EuroVisShort

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3D Strokes on Visible Structures in Direct Volume Rendering
(The Eurographics Association, 2013) Wiebel, Alexander; Preis, Philipp; Vos, Frans M.; Hege, Hans-Christian; Mario Hlawitschka and Tino Weinkauf
In this paper we describe VisiTrace, a novel technique to draw 3D lines in direct volume rendered images. It allows to draw strokes in the 2D space of the screen to produce 3D lines that run on top or in the center of structures visible in the rendering. It is able to ignore structures that shortly occlude the structure that has been visible at the start of the stroke. For this purpose a shortest path algorithm finding the optimal curve in a specially designed graph is employed. We demonstrate the usefulness of the technique by applying it to image data from medicine and engineering, and show how it can be used to mark structures in the example data, and to automatically obtain good views toward these structures enabling faster navigation in the rendering.
Accelerated Volume Rendering with Volume Guided Neural Denoising
(The Eurographics Association, 2023) Jabbireddy, Susmija; Li, Shuo; Meng, Xiaoxu; Terrill, Judith E.; Varshney, Amitabh; Hoellt, Thomas; Aigner, Wolfgang; Wang, Bei
Monte Carlo path tracing techniques create stunning visualizations of volumetric data. However, a large number of computationally expensive light paths are required for each sample to produce a smooth and noise-free image, trading performance for quality. High-quality interactive volume rendering is valuable in various fields, especially education, communication, and clinical diagnosis. To accelerate the rendering process, we combine learning-based denoising techniques with direct volumetric rendering. Our approach uses additional volumetric features that improve the performance of the denoiser in the post-processing stage. We show that our method significantly improves the quality of Monte Carlo volume-rendered images for various datasets through qualitative and quantitative evaluation. Our results show that we can achieve volume rendering quality comparable to the state-of-the-art at a significantly faster rate using only one sample path per pixel.
Additional On-Demand Dimension for Data Visualization
(The Eurographics Association, 2017) Hube, Natalie; Müller, Mathias; Groh, Rainer; Barbora Kozlikova and Tobias Schreck and Thomas Wischgoll
In this paper, we present a concept to interactively extend an 2d visualization by an additional on-demand dimension. We use categorical data in a multidimensional information space applied in a travel search scenario. Parallel sets are used as the basis for the visualization concept, since this is particularly suitable for the visualization of categorical data. The on-demand dimension expands the vertical axis of a parallel coordinate graph into depth axis and is intended to increase comparability of path variables with respect to the number of elements belonging to the respective parameter axis instead of direct comparability of individual paths and keep relations between the parallel sets. The presented implementation suits as foundation for further studies about the usefulness of a dynamic, on demand extension a of 2d visualizations into spatial visualizations. Furthermore, we present some additional approaches about the usage of the increased visualization space.
Algorithmic Improvements on Hilbert and Moore Treemaps for Visualization of Large Tree-structured Datasets
(The Eurographics Association, 2021) Scheibel, Willy; Weyand, Christopher; Bethge, Joseph; Döllner, Jürgen; Agus, Marco and Garth, Christoph and Kerren, Andreas
Hilbert and Moore treemaps are based on the same named space-filling curves to lay out tree-structured data for visualization. One main component of them is a partitioning subroutine, whose algorithmic complexity poses problems when scaling to industry-sized datasets. Further, the subroutine allows for different optimization criteria that result in different layout decisions. This paper proposes conceptual and algorithmic improvements to this partitioning subroutine. Two measures for the quality of partitioning are proposed, resulting in the min-max and min-variance optimization tasks. For both tasks, linear-time algorithms are presented that find an optimal solution. The implementation variants are evaluated with respect to layout metrics and run-time performance against a previously available greedy approach. The results show significantly improved run time and no deterioration in layout metrics, suggesting effective use of Hilbert and Moore treemaps for datasets with millions of nodes.
Ambient Grids: Maintain Context-Awareness via Aggregated Off-Screen Visualization
(The Eurographics Association, 2015) Jäckle, Dominik; Stoffel, Florian; Kwon, Bum Chul; Sacha, Dominik; Stoffel, Andreas; Keim, Daniel A.; E. Bertini and J. Kennedy and E. Puppo
When exploring large spatial datasets, zooming and panning interactions often lead to the loss of contextual overview. Existing overview-plus-detail approaches allow users to view context while inspecting details, but they often suffer from distortion or overplotting. In this paper, we present an off-screen visualization method called Ambient Grids that strikes the balance between overview and details by preserving the contextual information as color grids within a designated space around the focal area. In addition, we describe methods to generate Ambient Grids for point data using data aggregation and projection. In a use case, we show the usefulness of our technique in exploring the VAST Challenge 2011 microblog dataset.
Analysis of Error in Interpolation-Based Pathline Tracing
(The Eurographics Association, 2016) Chandler, Jennifer; Bujack, Roxana; Joy, Kenneth I.; Enrico Bertini and Niklas Elmqvist and Thomas Wischgoll
Chandler et al. [COJ15] presented interpolation-based pathline tracing as an alternative to numerical integration for advecting tracers in particle-based flow fields and showed that their method has lower error than a numerical integration-based method for particle tracing. We seek to understand the sources of the error in interpolation-based pathline tracing. We present a formal analysis of the theoretical bound on the error when advecting pathlines using this method. We characterize the error experimentally using characteristics of the flow field such as neighborhood change, flow divergence, and trajectory length. Understanding the sources of error in an advection method is important to know where there may be uncertainty in the resulting analysis. We find that for interpolation-based pathline tracing the error is closely related to the divergence in the flow field.
Analytic Behavior and Trust Building in Visual Analytics
(The Eurographics Association, 2016) Sacha, Dominik; Boesecke, Ina; Fuchs, Johannes; Keim, Daniel A.; Enrico Bertini and Niklas Elmqvist and Thomas Wischgoll
Visual Analytics (VA) is a collaborative process between human and computer, where analysts are performing numerous interactions and reasoning activities. This paper presents our current progress in developing a note taking environment (NTE) that can be plugged to any VA system. The NTE supports the analysis process on the one hand, and captures user interactions on the other hand. Our aim is to integrate human lower- (exploration) with higher- (verification) level analytic processes and to investigate those together related to further human factors, such as trust building. We conducted a user study to collect and investigate analytic provenance data. Our early results reveal that analysis strategies and trust building are very individual. However, we were able to identify significant correlations between trust levels and interactions of particular participants.
Analytic Ray Splitting for Controlled Precision DVR
(The Eurographics Association, 2021) Weiss, Sebastian; Westermann, Rüdiger; Agus, Marco and Garth, Christoph and Kerren, Andreas
For direct volume rendering of post-classified data, we propose an algorithm that analytically splits a ray through a cubical cell at the control points of a piecewise-polynomial transfer function. This splitting generates segments over which the variation of the optical properties is described by piecewise cubic functions. This allows using numerical quadrature rules with controlled precision to obtain an approximation with prescribed error bounds. The proposed splitting scheme can be used to find all piecewise linear or monotonic segments along a ray, and it can thus be used to improve the accuracy of direct volume rendering, scale-invariant volume rendering, and multi-isosurface rendering.
Analyzing the Evolution of the Internet
(The Eurographics Association, 2015) Johnson, Thienne; Acedo, Carlos; Kobourov, Stephen; Nusrat, Sabrina; E. Bertini and J. Kennedy and E. Puppo
Existing representations of the Internet do not provide information on why countries have a bigger Internet presence (e.g., Internet Service Providers) than others. In this paper we evaluate four geo-economic parameters (area, population, GDP and GDP per capita), looking for clues of why some areas or countries have developed earlier/ later, faster/slower than others. We use correlation studies to analyze which geo-economic variable leads to bigger development in the Internet infrastructure per continent, and cartograms to represent the growth of the Internet infrastructure around the world, in a sequence of 24 years. These representations make it possible to find interesting patterns and identify outliers.
Application-oriented Analysis of Material Interface Reconstruction Algorithms in Time-varying Bijel Simulations
(The Eurographics Association, 2022) Bao, Xueyi; Karthikeyan, Nikhil; Schiller, Ulf D.; Iuricich, Federico; Agus, Marco; Aigner, Wolfgang; Hoellt, Thomas
Multimaterial interface reconstruction has been investigated over the years both from visualization and analytical point of view using different metrics. When focusing on visualization, interface continuity and smoothness are used to quantify interface quality. When the end goal is interface analysis, metrics closer to the physical properties of the material are preferred (e.g., curvature, tortuosity). In this paper, we re-evaluate three Multimaterial Interface Reconstruction (MIR) algorithms, already integrated in established visualization frameworks, under the lens of application-oriented metrics. Specifically, we analyze interface curvature, particle-interface distance, and medial axis-interface distance in a time-varying bijel simulation. Our analysis shows that the interface presenting the best visual qualities is not always the most useful for domain scientists when evaluating the material properties.
arcs.fm - A Backdrop Visualization for Music Talk
(The Eurographics Association, 2012) Baur, Dominikus; Butz, Andreas; Carpendale, Sheelagh; Miriah Meyer and Tino Weinkaufs
Visualizations usually completely capture our attention or disappear into the ambient background. In this paper we explore a middle ground, with visualizations that are not constantly in the center of attention and support a main conversational task without distracting from it. Such backdrop visualizations work for look-up and analytical tasks without getting in the way of the conversation, but can also be used actively. To illustrate this concept we describe arcs.fm, a case study for music talk, as an exemplary backdrop visualization. Music fulfills an important function for identity construction: we define ourselves by what music we listen to and we like to compare our musical taste with friends and family. The shift towards digital music allows us to meticulously keep track of all songs we have listened to and to have access to this data to augment our memories. Here we explore integrating visualizations of automatically collected listening histories with the explanations and discussion that develop in personal music talk. arcs.fm is a visualization system that supports this music talk by comparing two listening histories visually. arcs.fm stays in the background while enabling look-up and enriching peoples' conversation when needed.
An Argument Structure for Data Stories
(The Eurographics Association, 2017) Kosara, Robert; Barbora Kozlikova and Tobias Schreck and Thomas Wischgoll
Many data stories in journalism do not have a story arc, but rather present facts without much structure. This mirrors the popular inverted pyramid style of writing that presents the most important information up front, to be followed by evidence. We have found a subset of stories that follow a more structured approach, however. These stories begin with a claim or question, but do not immediately present that as the conclusion. Instead, they then present pieces of evidence that are only tied together, and back to the initial claim, at the end. In this paper, we formalize and discuss this structure, and present a few examples. We believe that this is a viable and practical model for data stories more generally, and certainly a stronger arc than most existing stories today.
ARGUS: Interactive Visual Analytics Framework for the Discovery of Disruptions in Bio-Behavioral Rhythms
(The Eurographics Association, 2020) Mansoor, Hamid; Gerych, Walter; Buquicchio, Luke; Alajaji, Abdulaziz; Chandrasekaran, Kavin; Agu, Emmanuel; Rundensteiner, Elke; Kerren, Andreas and Garth, Christoph and Marai, G. Elisabeta
Human Bio-Behavioral Rhythms (HBRs) such as sleep-wake cycles and their regularity have important health ramifications. Smartphones can sense HBRs by gathering and analyzing data from built-in sensors, which provide behavioral clues. The multichannel nature (multiple sensor streams) of such data makes it challenging to pin-point the causes of disruptions in HBRs. Prior work has utilized machine learning for HBR classification but has not facilitated deeper understanding or reasoning about the potential disruption causes. In this paper, we propose ARGUS, an interactive visual analytics framework to discover and understand HBR disruptions and causes. The foundation of ARGUS is a Rhythm Deviation Score (RDS) that extracts a user's underlying 24-hour rhythm from their smartphone sensor data and quantifies its irregularity. ARGUS then visualizes the RDS using a glyph to easily recognize disruptions in HBRs, along with multiple linked panes that overlay sensor information and user-provided or smartphone-inferred ground truth as supporting context. This framework visually captures a comprehensive picture of HBRs and their disruptions. ARGUS was designed by an expert lead goal-and-task analysis. To demonstrate its generalizability, two different smartphone-sensed datasets were visualized using ARGUS in conjunction with expert feedback.
ARrow: A Real-Time AR Rowing Coach
(The Eurographics Association, 2023) Iannucci, Elena; Chen, Zhutian; Armeni, Iro; Pollefeys, Marc; Pfister, Hanspeter; Beyer, Johanna; Hoellt, Thomas; Aigner, Wolfgang; Wang, Bei
Rowing requires physical strength and endurance in athletes as well as a precise rowing technique. The ideal rowing stroke is based on biomechanical principles and typically takes years to master. Except for time-consuming video analysis after practice, coaches currently have no means to quantitatively analyze a rower's stroke sequence and body movement. We propose ARrow, an AR application for coaches and athletes that provides real-time and situated feedback on a rower's body position and stroke. We use computer vision techniques to extract the rower's 3D skeleton and to detect the rower's stroke cycle. ARrow provides visual feedback on three levels: Tracking of basic performance metrics over time, visual feedback and guidance on a rower's stroke sequence, and a rowing ghost view that helps synchronize the body movement of two rowers. We developed ARrow in close colaboration with international rowing coaches and demonstrate its usefulness in a user study with athletes and coaches.
Ask and You Shall Receive (a Graph Drawing): Testing ChatGPT's Potential to Apply Graph Layout Algorithms
(The Eurographics Association, 2023) Bartolomeo, Sara Di; Severi, Giorgio; Schetinger, Victor; Dunne, Cody; Hoellt, Thomas; Aigner, Wolfgang; Wang, Bei
Large language models (LLMs) have recently taken the world by storm. They can generate coherent text, hold meaningful conversations, and be taught concepts and basic sets of instructions-such as the steps of an algorithm. In this context, we are interested in exploring the application of LLMs to graph drawing algorithms by performing experiments on ChatGPT, one of the most recent cutting-edge LLMs made available to the public. These algorithms are used to create readable graph visualizations. The probabilistic nature of LLMs presents challenges to implementing algorithms correctly, but we believe that LLMs' ability to learn from vast amounts of data and apply complex operations may lead to interesting graph drawing results. For example, we could enable users with limited coding backgrounds to use simple natural language to create effective graph visualizations. Natural language specification would make data visualization more accessible and user-friendly for a wider range of users. Exploring LLMs' capabilities for graph drawing can also help us better understand how to formulate complex algorithms for LLMs; a type of knowledge that could transfer to other areas of computer science. Overall, our goal is to shed light on the exciting possibilities of using LLMs for graph drawing-using the Sugiyama algorithm as a sample case-while providing a balanced assessment of the challenges and opportunities they present. A free copy of this paper with all supplemental materials to reproduce our results is available on osf.io .
Augmented Intelligence with Interactive Voronoi Treemap for Scalable Grouping: a Usage Scenario with Wearable Data
(The Eurographics Association, 2022) Abuthawabeh, Ala; Baggag, Abdelkader; Aupetit, Michael; Agus, Marco; Aigner, Wolfgang; Hoellt, Thomas
Interactive Voronoi Treemaps have been proposed to support arrangement and grouping tasks of data with snippet image representations. They rely on time-consuming manual actions to group data and cannot display more than a hundred images without occlusion. We propose visualizations designed to manage images visibility, evaluate group homogeneity, and shorten grouping task completion time while keeping control. It is supported by an automatic classifier forming an augmented intelligence system to tackle arrangement and grouping tasks at scale. We propose the usage scenario of a clinician using Interactive Voronoi Treemaps to group wearable data based on sleep visual patterns.
Authoring Combined Textual and Visual Descriptions of Graph Data
(The Eurographics Association, 2019) Latif, Shahid; Su, Kaidie; Beck, Fabian; Johansson, Jimmy and Sadlo, Filip and Marai, G. Elisabeta
The interactive linking of text and visualizations supports easy and guided exploration of information and results in a coherent document. Authoring such documents for the web requires writing custom HTML and JavaScript. Existing research aims at reducing the effort by providing a declarative syntax. However, these approaches either do not support the interactive linking of text and visualizations or require advance programming skills to establish this linking. Targeting a specific type of data i.e., graph data, we introduce an approach that uses a declarative syntax to produce interactive documents and requires little to no programming. Based on the user specifications in an HTML file, the system queries the database to retrieve subgraphs and link them to the relevant text fragments. The resulting document consists of a node-link diagram and text; the two representations are closely linked via interactions and word-sized graphics, and provide an active reading experience.
Automatic Geometric Calibration of Projector-based Light Field Displays
(The Eurographics Association, 2013) Agus, Marco; Gobbetti, Enrico; Jaspe, Alberto; Pintore, Giovanni; Pintus, Ruggero; Mario Hlawitschka and Tino Weinkauf
We present a novel calibration method for continuous multiview (light field) projection-based displays using a single uncalibrated camera and four fiducial markers. Calibration starts from a simple parametric description of the display layout. First, individual projectors are calibrated through parametric optimization of an idealized pin- hole model. Then, the overall display and projector parameterization is globally optimized. Finally, independently for each projector, remaining errors are corrected through a rational 2D warping function. The final parame- ters are available to rendering engines to quickly compute forward and backward projections. The technique is demonstrated in the calibration of a large-scale horizontal-parallax-only 35MPixels light field display.
B:3D - Visualize Land-use Plans Interactively
(The Eurographics Association, 2013) Langbein, Max; Scheler, Inga; Ebert, Achim; Hagen, Hans; Mario Hlawitschka and Tino Weinkauf
In Europe, urban land-use plans only give a very abstract representation of possible building forms. Combined with a written statement describing all constraints, the so-called building code, architects have to start planning. This can create many problems by violating the building codes. To overcome these problems we developed a system visualizing building code violations in real-time and giving a spatial impression of the planned area by an additional output on 3D printers and 3D displays.
Bilateral Depth Filtering for Enhanced Vessel Reformation
(The Eurographics Association, 2014) Kretschmer, Jan; Preim, Bernhard; Stamminger, Marc; N. Elmqvist and M. Hlawitschka and J. Kennedy
Curved Planar Reformation is a powerful visualization technique for the diagnosis of vascular diseases. It allowsan accurate centerline-driven investigation of vessel lumen while providing valuable anatomical context.Extended methods like Multipath Curved Planar Reformation, Centerline Reformation or Curved Surface Reformationprovide additional flexibility by condensing entire vascular systems into rotatable views. Unfortunately, allthese methods produce depth discontinuities because they operate in a projective fashion. While large discontinuitiesprovide valuable hints about distinct anatomical contexts, small discontinuities, which frequently arise, havedistracting effects on the visualization result and do not contribute significant information. In this paper we presenta bilateral filtering technique which allows to selectively remove depth discontinuities without affecting discontinuitiesthat carry information. The presented approach significantly improves the quality of vessel reformations,can be applied at interactive frame rates and is orthogonal to existing methods.

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