that the thickness of an edge represents the frequency of instances. The bundling between two states takes into account the state transitions before and after the transition. This is done in such a way that it forms a continuous representation in which any subsequence of the timeseries is represented by a continuous smooth line. The edge bundles in these graphs can be explored interactively through our incremental selection algorithm. We demonstrate our method with an application in exploring labeled time-series data from a biological survey, where a clustering has assigned a single label to the data at each time-point. In these sequences, a large number of cyclic patterns occur, which in turn are linked to specific activities. We demonstrate how our method helps to find these cycles, and how the interactive selection process helps to find and investigate activities. | false | false | [
"Jorik Blaas",
"Charl P. Botha",
"Edward Grundy",
"Mark W. Jones",
"Robert S. Laramee",
"Frits H. Post"
] | [] | [] | [] |
InfoVis | 2,009 | Spatiotemporal Analysis of Sensor Logs using Growth Ring Maps | 10.1109/TVCG.2009.182 | Spatiotemporal analysis of sensor logs is a challenging research field due to three facts: a) traditional two-dimensional maps do not support multiple events to occur at the same spatial location, b) three-dimensional solutions introduce ambiguity and are hard to navigate, and c) map distortions to solve the overlap problem are unfamiliar to most users. This paper introduces a novel approach to represent spatial data changing over time by plotting a number of non-overlapping pixels, close to the sensor positions in a map. Thereby, we encode the amount of time that a subject spent at a particular sensor to the number of plotted pixels. Color is used in a twofold manner; while distinct colors distinguish between sensor nodes in different regions, the colors' intensity is used as an indicator to the temporal property of the subjects' activity. The resulting visualization technique, called growth ring maps, enables users to find similarities and extract patterns of interest in spatiotemporal data by using humans' perceptual abilities. We demonstrate the newly introduced technique on a dataset that shows the behavior of healthy and Alzheimer transgenic, male and female mice. We motivate the new technique by showing that the temporal analysis based on hierarchical clustering and the spatial analysis based on transition matrices only reveal limited results. Results and findings are cross-validated using multidimensional scaling. While the focus of this paper is to apply our visualization for monitoring animal behavior, the technique is also applicable for analyzing data, such as packet tracing, geographic monitoring of sales development, or mobile phone capacity planning. | false | false | [
"Peter Bak",
"Florian Mansmann",
"Halldór Janetzko",
"Daniel A. Keim"
] | [] | [] | [] |
InfoVis | 2,009 | SpicyNodes: Radial Layout Authoring for the General Public | 10.1109/TVCG.2009.183 | Trees and graphs are relevant to many online tasks such as visualizing social networks, product catalogs, educational portals, digital libraries, the semantic web, concept maps and personalized information management. SpicyNodes is an information-visualization technology that builds upon existing research on radial tree layouts and graph structures. Users can browse a tree, clicking from node to node, as well as successively viewing a node, immediately related nodes and the path back to the ldquohomerdquo nodes. SpicyNodes' layout algorithms maintain balanced layouts using a hybrid mixture of a geometric layout (a succession of spanning radial trees) and force-directed layouts to minimize overlapping nodes, plus several other improvements over prior art. It provides XML-based API and GUI authoring tools. The goal of the SpicyNodes project is to implement familiar principles of radial maps and focus+context with an attractive and inviting look and feel in an open system that is accessible to virtually any Internet user. | false | false | [
"Michael Douma",
"Grzegorz Ligierko",
"Ovidiu Ancuta",
"Pavel Gritsai",
"Sean Liu"
] | [] | [] | [] |
InfoVis | 2,009 | Temporal Summaries: Supporting Temporal Categorical Searching, Aggregation and Comparison | 10.1109/TVCG.2009.187 | When analyzing thousands of event histories, analysts often want to see the events as an aggregate to detect insights and generate new hypotheses about the data. An analysis tool must emphasize both the prevalence and the temporal ordering of these events. Additionally, the analysis tool must also support flexible comparisons to allow analysts to gather visual evidence. In a previous work, we introduced align, rank, and filter (ARF) to accentuate temporal ordering. In this paper, we present temporal summaries, an interactive visualization technique that highlights the prevalence of event occurrences. Temporal summaries dynamically aggregate events in multiple granularities (year, month, week, day, hour, etc.) for the purpose of spotting trends over time and comparing several groups of records. They provide affordances for analysts to perform temporal range filters. We demonstrate the applicability of this approach in two extensive case studies with analysts who applied temporal summaries to search, filter, and look for patterns in electronic health records and academic records. | false | false | [
"Taowei David Wang",
"Catherine Plaisant",
"Ben Shneiderman",
"Neil Spring",
"David Roseman",
"Greg Marchand",
"Vikramjit Mukherjee",
"Mark S. Smith"
] | [] | [] | [] |
InfoVis | 2,009 | The Benefits of Synchronous Collaborative Information Visualization: Evidence from an Experimental Evaluation | 10.1109/TVCG.2009.188 | A great corpus of studies reports empirical evidence of how information visualization supports comprehension and analysis of data. The benefits of visualization for synchronous group knowledge work, however, have not been addressed extensively. Anecdotal evidence and use cases illustrate the benefits of synchronous collaborative information visualization, but very few empirical studies have rigorously examined the impact of visualization on group knowledge work. We have consequently designed and conducted an experiment in which we have analyzed the impact of visualization on knowledge sharing in situated work groups. Our experimental study consists of evaluating the performance of 131 subjects (all experienced managers) in groups of 5 (for a total of 26 groups), working together on a real-life knowledge sharing task. We compare (1) the control condition (no visualization provided), with two visualization supports: (2) optimal and (3) suboptimal visualization (based on a previous survey). The facilitator of each group was asked to populate the provided interactive visual template with insights from the group, and to organize the contributions according to the group consensus. We have evaluated the results through both objective and subjective measures. Our statistical analysis clearly shows that interactive visualization has a statistically significant, objective and positive impact on the outcomes of knowledge sharing, but that the subjects seem not to be aware of this. In particular, groups supported by visualization achieved higher productivity, higher quality of outcome and greater knowledge gains. No statistically significant results could be found between an optimal and a suboptimal visualization though (as classified by the pre-experiment survey). Subjects also did not seem to be aware of the benefits that the visualizations provided as no difference between the visualization and the control conditions was found for the self-reported measures of satisfaction and participation. An implication of our study for information visualization applications is to extend them by using real-time group annotation functionalities that aid in the group sense making process of the represented data. | false | false | [
"Sabrina Bresciani",
"Martin J. Eppler"
] | [] | [] | [] |
InfoVis | 2,009 | Towards Utilizing GPUs in Information Visualization: A Model and Implementation of Image-Space Operations | 10.1109/TVCG.2009.191 | Modern programmable GPUs represent a vast potential in terms of performance and visual flexibility for information visualization research, but surprisingly few applications even begin to utilize this potential. In this paper, we conjecture that this may be due to the mismatch between the high-level abstract data types commonly visualized in our field, and the low-level floating-point model supported by current GPU shader languages. To help remedy this situation, we present a refinement of the traditional information visualization pipeline that is amenable to implementation using GPU shaders. The refinement consists of a final image-space step in the pipeline where the multivariate data of the visualization is sampled in the resolution of the current view. To concretize the theoretical aspects of this work, we also present a visual programming environment for constructing visualization shaders using a simple drag-and-drop interface. Finally, we give some examples of the use of shaders for well-known visualization techniques. | false | false | [
"Bryan McDonnel",
"Niklas Elmqvist"
] | [] | [] | [] |
InfoVis | 2,009 | Visual Analysis of Inter-Process Communication for Large-Scale Parallel Computing | 10.1109/TVCG.2009.196 | In serial computation, program profiling is often helpful for optimization of key sections of code. When moving to parallel computation, not only does the code execution need to be considered but also communication between the different processes which can induce delays that are detrimental to performance. As the number of processes increases, so does the impact of the communication delays on performance. For large-scale parallel applications, it is critical to understand how the communication impacts performance in order to make the code more efficient. There are several tools available for visualizing program execution and communications on parallel systems. These tools generally provide either views which statistically summarize the entire program execution or process-centric views. However, process-centric visualizations do not scale well as the number of processes gets very large. In particular, the most common representation of parallel processes is a Gantt chart with a row for each process. As the number of processes increases, these charts can become difficult to work with and can even exceed screen resolution. We propose a new visualization approach that affords more scalability and then demonstrate it on systems running with up to 16,384 processes. | false | false | [
"Chris Muelder",
"François Gygi",
"Kwan-Liu Ma"
] | [] | [] | [] |
InfoVis | 2,009 | Visualizing Social Photos on a Hasse Diagram for Eliciting Relations and Indexing New Photos | 10.1109/TVCG.2009.201 | Social photos, which are taken during family events or parties, represent individuals or groups of people. We show in this paper how a Hasse diagram is an efficient visualization strategy for eliciting different groups and navigating through them. However, we do not limit this strategy to these traditional uses. Instead we show how it can also be used for assisting in indexing new photos. Indexing consists of identifying the event and people in photos. It is an integral phase that takes place before searching and sharing. In our method we use existing indexed photos to index new photos. This is performed through a manual drag and drop procedure followed by a content fusion process that we call 'propagation'. At the core of this process is the necessity to organize and visualize the photos that will be used for indexing in a manner that is easily recognizable and accessible by the user. In this respect we make use of an object Galois sub-hierarchy and display it using a Hasse diagram. The need for an incremental display that maintains the user's mental map also leads us to propose a novel way of building the Hasse diagram. To validate the approach, we present some tests conducted with a sample of users that confirm the interest of this organization, visualization and indexation approach. Finally, we conclude by considering scalability, the possibility to extract social networks and automatically create personalised albums. | false | false | [
"Michel Crampes",
"Jeremy de Oliveira-Kumar",
"Sylvie Ranwez",
"Jean Villerd"
] | [] | [] | [] |
InfoVis | 2,009 | Visualizing the Intellectual Structure with Paper-Reference Matrices | 10.1109/TVCG.2009.202 | Visualizing the intellectual structure of scientific domains using co-cited units such as references or authors has become a routine for domain analysis. In previous studies, paper-reference matrices are usually transformed into reference-reference matrices to obtain co-citation relationships, which are then visualized in different representations, typically as node-link networks, to represent the intellectual structures of scientific domains. Such network visualizations sometimes contain tightly knit components, which make visual analysis of the intellectual structure a challenging task. In this study, we propose a new approach to reveal co-citation relationships. Instead of using a reference-reference matrix, we directly use the original paper-reference matrix as the information source, and transform the paper-reference matrix into an FP-tree and visualize it in a Java-based prototype system. We demonstrate the usefulness of our approach through visual analyses of the intellectual structure of two domains: information visualization and Sloan Digital Sky Survey (SDSS). The results show that our visualization not only retains the major information of co-citation relationships, but also reveals more detailed sub-structures of tightly knit clusters than a conventional node-link network visualization. | false | false | [
"Jian Zhang 0006",
"Chaomei Chen",
"Jiexun Li"
] | [] | [] | [] |
EuroVis | 2,009 | A Directional Occlusion Shading Model for Interactive Direct Volume Rendering | 10.1111/j.1467-8659.2009.01464.x | Volumetric rendering is widely used to examine 3D scalar fields from CT/MRI scanners and numerical simulation datasets. One key aspect of volumetric rendering is the ability to provide perceptual cues to aid in understanding structure contained in the data. While shading models that reproduce natural lighting conditions have been shown to better convey depth information and spatial relationships, they traditionally require considerable (pre)computation. In this paper, a shading model for interactive direct volume rendering is proposed that provides perceptual cues similar to those of ambient occlusion, for both solid and transparent surface‐like features. An image space occlusion factor is derived from the radiative transport equation based on a specialized phase function. The method does not rely on any precomputation and thus allows for interactive explorations of volumetric data sets via on‐the‐fly editing of the shading model parameters or (multi‐dimensional) transfer functions while modifications to the volume via clipping planes are incorporated into the resulting occlusion‐based shading. | false | false | [
"Mathias Schott",
"Vincent Pegoraro",
"Charles D. Hansen",
"Kevin Boulanger",
"Kadi Bouatouch"
] | [] | [] | [] |
EuroVis | 2,009 | A Visualization Based Approach for Digital Signature Authentication | 10.1111/j.1467-8659.2009.01455.x | We propose a visualization based approach for digital signature authentication. Using our method, the speed and pressure aspects of a digital signature process can be clearly and intuitively conveyed to the user for digital signature authentication. Our design takes into account both the expressiveness and aesthetics of the derived visual patterns. With the visual aid provided by our method, digital signatures can be authenticated with better accuracy than using existing methods—even novices can examine the authenticity of a digital signature in most situations using our method. To validate the effectiveness of our method, we conducted a comprehensive user study which confirms positively the advantages of our approach. Our method can be employed as a new security enhancement measure for a range of business and legal applications in reality which involve digital signature authorization and authentication. | false | false | [
"Songhua Xu",
"Wenxia Yang",
"Francis C. M. Lau 0001"
] | [] | [] | [] |
EuroVis | 2,009 | Accelerating Volume Raycasting using Proxy Spheres | 10.1111/j.1467-8659.2009.01466.x | In this paper, we propose an efficient solution that addresses the performance problems of current single‐pass GPU raycasting algorithms. Our paper provides more control over the rendering process by introducing tighter ray segments for raycasting, while at the same time avoiding the introduction of any new rendering artefacts. We achieve this by dynamically generating, on the GPU, a coarsely fitted proxy geometry, composed of spheres, for the active blocks. The spheres are then rasterised into two z‐buffers by a single rendering pass. The resulting two z‐buffers are used as the first‐hit and last‐hit points for the subsequent raycaster. With this approach, only the valid ray segments between the two z‐buffers need to be sampled during raycasting. This also provides more coherent parallelism on the GPU due to more consistent ray length and avoidance of the overheads and dynamic branching of performing checks on a per‐sample basis during the raycasting pass.Our technique is ideal for dynamic data exploration in which both the transfer function and view parameters need to be changed frequently at runtime. The rendering results of our algorithm are identical to the general cube‐based proxy geometry algorithm, but the performance can be up to 15.7 times faster. Furthermore, the approach can be adopted by any existing raycasting system in a straightforward way. | false | false | [
"Baoquan Liu",
"Gordon Clapworthy",
"Feng Dong 0005"
] | [] | [] | [] |
EuroVis | 2,009 | Bivariate Transfer Functions on Unstructured Grids | 10.1111/j.1467-8659.2009.01473.x | Multi‐dimensional transfer functions are commonly used in rectilinear volume renderings to effectively portray materials, material boundaries and even subtle variations along boundaries. However, most unstructured grid rendering algorithms only employ one‐dimensional transfer functions. This paper proposes a novel pre‐integrated Projected Tetrahedra (PT) rendering technique that applies bivariate transfer functions on unstructured grids. For each type of bivariate transfer function, an analytical form that pre‐integrates the contribution of a ray segment in one tetrahedron is derived, and can be precomputed as a lookup table to compute the color and opacity in a projected tetrahedron on‐the‐fly. Further, we show how to approximate the integral using the pre‐integration method for faster unstructured grid rendering. We demonstrate the advantages of our approach with a variety of examples and comparisons with one‐dimensional transfer functions. | false | false | [
"Yuyan Song",
"Wei Chen 0001",
"Ross Maciejewski",
"Kelly P. Gaither",
"David S. Ebert"
] | [] | [] | [] |
EuroVis | 2,009 | Collaborative Brushing and Linking for Co-located Visual Analytics of Document Collections | 10.1111/j.1467-8659.2009.01444.x | Many real‐world analysis tasks can benefit from the combined efforts of a group of people. Past research has shown that to design visualizations for collaborative visual analytics tasks, we need to support both individual as well as joint analysis activities. We present Cambiera, a tabletop visual analytics tool that supports individual and collaborative information foraging activities in large text document collections. We define collaborative brushing and linking as an awareness mechanism that enables analysts to follow their own hypotheses during collaborative sessions while still remaining aware of the group's activities. With Cambiera, users are able to collaboratively search through documents, maintaining awareness of each others' work and building on each others' findings. | false | false | [
"Petra Isenberg",
"Danyel Fisher"
] | [
"HM"
] | [] | [] |
EuroVis | 2,009 | Comparing Parameter Manipulation with Mouse, Pen, and Slider User Interfaces | 10.1111/j.1467-8659.2009.01457.x | Visual fixation on one's tool(s) takes much attention away from one's primary task. Following the belief that the best tools ‘disappear’ and become invisible to the user, we present a study comparing visual fixations (eye gaze within locations on a graphical display) and performance for mouse, pen, and physical slider user interfaces. Participants conducted a controlled, yet representative, color matching task that required user interaction representative of many data exploration tasks such as parameter exploration of medical or fuel cell data. We demonstrate that users may spend up to 95% fewer visual fixations on physical sliders versus standard mouse and pen tools without any loss in performance for a generalized visual performance task. | false | false | [
"Colin Swindells",
"Melanie Tory",
"Rebecca Dreezer"
] | [] | [] | [] |
EuroVis | 2,009 | Context-aware Volume Modeling of Skeletal Muscles | 10.1111/j.1467-8659.2009.01460.x | This paper presents an interactive volume modeling method that constructs skeletal muscles from an existing volumetric dataset. Our approach provides users with an intuitive modeling interface and produces compelling results that conform to the characteristic anatomy in the input volume. The algorithmic core of our method is an intuitive anatomy classification approach, suited to accommodate spatial constraints on the muscle volume. The presented work is useful in illustrative visualization, volumetric information fusion and volume illustration that involve muscle modeling, where the spatial context should be faithfully preserved. | false | false | [
"Zhicheng Yan",
"Wei Chen 0001",
"Aidong Lu",
"David S. Ebert"
] | [] | [] | [] |
EuroVis | 2,009 | Direct Visualization of Deformation in Volumes | 10.1111/j.1467-8659.2009.01471.x | Deformation is a topic of interest in many disciplines. In particular in medical research, deformations of surfaces and even entire volumetric structures are of interest. Clear visualization of such deformations can lead to important insight into growth processes and progression of disease.We present new techniques for direct focus+context visualization of deformation fields representing transformations between pairs of volumetric datasets. Typically, such fields are computed by performing a non‐rigid registration between two data volumes. Our visualization is based on direct volume rendering and uses the GPU to compute and interactively visualize features of these deformation fields in real‐time. We integrate visualization of the deformation field with visualization of the scalar volume affected by the deformations. Furthermore, we present a novel use of texturing in volume rendered visualizations to show additional properties of the vector field on surfaces in the volume. | false | false | [
"Stef Busking",
"Charl P. Botha",
"Frits H. Post"
] | [] | [] | [] |
EuroVis | 2,009 | DocuBurst: Visualizing Document Content using Language Structure | 10.1111/j.1467-8659.2009.01439.x | Textual data is at the forefront of information management problems today. One response has been the development of visualizations of text data. These visualizations, commonly based on simple attributes such as relative word frequency, have become increasingly popular tools. We extend this direction, presenting the first visualization of document content which combines word frequency with the human‐created structure in lexical databases to create a visualization that also reflects semantic content. DocuBurst is a radial, space‐filling layout of hyponymy (the IS‐A relation), overlaid with occurrence counts of words in a document of interest to provide visual summaries at varying levels of granularity. Interactive document analysis is supported with geometric and semantic zoom, selectable focus on individual words, and linked access to source text. | false | false | [
"Christopher Collins 0001",
"Sheelagh Carpendale",
"Gerald Penn"
] | [] | [] | [] |
EuroVis | 2,009 | Efficient and Adaptive Rendering of 2-D Continuous Scatterplots | 10.1111/j.1467-8659.2009.01478.x | We extend the rendering technique for continuous scatterplots to allow for a broad class of interpolation methods within the spatial grid instead of only linear interpolation. To do this, we propose an approach that projects the image of a cell from the spatial domain to the scatterplot domain. We approximate this image using either the convex hull or an axis‐aligned rectangle that forms a tight fit of the projected points. In both cases, the approach relies on subdivision in the spatial domain to control the approximation error introduced in the scatterplot domain. Acceleration of this algorithm in homogeneous regions of the spatial domain is achieved using an octree hierarchy. The algorithm is scalable and adaptive since it allows us to balance computation time and scatterplot quality. We evaluate and discuss the results with respect to accuracy and computational speed. Our methods are applied to examples of 2‐D transfer function design. | false | false | [
"Sven Bachthaler",
"Daniel Weiskopf"
] | [] | [] | [] |
EuroVis | 2,009 | Enclosing Surfaces for Point Clusters Using 3D Discrete Voronoi Diagrams | 10.1111/j.1467-8659.2009.01448.x | Point clusters occur in both spatial and non‐spatial data. In the former context they may represent segmented particle data, in the latter context they may represent clusters in scatterplots. In order to visualize such point clusters, enclosing surfaces lead to much better comprehension than pure point renderings.We propose a flexible system for the generation of enclosing surfaces for 3D point clusters. We developed a GPU‐based 3D discrete Voronoi diagram computation that supports all surface extractions. Our system provides three different types of enclosing surfaces. By generating a discrete distance field to the point cluster and extracting an isosurface from the field, an enclosing surface with any distance to the point cluster can be generated. As a second type of enclosing surfaces, a hull of the point cluster is extracted. The generation of the hull uses a projection of the discrete Voronoi diagram of the point cluster to an isosurface to generate a polygonal surface. Generated hulls of non‐convex clusters are also non‐convex. The third type of enclosing surfaces can be created by computing a distance field to the hull and extracting an isosurface from the distance field. This method exhibits reduced bumpiness and can extract surfaces arbitrarily close to the point cluster without losing connectedness.We apply our methods to the visualization of multidimensional spatial and non‐spatial data. Multidimensional clusters are extracted and projected into a 3D visual space, where the point clusters are visualized. The respective clusters can also be visualized in object space when dealing with multidimensional particle data. | false | false | [
"Paul Rosenthal",
"Lars Linsen"
] | [] | [] | [] |
EuroVis | 2,009 | Extended Excentric Labeling | 10.1111/j.1467-8659.2009.01456.x | The paper presents an extension to the Excentric Labeling, a labeling technique to dynamically show labels around a movable lens. Each labels refers to one object within the lens and is connected to it through a line. The original implementation has several known limitations and potential improvements that we address in this work, like: high density areas, uneven density distributions, and summary statistics. We describe the implemented extensions and present a think‐aloud user study. The study shows that users can naturally understand and easily operate the majority of the implemented function but label scrolling, which requires additional research. From the study we also gained unanticipated requirements and interesting directions for further research. | false | false | [
"Enrico Bertini",
"Maurizio Rigamonti",
"Denis Lalanne"
] | [] | [] | [] |
EuroVis | 2,009 | Force-Directed Edge Bundling for Graph Visualization | 10.1111/j.1467-8659.2009.01450.x | Graphs depicted as node‐link diagrams are widely used to show relationships between entities. However, node‐link diagrams comprised of a large number of nodes and edges often suffer from visual clutter. The use of edge bundling remedies this and reveals high‐level edge patterns. Previous methods require the graph to contain a hierarchy for this, or they construct a control mesh to guide the edge bundling process, which often results in bundles that show considerable variation in curvature along the overall bundle direction. We present a new edge bundling method that uses a self‐organizing approach to bundling in which edges are modeled as flexible springs that can attract each other. In contrast to previous methods, no hierarchy is used and no control mesh. The resulting bundled graphs show significant clutter reduction and clearly visible high‐level edge patterns. Curvature variation is furthermore minimized, resulting in smooth bundles that are easy to follow. Finally, we present a rendering technique that can be used to emphasize the bundling. | false | false | [
"Danny Holten",
"Jarke J. van Wijk"
] | [] | [] | [] |
EuroVis | 2,009 | Fully Automatic Visualisation of Overlapping Sets | 10.1111/j.1467-8659.2009.01452.x | Visualisation of taxonomies and sets has recently become an active area of research. Many application fields now require more than a strict classification of elements into a hierarchy tree. Euler diagrams, one of the most natural ways of depicting intersecting sets, may provide a solution to these problems.In this paper, we present an approach for the automatic generation of Euler‐like diagrams. This algorithm differs from previous approaches in that it has no undrawable instances of input, allowing it to be used in systems where the output is always required. We also improve the readability of Euler diagrams through the use of Bézier curves and transparent coloured textures. Our approach has been implemented using the Tulip platform. Both the source and executable program used to generate the results are freely available. | false | false | [
"Paolo Simonetto",
"David Auber",
"Daniel Archambault"
] | [] | [] | [] |
EuroVis | 2,009 | Fused Multi-Volume DVR using Binary Space Partitioning | 10.1111/j.1467-8659.2009.01465.x | Multiple‐volume visualization is a growing field in medical imaging providing simultaneous exploration of volumes acquired from varying modalities. However, high complexity results in an increased strain on performance compared to single volume rendering as scenes may consist of volumes with arbitrary orientations and rendering is performed with varying sample densities. Expensive image order techniques such as depth peeling have previously been used to perform the necessary calculations. In this work we present a view‐independent region based scene description for multi‐volume pipelines. Using Binary Space Partitioning we are able to create a simple interface providing all required information for advanced multi‐volume renderings while introducing a minimal overhead for scenes with few volumes. The modularity of our solution is demonstrated by the use of visual development and performance is documented with benchmarks and real‐time simulations. | false | false | [
"Stefan Lindholm",
"Patric Ljung",
"Markus Hadwiger",
"Anders Ynnerman"
] | [] | [] | [] |
EuroVis | 2,009 | Hierarchical Vortex Regions in Swirling Flow | 10.1111/j.1467-8659.2009.01463.x | We propose a new criterion to characterize hierarchical two‐dimensional vortex regions induced by swirling motion. Central to the definition are closed loops that intersect the flow field at a constant angle. The union of loops belonging to the same area of swirling motion defines a vortex region. These regions are disjunct but may be nested, thus introducing a spatial hierarchy of vortex regions. We present a parameter free algorithm for the identification of these regions. Since they are not restricted to star‐ or convex‐shaped geometries, we are able to identify also intricate regions, e.g., of elongated vortices. Computing an integrated value for each loop and mapping these values to a vortex region, introduces new ways for visualizing or filtering the vortex regions. Exemplary, an application based on the Rankine vortex model is presented. We apply our method to several CFD datasets and compare our results to existing approaches. | false | false | [
"Christoph Petz",
"Jens Kasten",
"Steffen Prohaska",
"Hans-Christian Hege"
] | [] | [] | [] |
EuroVis | 2,009 | High-Quality Volumetric Reconstruction on Optimal Lattices for Computed Tomography | 10.1111/j.1467-8659.2009.01445.x | Within the context of emission tomography, we study volumetric reconstruction methods based on the Expectation Maximization (EM) algorithm. We show, for the first time, the equivalence of the standard implementation of the EM‐based reconstruction with an implementation based on hardware‐accelerated volume rendering for nearest‐neighbor (NN) interpolation. This equivalence suggests that higher‐order kernels should be used with caution and do not necessarily lead to better performance. We also show that the EM algorithm can easily be adapted for different lattices, the body‐centered cubic (BCC) one in particular. For validation purposes, we use the 3D version of the Shepp‐Logan synthetic phantom, for which we derive closed‐form analytical expressions of the projection data. The experimental results show the theoretically‐predicted optimality of NN interpolation in combination with the EM algorithm, for both the noiseless and the noisy case. Moreover, reconstruction on the BCC lattice leads to superior accuracy, more compact data representation, and better noise reduction compared to the Cartesian one. Finally, we show the usefulness of the proposed method for optical projection tomography of a mouse embryo. | false | false | [
"Bernhard Finkbeiner",
"Usman R. Alim",
"Dimitri Van De Ville",
"Torsten Möller"
] | [] | [] | [] |
EuroVis | 2,009 | Illuminated 3D Scatterplots | 10.1111/j.1467-8659.2009.01477.x | In contrast to 2D scatterplots, the existing 3D variants have the advantage of showing one additional data dimension, but suffer from inadequate spatial and shape perception and therefore are not well suited to display structures of the underlying data. We improve shape perception by applying a new illumination technique to the pointcloud representation of 3D scatterplots. Points are classified as locally linear, planar, and volumetric structures—according to the eigenvalues of the inverse distance‐weighted covariance matrix at each data element. Based on this classification, different lighting models are applied: codimension‐2 illumination, surface illumination, and emissive volumetric illumination. Our technique lends itself to efficient GPU point rendering and can be combined with existing methods like semi‐transparent rendering, halos, and depth or attribute based color coding. The user can interactively navigate in the dataset and manipulate the classification and other visualization parameters. We demonstrate our visualization technique by showing examples of multi‐dimensional data and of generic pointcloud data. | false | false | [
"Harald Sanftmann",
"Daniel Weiskopf"
] | [] | [] | [] |
EuroVis | 2,009 | Instant Volume Visualization using Maximum Intensity Difference Accumulation | 10.1111/j.1467-8659.2009.01474.x | It has long been recognized that transfer function setup for Direct Volume Rendering (DVR) is crucial to its usability. However, the task of finding an appropriate transfer function is complex and time‐consuming even for experts. Thus, in many practical applications simpler techniques which do not rely on complex transfer functions are employed. One common example is Maximum Intensity Projection (MIP) which depicts the maximum value along each viewing ray. In this paper, we introduce Maximum Intensity Difference Accumulation (MIDA), a new approach which combines the advantages of DVR and MIP. Like MIP, MIDA exploits common data characteristics and hence does not require complex transfer functions to generate good visualization results. It does, however, feature occlusion and shape cues similar to DVR. Furthermore, we show that MIDA – in addition to being a useful technique in its own right – can be used to smoothly transition between DVR and MIP in an intuitive manner. MIDA can be easily implemented using volume raycasting and achieves real‐time performance on current graphics hardware. | false | false | [
"Stefan Bruckner",
"M. Eduard Gröller"
] | [] | [] | [] |
EuroVis | 2,009 | Interactive Visualization of Function Fields by Range-Space Segmentation | 10.1111/j.1467-8659.2009.01480.x | We present a dimension reduction and feature extraction method for the visualization and analysis of function field data. Function fields are a class of high‐dimensional, multi‐variate data in which data samples are one‐dimensional scalar functions. Our approach focuses upon the creation of high‐dimensional range‐space segmentations, from which we can generate meaningful visualizations and extract separating surfaces between features. We demonstrate our approach on high‐dimensional spectral imagery, and particulate pollution data from air quality simulations. | false | false | [
"John C. Anderson",
"Luke J. Gosink",
"Mark A. Duchaineau",
"Kenneth I. Joy"
] | [] | [] | [] |
EuroVis | 2,009 | iPCA: An Interactive System for PCA-based Visual Analytics | 10.1111/j.1467-8659.2009.01475.x | Principle Component Analysis (PCA) is a widely used mathematical technique in many fields for factor and trend analysis, dimension reduction, etc. However, it is often considered to be a “black box” operation whose results are difficult to interpret and sometimes counter‐intuitive to the user. In order to assist the user in better understanding and utilizing PCA, we have developed a system that visualizes the results of principal component analysis using multiple coordinated views and a rich set of user interactions. Our design philosophy is to support analysis of multivariate datasets through extensive interaction with the PCA output. To demonstrate the usefulness of our system, we performed a comparative user study with a known commercial system, SAS/INSIGHT's Interactive Data Exploration. Participants in our study solved a number of high‐level analysis tasks with each interface and rated the systems on ease of learning and usefulness. Based on the participants' accuracy, speed, and qualitative feedback, we observe that our system helps users to better understand relationships between the data and the calculated eigenspace, which allows the participants to more accurately analyze the data. User feedback suggests that the interactivity and transparency of our system are the key strengths of our approach. | false | false | [
"Dong Hyun Jeong",
"Caroline Ziemkiewicz",
"Brian D. Fisher",
"William Ribarsky",
"Remco Chang"
] | [] | [] | [] |
EuroVis | 2,009 | Lifted Domain Coloring | 10.1111/j.1467-8659.2009.01479.x | Complex‐valued functions are fundamental objects in complex analysis, algebra, differential geometry and in many other areas such as numerical mathematics and physics. Visualizing complex functions is a non‐trivial task since maps between two‐dimensional spaces are involved whose graph would be an unhandy submanifold in four‐dimensional space. The present paper improves the technique of “domain coloring” in several aspects: First, we lift domain coloring from the complex plane to branched Riemann surfaces, which are essentially the correct domain for most complex functions. Second, we extend domain coloring to the visualization of general 2‐valued maps on surfaces. As an application of such general maps we visualize the Gauss map of surfaces as domain colored plots and establish a link to current surface parametrization techniques and texture maps. Third, we adjust the color pattern in domain and in image space to produce higher quality domain colorings. The new color schemes specifically enhance the display of singularities, symmetries and path integrals, and give better qualitative measures of the complex map. | false | false | [
"Konstantin Poelke",
"Konrad Polthier"
] | [] | [] | [] |
EuroVis | 2,009 | Map Displays for the Analysis of Scalar Data on Cerebral Aneurysm Surfaces | 10.1111/j.1467-8659.2009.01459.x | Cerebral aneurysms result from a congenital or evolved weakness of stabilizing parts of the vessel wall and potentially lead to rupture and a life‐threatening bleeding. Current medical research concentrates on the integration of blood flow simulation results for risk assessment of cerebral aneurysms. Scalar flow characteristics close to the aneurysm surface, such as wall shear stress, form an important part of the simulation results. Aneurysms exhibit variable surface shapes with only few landmarks. Therefore, the exploration and mental correlation of different surface regions is a difficult task. In this paper, we present an approach for the intuitive and interactive overview visualization of near wall flow data that is mapped onto the surface of a 3D model of a cerebral aneurysm. We combine a multi‐perspective 2D projection map with a standard 3D visualization and present techniques to facilitate the correlation between a 3D model and a related 2D map. An informal evaluation with 4 experienced radiologists has shown that the map‐based overview actually improves the surface exploration. Furthermore, different color schemes were discussed and, as a result, an appropriate color scheme for the visual analysis of the wall shear stress is presented. | false | false | [
"Mathias Neugebauer",
"Rocco Gasteiger",
"Oliver Beuing",
"Volker Diehl",
"Martin Skalej",
"Bernhard Preim"
] | [] | [] | [] |
EuroVis | 2,009 | MultiClusterTree: Interactive Visual Exploration of Hierarchical Clusters in Multidimensional Multivariate Data | 10.1111/j.1467-8659.2009.01468.x | Visual analytics of multidimensional multivariate data is a challenging task because of the difficulty in understanding metrics in attribute spaces with more than three dimensions. Frequently, the analysis goal is not to look into individual records but to understand the distribution of the records at large and to find clusters of records with similar attribute values. A large number of (typically hierarchical) clustering algorithms have been developed to group individual records to clusters of statistical significance. However, only few visualization techniques exist for further exploring and understanding the clustering results. We propose visualization and interaction methods for analyzing individual clusters as well as cluster distribution within and across levels in the cluster hierarchy. We also provide a clustering method that operates on density rather than individual records. To not restrict our search for clusters, we compute density in the given multidimensional multivariate space. Clusters are formed by areas of high density. We present an approach that automatically computes a hierarchical tree of high density clusters. To visually represent the cluster hierarchy, we present a 2D radial layout that supports an intuitive understanding of the distribution structure of the multidimensional multivariate data set. Individual clusters can be explored interactively using parallel coordinates when being selected in the cluster tree. Furthermore, we integrate circular parallel coordinates into the radial hierarchical cluster tree layout, which allows for the analysis of the overall cluster distribution. This visual representation supports the comprehension of the relations between clusters and the original attributes. The combination of the 2D radial layout and the circular parallel coordinates is used to overcome the overplotting problem of parallel coordinates when looking into data sets with many records. We apply an automatic coloring scheme based on the 2D radial layout of the hierarchical cluster tree encoding hue, saturation, and value of the HSV color space. The colors support linking the 2D radial layout to other views such as the standard parallel coordinates or, in case data is obtained from multidimensional spatial data, the distribution in object space. | false | false | [
"Tran Van Long",
"Lars Linsen"
] | [] | [] | [] |
EuroVis | 2,009 | On Visualization and Reconstruction from Non-Uniform Point Sets using B-splines | 10.1111/j.1467-8659.2009.01447.x | In this paper we present a novel framework for the visualization and reconstruction from non‐uniform point sets. We adopt a variational method for the reconstruction of 3D non‐uniform data to a uniform grid of chosen resolution. We will extend this reconstruction to an efficient multi‐resolution uniform representation of the underlying data. Our multi‐resolution representation includes a traditional bottom‐up approach and a novel top‐down hierarchy for adaptive hierarchical reconstruction. Using a hybrid regularization functional we can improve the reconstruction results. Finally, we discuss further application scenarios and show rendering results to emphasize the effectiveness and quality of our proposed framework. By means of qualitative results and error comparisons we demonstrate superiority of our method compared to competing methods. | false | false | [
"Erald Vuçini",
"Torsten Möller",
"M. Eduard Gröller"
] | [
"HM"
] | [] | [] |
EuroVis | 2,009 | Preconceptions and Individual Differences in Understanding Visual Metaphors | 10.1111/j.1467-8659.2009.01442.x | Understanding information visualization is more than a matter of reading a series of data values; it is also a matter of incorporating a visual structure into one's own thinking about a problem. We have proposed visual metaphors as a framework for understanding high‐level visual structure and its effect on visualization use. Although there is some evidence that visual metaphors can affect visualization use, the nature of this effect is still ambiguous. We propose that a user's preconceived metaphors for data and other individual differences play an important role in her ability to think in a variety of visual metaphors, and subsequently in her ability to use a visualization. We test this hypothesis by conducting a study in which a participant's preconceptions and thinking style were compared with the degree to which she is affected by conflicting metaphors in a visualization and its task questions. The results show that metaphor compatibility has a significant effect on accuracy, but that factors such as spatial ability and personality can lessen this effect. We also find a complex influence of self‐reported metaphor preference on performance. These findings shed light on how people use visual metaphors to understand a visualization. | false | false | [
"Caroline Ziemkiewicz",
"Robert Kosara"
] | [] | [] | [] |
EuroVis | 2,009 | Quasi-interpolation on the Body Centered Cubic Lattice | 10.1111/j.1467-8659.2009.01446.x | This paper introduces a quasi‐interpolation method for reconstruction of data sampled on the Body Centered Cubic (BCC) lattice. The reconstructions based on this quasi‐interpolation achieve the optimal approximation order offered by the shifts of the quintic box spline on the BCC lattice. We also present a local FIR filter that is used to filter the data for quasi‐interpolation. We document the improved quality and fidelity of reconstructions after employing the introduced quasi‐interpolation method. Finally the resulting quasi‐interpolation on the BCC sampled data are compared to the corresponding quasi‐interpolation method on the Cartesian sampled data. | false | false | [
"Alireza Entezari",
"Mahsa Mirzargar",
"Leila Kalantari"
] | [] | [] | [] |
EuroVis | 2,009 | Scalable, Versatile and Simple Constrained Graph Layout | 10.1111/j.1467-8659.2009.01449.x | We describe a new technique for graph layout subject to constraints. Compared to previous techniques the proposed method is much faster and scalable to much larger graphs. For a graph with n nodes, m edges and c constraints it computes incremental layout in time O(n log n+m+c) per iteration. Also, it supports a much more powerful class of constraint: inequalities or equalities over the Euclidean distance between nodes. We demonstrate the power of this technique by application to a number of diagramming conventions which previous constrained graph layout methods could not support. Further, the constraint‐satisfaction method—inspired by recent work in position‐based dynamics—is far simpler to implement than previous methods. | false | false | [
"Tim Dwyer"
] | [] | [] | [] |
EuroVis | 2,009 | SDViz: A Context-Preserving Interactive Visualization System for Technical Diagrams | 10.1111/j.1467-8659.2009.01454.x | When performing daily maintenance and repair tasks, technicians require access to a variety of technical diagrams. As technicians trace components and diagrams from page‐to‐page, within and across manuals, the contextual information of the components they are analyzing can easily be lost. To overcome these issues, we have developed a Schematic Diagram Visualization System (SDViz) designed for maintaining and highlighting contextual information in technical documents, such as schematic and wiring diagrams. Our system incorporates various features to aid in the navigation and diagnosis of faults, as well as maintaining contextual information when tracing components/connections through multiple diagrams. System features include highlighting relationships between components and connectors, diagram annotation tools, the animation of flow through the system, a novel contextual blending method, and a variety of traditional focus+context visualization techniques. We have evaluated the usefulness of our system through a qualitative user study in which subjects utilized our system in diagnosing faults during a standard aircraft maintenance exercise. | false | false | [
"Insoo Woo",
"SungYe Kim",
"Ross Maciejewski",
"David S. Ebert",
"Timothy D. Ropp",
"Krystal M. Thomas"
] | [] | [] | [] |
EuroVis | 2,009 | Selecting good views of high-dimensional data using class consistency | 10.1111/j.1467-8659.2009.01467.x | Many visualization techniques involve mapping high‐dimensional data spaces to lower‐dimensional views. Unfortunately, mapping a high‐dimensional data space into a scatterplot involves a loss of information; or, even worse, it can give a misleading picture of valuable structure in higher dimensions. In this paper, we propose class consistency as a measure of the quality of the mapping. Class consistency enforces the constraint that classes of n–D data are shown clearly in 2–D scatterplots. We propose two quantitative measures of class consistency, one based on the distance to the class's center of gravity, and another based on the entropies of the spatial distributions of classes. We performed an experiment where users choose good views, and show that class consistency has good precision and recall. We also evaluate both consistency measures over a range of data sets and show that these measures are efficient and robust. | false | false | [
"Mike Sips",
"Boris Neubert",
"John P. Lewis",
"Pat Hanrahan"
] | [] | [] | [] |
EuroVis | 2,009 | Semi-Automatic Time-Series Transfer Functions via Temporal Clustering and Sequencing | 10.1111/j.1467-8659.2009.01472.x | When creating transfer functions for time‐varying data, it is not clear what range of values to use for classification, as data value ranges and distributions change over time. In order to generate time‐varying transfer functions, we search the data for classes that have similar behavior over time, assuming that data points that behave similarly belong to the same feature. We utilize a method we call temporal clustering and sequencing to find dynamic features in value space and create a corresponding transfer function. First, clustering finds groups of data points that have the same value space activity over time. Then, sequencing derives a progression of clusters over time, creating chains that follow value distribution changes. Finally, the cluster sequences are used to create transfer functions, as sequences describe the value range distributions over time in a data set. | false | false | [
"Jonathan Woodring",
"Han-Wei Shen"
] | [] | [] | [] |
EuroVis | 2,009 | Smooth Stream Surfaces of Fourth Order Precision | 10.1111/j.1467-8659.2009.01462.x | We introduce a novel technique for the construction of smooth stream surfaces of 4th order precision. While common stream surface techniques use linear interpolation for generating seed points for new streamlines in the refinement phase, we use Hermite interpolation. The derivatives needed for Hermite interpolation are obtained by integration along the streamlines. This yields stream surfaces of4th order precision. Additionally, we analyse the accuracy ofthe well known Hultquist approach and our new algorithm and proof that Hultquist's method is exact for linear vector fields. We compare both methods using the well known distance based and a novel error based refinement strategy. Our resulting surface is C1 ‐continuous, enabling improved rendering among other benefits. | false | false | [
"Dominic Schneider",
"Alexander Wiebel",
"Gerik Scheuermann"
] | [] | [] | [] |
EuroVis | 2,009 | Splatting the Lines in Parallel Coordinates | 10.1111/j.1467-8659.2009.01476.x | In this paper, we propose a novel splatting framework for clutter reduction and pattern revealing in parallel coordinates. Our framework consists of two major components: a polyline splatter for cluster detection and a segment splatter for clutter reduction. The cluster detection is performed by splatting the lines one by one into the parallel coordinates plots, and for each splatted line we enhance its neighboring lines and suppress irrelevant ones. To reduce visual clutter caused by line crossings and overlappings in the clustered results, we provide a segment splatter which represents each polyline by one segment and splats these segments with different speeds, colors, and lengths from the leftmost axis to the rightmost axis. Users can interactively control both the polyline splatting and the segment splatting processes to emphasize the features they are interested in. The experimental results demonstrate that our framework can effectively reveal some hidden patterns in parallel coordinates. | false | false | [
"Hong Zhou 0004",
"Weiwei Cui",
"Huamin Qu",
"Yingcai Wu",
"Xiaoru Yuan",
"Wei Zhuo 0001"
] | [] | [] | [] |
EuroVis | 2,009 | The Chinese Room: Visualization and Interaction to Understand and Correct Ambiguous Machine Translation | 10.1111/j.1467-8659.2009.01443.x | We present The Chinese Room, a visualization interface that allows users to explore and interact with a multitude of linguistic resources in order to decode and correct poor machine translations. The target users of The Chinese Room are not bilingual and are not familiar with machine translation technologies. We investigate the ability of our system to assist such users in decoding and correcting faulty machine translations. We found that by collaborating with our application, end‐users can overcome many difficult translation errors and disambiguate translated passages that were otherwise baffling. We also examine the utility of our system to machine translation researchers. Anecdotal evidence suggests that The Chinese Room can help such researchers develop better machine translation systems. | false | false | [
"Joshua Albrecht",
"Rebecca Hwa",
"G. Elisabeta Marai"
] | [] | [] | [] |
EuroVis | 2,009 | The Gödel Engine - An interactive approach to visualization in general relativity | 10.1111/j.1467-8659.2009.01470.x | We present a methodical new approach to visualize the aspects of general relativity from a self‐centered perspective. We focus on the visualization of the Gödel universe, which is an exact solution to Einstein's field equations of general relativity. This model provides astounding features such as the existence of an optical horizon and the possibility of time travel. Although we know that our universe is not of Gödel type, we can – using this solution to Einstein's equations – visualize and understand the effects resulting from the theory of relativity, which itself has been verified on the large scale in numerous experiments over the last century. We derive the analytical solution to the geodesic equations of Gödel's universe for special initial conditions. Along with programmable graphics hardware we achieve a tremendous speedup for the visualization of general relativity. This enables us to interactively explore the physical aspects and optical effects of Gödel's universe. We also demonstrate how the analytical solution enables dynamic lighting with local illumination models. Our implementation is tailored for Gödel's universe and five orders of magnitude faster than previous approaches. It can be adapted to manifolds for which an analytical expression of the propagation of light is available. | false | false | [
"Frank Grave",
"Thomas Müller 0005",
"Carsten Dachsbacher",
"Günter Wunner"
] | [] | [] | [] |
EuroVis | 2,009 | Visual Analysis of Brain Activity from fMRI Data | 10.1111/j.1467-8659.2009.01458.x | Classically, analysis of the time‐varying data acquired during fMRI experiments is done using static activation maps obtained by testing voxels for the presence of significant activity using statistical methods. The models used in these analysis methods have a number of parameters, which profoundly impact the detection of active brain areas. Also, it is hard to study the temporal dependencies and cascading effects of brain activation from these static maps. In this paper, we propose a methodology to visually analyze the time dimension of brain function with a minimum amount of processing, allowing neurologists to verify the correctness of the analysis results, and develop a better understanding of temporal characteristics of the functional behaviour. The system allows studying time‐series data through specific volumes‐of‐interest in the brain‐cortex, the selection of which is guided by a hierarchical clustering algorithm performed in the wavelet domain. We also demonstrate the utility of this tool by presenting results on a real data‐set. | false | false | [
"Firdaus Janoos",
"Boonthanome Nouanesengsy",
"Raghu Machiraju",
"Han-Wei Shen",
"Steffen Sammet",
"Michael V. Knopp",
"István Ákos Mórocz"
] | [] | [] | [] |
EuroVis | 2,009 | Visualisation of Sensor Data from Animal Movement | 10.1111/j.1467-8659.2009.01469.x | A new area of biological research is identifying and grouping patterns of behaviour in wild animals by analysing data obtained through the attachment of tri‐axial accelerometers. As these recording devices become smaller and less expensive their use has increased. Currently acceleration data are visualised as 2D time series plots, and analyses are based on summary statistics and the application of Fourier transforms. We develop alternate visualisations of this data so as to analyse, explore and present new patterns of animal behaviour. Our visualisations include interactive spherical scatterplots, spherical histograms, clustering methods, and feature‐based state diagrams of the data. We study the application of these visualisation methods to accelerometry data from animal movement. The reaction of biologists to these visualisations is also reported. | false | false | [
"Edward Grundy",
"Mark W. Jones",
"Robert S. Laramee",
"Rory P. Wilson",
"Emily L. C. Shepard"
] | [
"BP"
] | [] | [] |
EuroVis | 2,009 | Visualization of vessel movements | 10.1111/j.1467-8659.2009.01440.x | We propose a geographical visualization to support operators of coastal surveillance systems and decision making analysts to get insights in vessel movements. For a possibly unknown area, they want to know where significant maritime areas, like highways and anchoring zones, are located. We show these features as an overlay on a map. As source data we use AIS data: Many vessels are currently equipped with advanced GPS devices that frequently sample the state of the vessels and broadcast them. Our visualization is based on density fields that are derived from convolution of the dynamic vessel positions with a kernel. The density fields are shown as illuminated height maps. Combination of two fields, with a large and small kernel provides overview and detail. A large kernel provides an overview of area usage revealing vessel highways. Details of speed variations of individual vessels are shown with a small kernel, highlighting anchoring zones where multiple vessels stop. Besides for maritime applications we expect that this approach is useful for the visualization of moving object data in general. | false | false | [
"Niels Willems",
"Huub van de Wetering",
"Jarke J. van Wijk"
] | [] | [] | [] |
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