EuroVisPosters2017

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https://diglib.eg.org/handle/10.2312/2631437

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Visual Analysis of Geolocated Echo Chambers in Social Media
(The Eurographics Association, 2017) Hundt, Michael; Schneider, Bruno; El-Assady, Mennatallah; Keim, Daniel A.; Diehl, Alexandra; Anna Puig Puig and Tobias Isenberg
In news media, echo chambers refer to situations in which information is amplified or reinforced by communication and repetition. The characteristic of an echo chamber is, therefore, the absence of controversial discussions and a narrow set of opinions about a topic. We propose the use of Visual Analytics to describe spatiotemporal distributions of echo chambers using Twitter data, for specific geolocated events, such as concerts, strikes, demonstrations, etc. We analyze the echo chambers for Boston Marathon Bombing that took place on April 15, 2013. The social groups are displayed by a matrix view containing all connected components of the tweet mention graphs. To identify similar opinions, as well as, the diversity of topics in a discussion, we apply text classification and sentiment analysis. Lastly, we present initial findings based on real-world data.
Evaluating Cognitive Load: Force-directed Layout vs. Chord Layout
(The Eurographics Association, 2017) Moses, Ricarda; Humayoun, Shah Rukh; AlTarawneh, Ragaad; Ebert, Achim; Anna Puig Puig and Tobias Isenberg
Understanding cognitive processes during the interaction with visualizations, specifically limitations of working memory, opens a new perspective on evaluations and encourages a more user-centric design approach. In a user study we evaluated two graph data visualization approaches (i.e., the force-directed layout and the Chord layout) using a cognitive load questionnaire to assess the three load types: intrinsic, extraneous, and germane load. Tasks were designed to encourage insight and sensemaking in the participants during the evaluation. This type of evaluation helps to assess the users' mental processes during sensemaking and graph reading in the underlying layouts. Further, such study findings would help visualization designers in choosing the appropriate layout type for their graph data.
Interactive Lens for Effective Time-Series Animation
(The Eurographics Association, 2017) Chen, Yang; Yang, Jing; Zhao, Ye; Anna Puig Puig and Tobias Isenberg
We present a lens-based approach to explore animated data visualizations that involve time-series. The core of the approach lies in a novel combination of Lagrangian and Eulerian lenses, which allows us to leverage their complementary advantages to analyze data elements in complex spatial-temporal space. Film art techniques are employed to advance the way shifting the elements across different time and spaces. We illustrate the approach using animated bubble charts.
DaaG: Visual Analytics Clustering Using Network Representation
(The Eurographics Association, 2017) Alcaide, Daniel; Aerts, Jan; Anna Puig Puig and Tobias Isenberg
Finding useful patterns in datasets has attracted considerable interest in the field of visual analytics. One of the most common solutions is the identification and representation of clusters. In this work, we propose a visual analytics clustering methodology for guiding the user in the exploration and detection of clusters in a dataset. We thereby combine the homological algebra with a graphical representation of the clustered dataset as a network into one coherent framework. Our approach entails displaying the results of the heuristics to users, providing a setting from which to start the exploration and data analysis.
BitConduite: Visualizing and Analyzing Activity on the Bitcoin Network
(The Eurographics Association, 2017) Kinkeldey, Christoph; Fekete, Jean-Daniel; Isenberg, Petra; Anna Puig Puig and Tobias Isenberg
BitConduite is a system we are developing for the visual exploration of financial activity on the Bitcoin network. Bitcoin is the largest digital pseudo-currency worldwide and its study is of increasing interest and importance to economists, bankers, policymakers, and law enforcement authorities. All financial transactions in Bitcoin are available in an openly accessible online ledger-the (Bitcoin) blockchain. Yet, the open data does not lend itself easily to an analysis of how different individuals and institutions-or entities on the network-actually use Bitcoin. Our system BitConduite offers a data transformation back end that gives us an entity-based access to the blockchain data and a visualization front end that supports a novel high-level view on transactions over time. In particular, it facilitates the exploration of activity through filtering and clustering interactions. We are developing our system with experts in economics and will conduct a formal user study to assess our approach of Bitcoin activity analysis.
Hypenet: Visualizing Dynamic Hypergraphs
(The Eurographics Association, 2017) Valdivia, Paola; Buono, Paolo; Fekete, Jean-Daniel; Anna Puig Puig and Tobias Isenberg
We present Hypenet, a novel technique to visualize dynamic hypergraphs. Such structures can model multiple types of data, such as computer networks with multiple destination addresses (multicast) or co-authorship networks with multiple authors per article. Hypenet visualizes the evolving topology of the hypergraph in a compact way, allowing users to detect patterns and inconsistencies. We describe our technique and show how it applies to the case of the history of publications of the Eurovis conference, revealing interesting patterns that can contribute to tell a story about data and create hypotheses.
Visual Analytics of Global Parameters in Simulation Ensembles of ODE-based Excitable Network Dynamics
(The Eurographics Association, 2017) Ngo, Quynh Quang; Hütt, Marc-Thorsten; Linsen, Lars; Anna Puig Puig and Tobias Isenberg
The role of network topology on the dynamics in simulations that are executed on the network is a central question in the field of network science. However, the influence of the topology is affected by the global dynamical simulation parameters. To investigate this impact of the parameter settings, multiple simulation runs are executed with different settings. Moreover, since the outcome of a single simulation run also depends on the randomly chosen start configurations, multiple runs with the same settings are carried out, as well. We present a visual approach to analyze the role of topology in such an ensemble of simulation ensembles. We use the dynamics of an excitable network implemented in the form of a coupled ordinary differential equation (ODE) following the FitzHugh-Nagumo (FHN) model and modular network topologies.
Structuring and Visualizing Knowledge in Soil Science
(The Eurographics Association, 2017) Stößel, Bastian; Rabot, Eva; Richter, Felix; Weller, Ulrich; Vogel, Hans-Jörg; Anna Puig Puig and Tobias Isenberg
Soil is a highly complex system. Myriads of articles are published each year on soil processes and properties, interactions between them and management practices influencing them. But, because of the sheer mass of information and the complexity of the system, it is hard to maintain an overview of reliable information on these interactions and their sensitivity to external forcings. To collect, structure and visualize scientific results on functional relationships, we develop a system based on a mySQL database, a soil thesaurus and two JavaScript-driven visualizations. The system is fueled by a comprehensive soil literature review and currently being organized as a community effort to improve the understanding of the soil system and support users in finding information on functional relationships and knowledge gaps in soil science.
Visually Analyzing Parameter Influence on Optical Coherence Tomography Data in Ophthalmology
(The Eurographics Association, 2017) Röhlig, Martin; Luboschik, Martin; Prakasam, Ruby Kala; Stachs, Oliver; Schumann, Heidrun; Anna Puig Puig and Tobias Isenberg
Optical coherence tomography (OCT) enables noninvasive high-resolution imaging of the human retina and therefore, plays a fundamental role in detecting a wide range of ocular diseases. Yet, OCT data often vary in quality and show strong parameter dependencies. We propose a visual analysis approach to support users in understanding the influence of parameters on different aspects of the data. First, we outline the problem scope and derive requirements for a visual parameter analysis of OCT data. Second, we devise matched visual designs that disclose the impact of specific parameter values and the relationships between multiple parameter settings. With our systematic approach we aim at helping users in choosing suitable parameter settings and finding a balance between acquisition effort and data quality.
A Visual Approach for Text Analysis Using Multiword Topics
(The Eurographics Association, 2017) Mun, Seongmin; Desagulier, Guillaume; Lee, Kyungwon; Anna Puig Puig and Tobias Isenberg
Topics in a text corpus include features and information; visualizing these topics can improve a user's understanding of the corpus. Topics can be broadly divided into two categories: those whose meaning can be described in one word and those whose meaning in expressed through a combination of words. The latter type can be described as multiword expressions and consists of a combination of different words. However, analysis of multiword topics requires systematic analysis to extract accurate topic results. Therefore, we propose a visual system that accurate extracts topic results with multiple word combinations. For this study, we utilize the text of 957 speeches from 43 U.S. presidents (from George Washington to Barack Obama) as corpus data. Our visual system is divided into two parts: First, our system refines the database by topic, including multiword topics. Through data processing, we systematically analyze the accurate extraction of multiword topics. In the second part, users can confirm the details of this result with a word cloud and simultaneously verify the result with the raw corpus. These two parts are synchronized and the desired value of N in the N-gram model, topics, and presidents examined can be altered. In this case study of U.S. presidential speech data, we verify the effectiveness and usability of our system.
Power Efficiency of Volume Raycasting on Mobile Devices
(The Eurographics Association, 2017) Heinemann, Moritz; Bruder, Valentin; Frey, Steffen; Ertl, Thomas; Anna Puig Puig and Tobias Isenberg
Power efficiency is one of the most important factors for the development of compute-intensive applications in the mobile domain. In this work, we evaluate and discuss the power consumption of a direct volume rendering app based on raycasting on a mobile system. For this, we investigate the influence of a broad set of algorithmic parameters, which are relevant for performance and rendering quality, on the energy usage of the system. Additionally, we compare an OpenCL implementation to a variant using OpenGL. By means of a variety of examples, we demonstrate that numerous factors can have a significant impact on power consumption. In particular, we also discuss the underlying reasons for the respective effects.
Towards an Adaptive Framework for Real-Time Visualization of Streaming Big Data
(The Eurographics Association, 2017) Khan, Amin M.; Gonçalves, Daniel; Leão, Duarte C.; Anna Puig Puig and Tobias Isenberg
Big data poses new challenges and the need for flexible, interactive, and dynamic visualization techniques. Existing approaches, especially in enterprise data visualization with static graphics or interactive dashboards, are limited at the scale of big data, given the volume and diversity of data to consider. Streaming data further compounds on the problem with the need for real-time analytics and visualizations. On the data acquisition and collection side of things, traditional business analytics platforms are being extended with support for technologies such as Apache Spark for improvement in performance. However, for real-time data visualization for streaming data, it is necessary to go beyond Apache Spark with in-memory processing and new data visualization idioms. We propose a framework for the dynamic visualization of real-time streaming big data, resilient to both its volume and rate of change. Some of the different directions we explore include: (a) the efficient processing and consumption of streaming data; (b) the automated detection of relevant changes in the data stream, highlighting entities that merit a detailed analysis; (c) the choice of the best idioms to visualize big data, possibly leading to the development of new visualization idioms; (d) real-time visualization changes.
Quantitative Comparison of Treemap Techniques for Time-Dependent Hierarchies
(The Eurographics Association, 2017) Vernier, Eduardo Faccin; Comba, Joao L. D.; Telea, Alex C.; Anna Puig Puig and Tobias Isenberg
Hierarchical data in which leaf nodes have associated attributes appear in several applications. Rectangular Treemaps (RTs) were designed to display this type of data by tightly packing cells representing the tree nodes, with additional information stored in the cell sizes and/or colors. For dynamic hierarchies, RTs have to obey several requirements regarding the optimal aspect ratio of cells, but also the stability of layout in presence of data changes. While static RTs studied the first requirement well, far less information is available on how RTs behave vs both requirements for dynamic data. We study how four known RT methods compare over several real-world dynamic hierarchies, and highlight how recent RT methods can be adapted to effectively handle optimal cell ratios and stability.
Uncertainty Visualization of Stenotic Regions in Vascular Structures
(The Eurographics Association, 2017) Ristovski, Gordan; Hahn, Horst K.; Linsen, Lars; Anna Puig Puig and Tobias Isenberg
Stenosis refers to the thinning of the inner surface (lumen) of vascular structures. Detecting stenoses and correctly estimating their degree is crucial in clinical settings for proper treatment planning. Such a planning involves a visual assessment, which in case of vascular structures is frequently based on 3D visual representations of the vessels. However, since vessel segmentation is affected by various sources of errors and noise in the imaging and image processing pipeline, it is crucial to capture and visually convey the uncertainty in a 3D visual representation. We propose a novel approach for visualizing the shape deviation of different probability levels in vascular data, where the probability levels are computed from a probabilistic segmentation approach.
A High-Dimensional Data Quality Metric using Pareto Optimality
(The Eurographics Association, 2017) Post, Tobias; Wischgoll, Thomas; Hamann, Bernd; Hagen, Hans; Anna Puig Puig and Tobias Isenberg
The representation of data quality within established high-dimensional data visualization techniques such as scatterplots and parallel coordinates is still an open problem. This work offers a scale-invariant measure based on Pareto optimality that is able to indicate the quality of data points with respect to the Pareto front. In cases where datasets contain noise or parameters that cannot easily be expressed or evaluated mathematically, the presented measure provides a visual encoding of the environment of a Pareto front to enable an enhanced visual inspection.
Responsive Data Visualisation
(The Eurographics Association, 2017) Andrews, Keith; Smrdel, Aleš; Anna Puig Puig and Tobias Isenberg
In responsive web design, web pages are assembled from flexible components which adapt to the characteristics of the display device. For web pages to be truly responsive, any charts or visualisations embedded within them must themselves be responsive. This paper looks at the principles of responsive web design as applied to web-based information visualisations. Approaches are presented through which four commonly used visualisations (line chart, bar chart, parallel coordinates, and scatterplot) can be made responsive.
Visualization of Temporal Logic Specifications
(The Eurographics Association, 2017) Scott-Brown, James; Papachristodoulou, Antonis; Anna Puig Puig and Tobias Isenberg
The desired behaviour of a system can be formally specified using a temporal logic, and used to check whether a candidate design meets this specification, or to automatically design a system that does. Such techniques are in principle applicable to a wide range of types of systems, but their current extent of use does not fulfill their potential. One limitation has been the difficulty of writing and reading formal specifications. We present preliminary work on a visual method of viewing and editing specifications that is intended to address this challenge.
Memory Efficient Parallel Ray-casting Algorithm for Unstructured Grid Volume Rendering
(The Eurographics Association, 2017) Kim, Duksu; Anna Puig Puig and Tobias Isenberg
We propose a novel memory efficient parallel ray casting algorithm for unstructured grid. To reduce the high memory consumption of a previous work (i.e. Bunyk), we use a small size of local buffer for each thread to keep view dependent information for most recently visited faces. To improve the utilization efficiency of a local buffer, we propose an index-based hash function and a novel group traversal scheme. With our method, a small size buffer achieves a high hit ratio (i.e. utilization efficiency). As a result, we achieved a compatible performance with Bunyk while using less than 1% of memory space for view dependent face information. Also, our method shows even better performance than Bunyk for a large dataset since the buffer size is small enough to utilize CPU caches and our traversal scheme maximally takes advantage of the early ray termination optimization.
MDS-based Visual Survey of Biological Data Visualization Techniques
(The Eurographics Association, 2017) Kerren, Andreas; Kucher, Kostiantyn; Li, Yuan-Fang; Schreiber, Falk; Anna Puig Puig and Tobias Isenberg
Data visualization is of increasing importance in the Biosciences. During the past 15 years, a great number of novel methods and tools for biological data visualization have been developed and published in various journals and conference proceedings. As a consequence, keeping an overview of state-of-the-art visualization research has become increasingly challenging for both biology researchers as well as visualization researchers. To address this challenge, we have reviewed visualization research for the Biosciences and created an interactive web-based visualization tool, the BioVis Explorer. BioVis Explorer allows the exploration of published visualization methods in interactive and intuitive ways, including faceted browsing and associations with related methods.
An Interactive Visual Representation to Explore Association with Hierarchical Social Circles
(The Eurographics Association, 2017) Humayoun, Shah Rukh; Ali, Syed Hammad; AlTarawneh, Ragaad; Ebert, Achim; Anna Puig Puig and Tobias Isenberg
Showing the relations between the contacts of an ego network, a subset of a large social network, and these contacts' associations to different social circles enables us exploring inside behavior of the underlying ego network. Normally, these social circles contain multiple hierarchies in them and many times the social circles at the second or lower level in the hierarchy are non-mutually exclusive. In this work, we propose an intuitive design solution to visualize an ego network with associated social circles, where the inside Chord diagram represents the contacts and their relations in an ego network while the outside arcs represent the associated social circles, keeping their hierarchies and the non-mutually exclusive property. Our HiSoC-Vis tool provides a number of interaction and filtering options to make the resulting visualization more intuitive and customizable.

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