EuroVA: International Workshop on Visual Analytics

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Comparative Visual Analysis of Cross-Linguistic Features
(The Eurographics Association, 2010) Rohrdantz, Christian; Mayer, Thomas; Butt, Miriam; Plank, Frans; Keim, Daniel A.; Joern Kohlhammer and Daniel Keim
Approaches in Visual Analytics have so far been developed for a wide array of research areas, mainly with a focus on industrial or business applications. The field of linguistics, however, has only marginally incorporated visualizations in its research, e.g. using simple tree representations, attribute-value matrices or network analyses. This paper suggests a new interesting field of application demonstrating how Visual Analytics is able to support linguists in their research. We show this with respect to one concrete linguistic phenomenon, named Vowel Harmony, where visual analysis allows an at-a-glance comparison across a variety of languages. Our approach covers the entire pipeline of Visual Analytics methodology: data processing, feature extraction and the creation of an interactive visual representation. Our results allow for a novel approach to linguistic investigation in that we enable an at-a-glance analysis of whether vowel harmony is present in a language and, beyond that, a precise indication of the particular type of vowel interdependence and patterning in a given language.
Sensemaking in Visual Analytics: Processes and Challenges
(The Eurographics Association, 2010) Attfield, Simon J.; Hara, Sukhvinder K.; Wong, B. L. William; Joern Kohlhammer and Daniel Keim
Since Visual Analytic systems support human sensemaking it is essential that such systems are designed with characteristics of this process in mind. Drawing on our previous work with lawyers and reports from experienced fraud investigators we describe the nature of the cognitive work to be supported. We describe the cognitive work domain in terms of its data characteristics, and develop a model of the sensemaking as basis for discussing a distinction between 'naturalistic' and 'normative' sensemaking with a particular emphasis on inference types and the potential for bias. We also report results from a questionnaire-based case study designed to elicit memorable incidents from fraud investigators' experiences. Given the legal context the case study exemplifies skills and strategies that are necessary in order to achieve normative and defensible sensemaking under pressure of highvolume datasets.
Interactive Visual Analysis of Families of Surfaces: An Application to Car Race and Car Setup
(The Eurographics Association, 2010) Matkovic, Kresimir; Gracanin, Denis; Splechtna, Reiner; Hauser, Helwig; Joern Kohlhammer and Daniel Keim
Modern simulations often produce time series, or even functions of two variables as outputs for single attributes. Such complex data require carefully chosen and designed analysis procedures and the corresponding data model. The use of previously developed curve and surface views provides strong support for visual exploration and analysis of complex data. In this paper we describe how interactive visual analysis can support users in getting insight into complex data. The case study, based on TORCS 3D racing cars simulator, illustrates our approach and its successful application to a real world problem. The analysis of the car parameters and driving performances during races provides an insight and explanation for race results. That insight is then used to fine-tune car parameters to achieve better driving performance.
Finding Arbitrary Shaped Clusters with Related Extents in Space and Time
(The Eurographics Association, 2010) Pölitz, Christian; Andrienko, Gennady; Andrienko, Natalia; Joern Kohlhammer and Daniel Keim
The paper deals with density-based clustering of events, i.e. objects positioned in space and time, such as occurrences of earthquakes, forest fires, mobile phone calls, or photos with geographical references. Finding concentrations of events in space and time can help to discover interesting places and time periods. The spatial and temporal properties of event clusters, in particular, their spatial and temporal extents and densities, can be related to each other. Therefore, we suggest a two-step clustering method that considers relations of the spatial and temporal dimension. We demonstrate the work of the method on several examples of real data.
Combining Details of the Chi-Square Goodness-of-Fit Test with Multivariate Data Visualization
(The Eurographics Association, 2010) May, Thorsten; Davey, James; Kohlhammer, Jörn; Joern Kohlhammer and Daniel Keim
In this work, we combine KVMaps, a visualization technique presented in [May07] for the visualization of statistical aggregations in multivariate contingency tables, with the measures used for the statistical Chi-Square goodness-of-fit test. Goodness-of-fit tests are used to check whether a given distribution of values matches an expected distribution. A single test statistic is calculated to represent the deviation of the complete dataset. By visualizing the deviations for all entries in the contingency table, it is possible to identify the patterns in the distribution of data items, which contribute most to the overall deviation of the dataset. We present two use cases to illustrate how the information about the patterns can be used.
Smart Query Definition for Content-Based Search in Large Sets of Graphs
(The Eurographics Association, 2010) Landesberger, Tatiana von; Bremm, Sebastian; Bernard, Jürgen; Schreck, Tobias; Joern Kohlhammer and Daniel Keim
Graphs are used in various application areas such as chemical, social or shareholder network analysis. Finding relevant graphs in large graph databases is thereby an important problem. Such search starts with the definition of the query object. Defining the query graph quickly and effectively so that it matches meaningful data in the database is difficult. In this paper, we introduce a system, which guides the user through the process of query graph building. We propose three approaches for graph definition. First, query by example selection starting from an overview of the graph types in the database, second query by sketch combining graph building blocks (i.e., topologic subgraphs) with free graph drawing, and third a combination of both approaches. In all three query definition ways, we support the user with intelligent, data dependent recommendations. It covers the whole spectrum of building parameters such as representative examples, frequent building blocks, or common graph size.
Policy-making in a Complex World: Can Visual Analytics Help?
(The Eurographics Association, 2010) Osimo, David; Lampathaki, Fenareti; Charalabidis, Yannis; Joern Kohlhammer and Daniel Keim
As government are moving their focus from service provision to regulation, socio-economic issue are revealing more complex than ever to regulate. Traditional top-down and linear models for dealing with risks proved uneffective, as the financial crisis has shown. In recent years, new ICT tools have emerged that take better account of complexity and wicked problems, namely by augmenting human intelligence rather than trying to substitute for it: for example, social networking, crowdsourcing, social simulation and visual analytics. Yet these tools are far from being widespread and the related research fields are still fragmented. The CROSSROAD project, co-funded by the European Commission, aims at drawing a common research agenda in the field of ICT for Governance and Policy Modelling, including approaches such as visual analytics, that enable the identification of unexpected risks and the augmenting of human intelligence in dealing with large amounts of data. This paper presents the approach and the first results of the project, with the aim to start a wider discussion with the visual analytics community on future research issues.
DYNEVI - DYnamic News Entity Visualization
(The Eurographics Association, 2010) Wanner, Franz; Schaefer, Matthias; Leitner-Fischer, Florian; Zintgraf, Fabian; Atkinson, M.; Keim, Daniel A.; Joern Kohlhammer and Daniel Keim
Dynamic news entity visualization shows an implementation of visualizing news entity data to give an overview as well as to display emerging and vanishing news topics. We present a robust and dynamic visualization system with case studies that show its benefits and high functionality.
Visual Analytics in Software Maintenance: Challenges and Opportunities
(The Eurographics Association, 2010) Telea, Alexandru; Ersoy, Ozan; Voinea, Lucian; Joern Kohlhammer and Daniel Keim
Visual analytics (VA) is an emerging science at the crossroads of data and information visualization, graphics, data mining, and knowledge representation, with many successful applications in engineering, business and finance, security, geosciences, and e-governance and health. Tools using visualization, data mining, and data analysis are also prominently present in a different field: software maintenance. However, an integrated VA is relatively new for this field. In this paper, we discuss the specific challenges and particularities of applying VA in software engineering, highlight the added value of a VA approach, as distilled by us from several large-scale software engineering industrial projects.
Visual Analytics to Check Marine Containers in the Eritr\@c Project
(The Eurographics Association, 2010) Aupetit, Michaël; Allano, Lorène; Espagnon, Isabelle; Sannie, Guillaume; Joern Kohlhammer and Daniel Keim
The Eritr@c project is a European project aiming at developing an inspection system to control marine containers for illicit or dangerous materials. The system is made of a neutron generator, a set of sensors, and an information system to process the data. One of the main parts of the system is an interactive visualization interface whose goal is to help custom officers to decide if a container must be opened for deeper check of its content. In this paper, we present the components of this visual interface and their use for analytic reasoning.
Utilizing Treemaps for Multicriterial Search of 3D Objects
(The Eurographics Association, 2010) Petkos, Georgios; Darlagiannis, Vasilios; Moustakas, Konstantinos; Tzovaras, Dimitrios; Joern Kohlhammer and Daniel Keim
We propose a treemap based interface for presentation of search results according to multiple search criteria. Different colors are used to represent the relevance of each item in the database according to the different search criteria, while at the same time the treemap based representation allows the user to visually identify relevant groups of data, exploiting the hierarchical organization of the items in the database. Items are ranked according to each criterion and an aggregate ranking is computed using the Borda algorithm. Furthermore, appropriate interaction mechanisms are provided in order to assist the user in refining the presentation of the returned items and weigh the contribution of different criteria for retrieving combined search results. The Princeton benchmark 3D object database is used for this study, nevertheless the technique presented is appropriate for any multicriterial search application and in particular in cases where the data is organized hierarchically.
Stress Maps: Analysing Local Phenomena in Dimensionality Reduction Based Visualisations
(The Eurographics Association, 2010) Seifert, Christin; Sabol, Vedran; Kienreich, Wolfgang; Joern Kohlhammer and Daniel Keim
Challenges in Visual Analytics frequently involve massive repositories, which do not only contain a large number of information artefacts, but also a high number of relevant dimensions per artefact. Dimensionality reduction algorithms are commonly used to transform high-dimensional data into low- dimensional representations which are suitable for visualisation purposes. For example, Information Landscapes visualise high-dimensional data in two dimensions using distance-preserving projection methods. The inaccuracies introduced by such methods are usually expressed through a global stress measure which does not provide insight into localised phenomena. In this paper, we propose the use of Stress Maps, a combination of heat maps and information landscapes, to support algorithm development and optimization based on local stress measures. We report on an application of Stress Maps to a scalable text projection algorithm and describe two categories of problems related to localised stress phenomena which we have identified using the proposed method.
Capturing Reasoning Process through User Interaction
(The Eurographics Association, 2010) Dou, Wenwen; Ribarsky, William; Chang, Remco; Joern Kohlhammer and Daniel Keim
In recent years, visual analytics has taken an important role in solving many types of complex analytical problems that require deep and specific domain knowledge from users. While the analysis products generated by these expert users are of great importance, how these users apply their domain expertise in using the visualization to validate their hypotheses and arrive at conclusions is often just as invaluable. Recent research efforts in capturing an expert's reasoning process using a visualization have shown that some of a user's analysis process is indeed recoverable. However, there does not exist a generalizable principle that explains the success of these domainspecific systems in capturing the user's reasoning process. In this paper, we present a framework that examines two aspects of the capturing process. First, we inspect how a user's reasoning process can be captured by utilizing van Wijk's operational model of visualization. Second, we evaluate the likelihood of success in capturing a user's interactions in a visualization by introducing three criteria designed for disambiguating the meanings behind the interactions. Various visualization systems in the visualization and HCI communities are examined for the purpose of demonstrating the impact of the three criteria.
Does Jason Bourne need Visual Analytics to catch the Jackal?
(The Eurographics Association, 2010) Bertone, Alessio; Lammarsch, Tim; Turic, Thomas; Aigner, Wolfgang; Miksch, Silvia; Joern Kohlhammer and Daniel Keim
Visual Analytics is a relatively new field which tries to combine and intertwine visual and analytical methods in an interactive manner. Because of the complex structure of time, the application of visual analytics methods to time-oriented data is a very promising approach for insight generation. To show how this can be applied, on top of real world data we created a fictitious scenario where even one of Ludlum's heroes, Jason Bourne, could take advantage of the collaboration between visual and analytical methods.
A Framework for the Multi-Temporal Analysis of Land Cover Change using Visual Analytics
(The Eurographics Association, 2011) Kinkeldey, C.; Schiewe, J.; Silvia Miksch and Giuseppe Santucci
Land cover change analysis serves as a basis for planning processes in a wide range of applications. For this task, the use of remote sensing data has become more popular over the last decades. However, despite much research in the field of change analysis based on remote sensing data, effective and efficient methods are not available yet. In order to get closer to this goal, we propose the application of Visual Analytics to this field combining computational methods with interactive visualization. We expect that the close integration of the user into the change analysis process will lead to more powerful solutions. However, for the design of tools following this approach we see the need for instruments to formalize workflows. For this reason, we are developing a framework that allows for a systematic workflow description. This contribution presents the basic concept of the framework including an exemplary application.
Contingency Wheel: Visual Analysis of Large Contingency Tables
(The Eurographics Association, 2011) Alsallakh, Bilal; Groeller, Eduard; Miksch, Silvia; Suntinger, Martin; Silvia Miksch and Giuseppe Santucci
We present the Contingency Wheel, a visual method for finding and analyzing associations in a large nxm contingency table with m less than 100 and n being two to three orders of magnitude larger than m. The method is demonstrated on a large table from the Book-Crossing dataset, which counts the number of ratings each book received from each country. It enables finding books that received a disproportionately high number of ratings from a specific country. It further allows to visually analyze what these books have in common, and with which countries they are also highly associated. Pairs of similar countries can further be identified (in the sense that many books are associated with both countries). Compared with existing visual methods, our approach enables analyzing and gaining insight into larger tables.
Interactive Analysis of Object Group Changes over Time
(The Eurographics Association, 2011) Bremm, S.; Landesberger, T. von; Andrienko, G.; Andrienko, N.; Schreck, Tobias; Silvia Miksch and Giuseppe Santucci
The analysis of time-dependent data is an important task in various application domains. Often, the analyzed data objects belong to groups. The group memberships may stem from natural arrangements (e.g., animal herds), or may be constructed during analysis (e.g., by clustering). Group membership may change over time. Therefore, one important analytical aspect is to examine these changes (e.g., which herds change members and when). In this paper, we present a technique for visual analysis of group changes over time. We combine their visualization and automatic analysis. Interactive functions allow for tracking the data changes over time on group, set and individual level. We also consider added and removed objects (e.g., newly born or died animals). For large time series, automatic data analysis selects interesting time points and group changes for detailed examination. We apply our approach on the VAST 2008 challenge data set revealing new insights.
Adaptive Interactive Multi-Resolution Computational Steering for Complex Engineering Systems
(The Eurographics Association, 2011) Matkovic, K.; Gracanin, D.; Jelovic, M.; Cao, Y.; Silvia Miksch and Giuseppe Santucci
Computational steering integrates modeling, computation, data analysis, visualization, and data input components of a simulation. Since the simulation space is, in general, very large and continuous, selecting discrete simulation points that can reasonably represent the whole simulation space is difficult. We need to interpolate the missing values and cover a continuous region of interest in the simulation space. We describe an approach that, in an iterative manner, allows a domain expert to interactively select data points (design of experiments), approximate the values in a continuous region of the simulation space (regression) and automatically find the best points in that continuous region based on the specified constraints and objectives (optimization), using the regression and aggregated data. Once the objectives are found, the data points in the neighborhood of the objective are generated by the simulation tool thus providing a denser coverage of the regions of interest.
Understanding the Role and Value of Interaction: First Steps
(The Eurographics Association, 2011) Aigner, W.; Silvia Miksch and Giuseppe Santucci
Visual Analytics strongly emphasizes the importance of interaction. However, until now, interaction is only sparingly treated as subject matter on its own. How and why interactivity is beneficial to gain insight and make decisions is mostly left in the dark. Due to this lack of initial direction, it seems important to make further attempts in facilitating a deeper understanding of the concept of interactivity. Therefore, different perspectives towards interactivity are discussed and cognitive theories and models are investigated. The main aim of this paper is to broaden the view on interaction and spark further discussion towards a sound theoretical grounding for the field.
Data Driven Color Mapping
(The Eurographics Association, 2011) Eisemann, Martin; Albuquerque, Georgia; Magnor, Marcus; Silvia Miksch and Giuseppe Santucci
In this paper we present a simple, yet effective method to map data set values of different distributions to a color map in order to reveal interesting structures. We make use of an ordering and a simple projection technique to transform the data set before color mapping. Our transformation yields convincing results for various distributions. It also removes the burden from the user to test several mappings beforehand. A simple angular interpolation technique allows to project the data values of the visualization as desired, interactively.

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