Visualization is an effective means for exploring and analyzing complex data. Color coding is a fundamental technique for mapping data to visual representations. Although color coding is widely used in a large variety of visualizations, it is often provided in a limited way only or it is not used effectively. Therefore, we describe in this paper how appropriate (automatic) color coding can enhance the visual exploration of spatial-temporal data. We demonstrate our techniques with a system for visualizing human health data by means of choropleth maps. Furthermore, we focus on how to use color coding for facilitating comparison tasks in visualization.

Abstract — Systems biologists use interaction graphs to model the behavior of biological systems at the molecular level. In an iterative process, such biologists observe the reactions of living cells under various experimental conditions, view the results in the context of the interaction graph, and then propose changes to the graph model. These graphs serve as a form of dynamic knowledge representation of the biological system being studied and evolve as new insight is gained from the experimental data. While numerous graph layout and drawing packages are available, these tools did not fully meet the needs of our immunologist collaborators. In this paper, we describe the data information display needs of these immunologists and translate them into design decisions. These decisions led us to create Cerebral, a system that uses a biologically guided graph layout and incorporates experimental data directly into the graph display. Small multiple views of different experimental conditions and a data-driven parallel coordinates view enable correlations between experimental conditions to be analyzed at the same time that the data is viewed in the graph context. This combination of coordinated views allows the biologist to view the data from many different perspectives simultaneously. To illustrate the typical analysis tasks performed, we analyze two datasets using Cerebral. Based on feedback from our collaborators we conclude that Cerebral is a valuable tool for analyzing experimental data in the context of an interaction graph model. Index Terms—Graph layout, systems biology visualization, small multiples, design study. 1

We present a design technique for colors with the purpose of lowering the energy consumption of the display device. Our approach is based on a screen space variant energy model. The result of our design is a set of distinguishable iso-lightness colors guided by perceptual principles. We present two variations of our approach. One is based on a set of discrete user-named (categorical) colors, which are analyzed according to their energy consumption. The second is based on the constrained continuous optimization of color energy in the perceptually uniform CIELAB color space. We quantitatively compare our two approaches with a traditional choice of colors, demonstrating that we typically save approximately 40 percent of the energy. The color sets are applied to examples from the 2D visualization of nominal data and volume rendering of 3D scalar fields.

Abstract—Graphics artists commonly employ physically-based simulation for the generation of effects such as smoke, explosions, and similar phenomena. The task of finding the correct parameters for a desired result, however, is difficult and time-consuming as current tools provide little to no guidance. In this paper, we present a new approach for the visual exploration of such parameter spaces. Given a three-dimensional scene description, we utilize sampling and spatio-temporal clustering techniques to generate a concise overview of the achievable variations and their temporal evolution. Our visualization system then allows the user to explore the simulation space in a goal-oriented manner. Animation sequences with a set of desired characteristics can be composed using a novel search-by-example approach and interactive direct volume rendering is employed to provide instant visual feedback. A user study was performed to evaluate the applicability of our system in production use. Index Terms—Visual exploration, visual effects, clustering, time-dependent volume data. 1

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Abstract. Teaching InfoVis is a challenge because it is a new and growing field. This paper describes the results of a teaching survey based on the information given by the attendees of Dagstuhl Seminar 07221. It covers several aspects of offered InfoVis courses that range from different kinds of study materials to practical exercises. We have reproduced the discussion during the seminar and added our own experiences. We hope that this paper can serve as an interesting and helpful source for current and future InfoVis teachers. 1

Abstract—This design paper presents new guidance for creating map legends in a dynamic environment. Our contribution is a set of guidelines for legend design in a visualization context and a series of illustrative themes through which they may be expressed. These are demonstrated in an applications context through interactive software prototypes. The guidelines are derived from cartographic literature and in liaison with EDINA who provide digital mapping services for UK tertiary education. They enhance approaches to legend design that have evolved for static media with visualization by considering: selection, layout, symbols, position, dynamism and design and process. Broad visualization legend themes include: The Ground Truth Legend, The Legend as Statistical Graphic and The Map is the Legend. Together, these concepts enable us to augment legends with dynamic properties that address specific needs, rethink their nature and role and contribute to a wider re-evaluation of maps as artifacts of usage rather than statements of fact. EDINA has acquired funding to enhance their clients with visualization legends that use these concepts as a consequence of this work. The guidance applies to the design of a wide range of legends and keys used in cartography and information visualization. Index Terms—Cartography, design, Digimap service, legend, online web mapping, visualization. 1

Enabling teachers to explore grade patterns to identify individual needs and promote fairer student assessment

We present a design technique for colours that lower the energy consumption of the display device. Our approach relies on a screen space variant energy model. Guided by perceptual principles, we present three variations of our approach for finding low energy, distinguishable, iso-lightness colours. The first is based on a set of discrete user-named (categorical) colours, which are ordered according to energy consumption. The second optimizes for colours in the continuous CIELAB colour space. The third is hybrid, optimizing for colours in select CIELAB colour subspaces that are associated with colour names. We quantitatively compare our colours with a traditional choice of colours, demonstrating that approximately 45 percent of the display energy is saved. The colour sets are applied to 2D visualization of nominal data and volume rendering of 3D scalar fields. A new colour blending method for volume rendering which preserves hues further improves colour distinguishability.

and moments A manifesto for map studies