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Item On Establishing Visualization Requirements: A Case Study in Product Costing(The Eurographics Association, 2017) Vosough, Zana; Groh, Rainer; Schulz, Hans-Jörg; Barbora Kozlikova and Tobias Schreck and Thomas WischgollThe process of identifying visualization requirements is an important part of every visualization researcher's and practitioner's job. Nevertheless, the scientific literature is rather sparse on this topic, usually resorting to some form of user-centered design that is rarely further detailed. In this paper, we give an account of our procedure, our results, our problems and solutions for gathering visualization requirements in an ongoing business project to introduce visualization to the field of product costing. By providing insight in our experiences and extracting general points of advice from them, we aim to give some practical guidance for establishing requirements in real-world visualization projects.Item Transient Visual Analytics(The Eurographics Association, 2024) Schulz, Hans-Jörg; Weaver, Chris; El-Assady, Mennatallah; Schulz, Hans-JörgVisual Analytics often utilizes progression as a means to overcome the challenges presented by large amounts of data or extensive computations. In Progressive Visual Analytics (PVA), data gets chunked into smaller subsets, which are then processed independently, and subsequently added to a visualization that completes over time. We introduce Transient Visual Analytics (TVA), which complements this incremental addition of data with progressive removal of data as it becomes outdated, starts to clutter the visualization, and generally distracts from the data that is currently relevant to visual analysis. Through combinations of various progressive addition and removal strategies, and supported by suitable analogies for the analyst and the software engineer, TVA captures a variety of visual analysis scenarios and approaches that are not well captured by PVA alone.Item ReVize: A Library for Visualization Toolchaining with Vega-Lite(The Eurographics Association, 2019) Hogräfer, Marius; Schulz, Hans-Jörg; Agus, Marco and Corsini, Massimiliano and Pintus, RuggeroThe field of tools for data visualization has been growing in recent years, with each tool contributing new ways to create and work with visualizations, and each offering a specialized set of features, interaction metaphors and user interfaces. This means on one hand that users have a wide choice in visualization tools. On the other hand, though, this choice might also lock-in the user: Once made, it becomes difficult and sometimes even impossible to switch to another tool - e.g., to further refine a visualization made in one tool inside another. In turn, users are forced to work around any shortcomings of the chosen tool, as switching to another tool is even more cumbersome. In this paper, we introduce ReVize, an open-source library for visualization toolchaining. ReVize makes use of Vega-Lite as a common exchange format to be able to add toolchain support to web-based tools. In contrast to existing approaches, this solution to visualization toolchaining allows for authoring a visualization with multiple tools in a back-and-forth fashion, without a preset order in which tools are to be used. We demonstrate ReVize by adding toolchain support to three existing tools - KNIME, ColorBrewer, and VisFlow - for using them in concert to author visualizations.Item Highways and Tunnels: Force Feedback Guidance for Visualisations(The Eurographics Association, 2024) Alrøe, Sarah Fjelsted; Hoggan, Eve; Schulz, Hans-Jörg; Tominski, Christian; Waldner, Manuela; Wang, BeiNon-visual methods of user guidance in visualisations are still relatively underexplored. This paper aims to address this, by establishing a foundation for appropriately using haptic force feedback in a pointing device to provide guidance, with a focus on pulling and constraining. To explore these guidance methods, a force feedback enabled mouse was constructed, along with a force feedback enabled data visualisation. A user study was conducted, subjecting the participants to different degrees of pulling and constraining guidance, helping them solve navigation tasks. The study found significant quantitative and qualitative changes in behaviour and experience across conditions. We conclude that these two modes of feedback can be used for directing and prescribing guidance situations, provided they are used with restraint.Item A Pipeline for Tailored Sampling for Progressive Visual Analytics(The Eurographics Association, 2022) Hogräfer, Marius; Burkhardt, Jakob; Schulz, Hans-Jörg; Bernard, Jürgen; Angelini, MarcoProgressive Visual Analytics enables analysts to interactively work with partial results from long-running computations early on instead of forcing them to wait. For very large datasets, the first step is to divide that input data into smaller chunks using sampling, which are then passed down the progressive analysis pipeline all the way to their progressive visualization in the end. The quality of the partial results produced by the progression heavily depends on the quality of these chunks, that is, chunks need to be representative of the dataset. Whether or not a sampling approach produces representative chunks does however depend on the particular analysis scenario. This stands in contrast to the common use of random sampling as a ''one-size-fits-most'' approach in PVA. In this paper, we propose a sampling pipeline and its open source implementation which can be used to tailor the used sampling method for an analysis scenario at hand. This pipeline consists of three configurable steps - linearization, subdivision, and selection - and for each, we propose exemplar operators. We then demonstrate its utility by providing tailored samplings for three distinct scenarios.Item EuroVis 2024 Panels and Tutorials: Frontmatter(The Eurographics Association, 2024) Schulz, Hans-Jörg; Isenberg, Tobias; Schulz, Hans-Jörg; Isenberg, TobiasItem Sketchy Rendering to Aid the Recollection of Regular Visualizations(The Eurographics Association, 2020) Larsen, Michael Reidun Engelbrecht; Han, Wenkai; Schulz, Hans-Jörg; Kerren, Andreas and Garth, Christoph and Marai, G. ElisabetaSome visualizations have a more regular visual appearance than others. For example, while stream graphs or force-directed network layouts feature a unique, almost organic 'look and feel', matrices or unit treemaps can become rather bland, grid-like visualizations in which one data item is hard to tell apart from the next. In this paper, we investigate the use of sketchy rendering for such grid-like visualizations to give them a slightly more unique 'look and feel' themselves. We evaluate our approach in a lab study (N = 16) where participants were asked to re-find a given grid cell in regular and sketchy grids. We find that users who make conscious use of the sketchy features can benefit from certain forms of sketchy rendering in terms of task completion times.Item VMV 2019: Frontmatter(Eurographics Association, 2019) Schulz, Hans-Jörg; Teschner, Matthias; Wimmer, Michael; Schulz, Hans-Jörg and Teschner, Matthias and Wimmer, MichaelItem Progressive Parameter Space Visualization for Task-Driven SAX Configuration(The Eurographics Association, 2020) Loeschcke, Sebastian; Hogräfer, Marius; Schulz, Hans-Jörg; Turkay, Cagatay and Vrotsou, KaterinaAs time series datasets are growing in size, data reduction approaches like PAA and SAX are used to keep them storable and analyzable. Yet, finding the right trade-off between data reduction and remaining utility of the data is a challenging problem. So far, it is either done in a user-driven way and offloaded to the analyst, or it is determined in a purely data-driven, automated way. None of these approaches take the analytic task to be performed on the reduced data into account. Hence, we propose a task-driven parametrization of PAA and SAX through a parameter space visualization that shows the difference of progressively running a given analytic computation on the original and on the reduced data for a representative set of data samples. We illustrate our approach in the context of climate analysis on weather data and exoplanet detection on light curve data.Item LaNe Plot: A Visual Fingerprinting Technique for Sequential Data(The Eurographics Association, 2024) Rathish, Harith; Picón, Ginés Carreto; Schulz, Hans-Jörg; Kucher, Kostiantyn; Diehl, Alexandra; Gillmann, ChristinaVisual summaries of sequential data are often used to identify common trends at a glance. In this poster, we propose a visualization technique to fingerprint sequential data by showing the difference between contiguous data points. For each data point in the sequence, we visualize the difference between itself and the last data point as well as the next data point. As an application, we visualized the revision histories of Wikipedia articles to demonstrate the exploratory value of this technique.