Computer Graphics & Visual Computing (CGVC) 2015

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https://diglib.eg.org/handle/10.2312/13226

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Browsing Computer Graphics & Visual Computing (CGVC) 2015 by Title

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    Explaining Neighborhood Preservation for Multidimensional Projections
    (The Eurographics Association, 2015) Martins, Rafael Messias; Minghim, Rosane; Telea, Alexandru C.; Rita Borgo and Cagatay Turkay
    Dimensionality reduction techniques are the tools of choice for exploring high-dimensional datasets by means of low-dimensional projections. However, even state-of-the-art projection methods fail, up to various degrees, in perfectly preserving the structure of the data, expressed in terms of inter-point distances and point neighborhoods. To support better interpretation of a projection, we propose several metrics for quantifying errors related to neighborhood preservation. Next, we propose a number of visualizations that allow users to explore and explain the quality of neighborhood preservation at different scales, captured by the aforementioned error metrics.We demonstrate our exploratory views on three real-world datasets and two state-of-the-art multidimensional projection techniques.
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    Extending the Scaffold Hunter Visualization Toolkit with Interactive Heatmaps
    (The Eurographics Association, 2015) Sturm, Werner; Schäfer, Till; Schreck, Tobias; Holzinger, Andreas; Ullrich, Torsten; Rita Borgo and Cagatay Turkay
    In many application areas, large amounts of data arise, which are often hard to interpret or make use of by humans. Interactive visualization can help to overview and explore large amounts of data. An example is in the life sciences, where databases of chemical compounds need to be analyzed in terms of similarities of molecular properties. Scientists then need to explore this data in an efficient way. The Scaffold Hunter framework is an Open Source software system for interactive visualization of highdimensional data. In this paper, we present an extension of Scaffold Hunter with an interactive heatmap, which ties in tightly with a dendrogram visualization. We added specific interaction modalities and views tailored to the analysis of chemical compounds. Zooming capabilities allow to start from an overview of the data (showing all data elements at once) down to a detail-on-demand view which includes chemical structural views of molecules. We show how the interactive heatmap with clustered rows and columns can bring new insights into the data regarding various properties. The implementation is made available for researchers and practitioners to use.
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    Frontmatter: Computer Graphics and Visual Computing (CGVC)
    (The Eurographics Association, 2015) Borgo, Rita; Turkay, Cagatay; Rita Borgo and Cagatay Turkay
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    GKS-94 to SVG: Some Reflections on the Evolution of Standards for 2D Graphics
    (The Eurographics Association, 2015) Duce, David A.; Hopgood, F.R.A.; Rita Borgo and Cagatay Turkay
    Activities to define international standards for computer graphics, in particular through ISO/IEC, started in the 1970s. The advent of the World Wide Web has brought new requirements and opportunities for standardization and now a variety of bodies including ISO/IEC and the World Wide Web Consortium (W3C) promulgate standards in this space. This paper takes a historical look at one of the early ISO/IEC standards for 2D graphics, the Graphical Kernel System (GKS) and compares key concepts and approaches in this standard (as revised in 1994) with concepts and approaches in the W3C Recommendation for Scalable Vector Graphics (SVG). The paper reflects on successes as well as lost opportunities.
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    Multivariate Hybrid Visualisation of Ornithological Sensor Data
    (The Eurographics Association, 2015) Roberts, Richard C.; Laramee, Robert S.; Jones, Mark W.; Rita Borgo and Cagatay Turkay
    To overcome the challenges of displaying multivariate sensor data, we propose a novel work-in-progress, hybrid, polar method of visualisation. Sensor data is collected by marine biologists in high volumes and using multiple sensors. Challenges arise when trying to unlock the marine wildlife behaviour from the vast amount of time series data collected. The proposed method filters uninteresting behaviour and isolates the features of interest within the set. Multi-layer polar plots are used to visualise local pressure, temperature, temporal behaviour and energy expenditure, all of which are given upper and lower plotting ranges to ensure no overlap. This results in a feature centred visualisation that focuses on the most important behaviour. The value in this method is that the visualisation can show many instances of the chosen activity. Each animal can be examined individually, or multiple animals and behaviours can be compared side-by-side for the first time. An interactive software system enables the user to navigate such that individual instances of the marine wildlife behaviour can be studied at high resolution or the user may choose an overview of every animal. This paper uses ornithological sensor data to demonstrate the proposed visualisation. Although it can be applied to other multivariate data sets that are linked with a temporal dimension.
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    Natural Phenomena as Metaphors for Visualization of Trend Data in Interactive Software Maps
    (The Eurographics Association, 2015) Würfel, Hannes; Trapp, Matthias; Limberger, Daniel; Döllner, Jürgen; Rita Borgo and Cagatay Turkay
    Software maps are a commonly used tool for code quality monitoring in software-development projects and decision making processes. While providing an important visualization technique for the hierarchical system structure of a single software revision, they lack capabilities with respect to the visualization of changes over multiple revisions. This paper presents a novel technique for visualizing the evolution of the software system structure based on software metric trends. These trend maps extend software maps by using real-time rendering techniques for natural phenomena yielding additional visual variables that can be effectively used for the communication of changes. Therefore, trend data is automatically computed by hierarchically aggregating software metrics. We demonstrate and discuss the presented technique using two real world data sets of complex software systems.
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    Tiled Projection Onto Deforming Screens
    (The Eurographics Association, 2015) Kim, Hyosun; Schinko, Christoph; Havemann, Sven; Redi, Ivan; Redi, Andrea; Fellner, Dieter W.; Rita Borgo and Cagatay Turkay
    For the next generation of visual installations it will not be sufficient to surround the visitor by stunning responsive audiovisual experiences - the next step is that space itself deforms in response to the user or user groups. Dynamic reconfigurable spaces are a new exciting possibility to influence the behaviour of groups and individuals; they may have the potential of stimulating various different social interactions and behaviours in a user-adapted fashion. However, some technical hurdles must be overcome. Projecting on larger surfaces, like a ceiling screen of 6 8 meters, is typically possible only with a tiled projection, i.e., with multiple projectors creating one large seamless image. This works well with a static ceiling; however, when the ceiling dynamically moves and deforms, the tiling becomes visible since the images no longer match. In this paper we present a method that can avoid such artifacts by dynamically adjusting the tiled projection to the deforming surface. Our method is surprisingly simple and efficient, and it does not require any image processing at runtime, nor any 3D reconstruction of the surface at any point.
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    Using Sketching to Control Heterogeneous Groups
    (The Eurographics Association, 2015) Allen, Thomas; Parvanov, Aleksandar; Knight, Sam; Maddock, Steve; Rita Borgo and Cagatay Turkay
    The basic methods of interaction in strategy games with regards to controlling groups of units has largely remained the same since the first strategy games were released. Although the control systems in games today are effective and intuitive, they are somewhat limiting for the user in terms of achieving more complex goals. Recently, there has been research into using sketch-based systems as an alternate means of controlling a crowd, granting a higher level of control to the user while maintaining an easy to use and intuitive interface. So far, however, this has only been implemented for homogeneous groups. This paper describes the implementation of a sketch-based crowd control system for strategy games, which allows the user to exert a greater level of control over their armies by giving them the ability to control heterogeneous groups by using sub-group sketching to distinguish formations and paths for groups and sub-groups to adhere to.
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    Visibility-Weighted Saliency for Volume Visualization
    (The Eurographics Association, 2015) Luo, Shengzhou; Dingliana, John; Rita Borgo and Cagatay Turkay
    Volume visualization has been widely used to depict complicated 3D structures in volume data sets. However, obtaining clear visualization of the features of interest in a volume is still a major challenge. The clarity of features depends on the transfer function, the viewpoint and the spatial distribution of features in the volume data set. In this paper, we propose visibility-weighted saliency as a measure of visual saliency of features in volume rendered images, in order to assist users in choosing suitable viewpoints and designing effective transfer functions to visualize the features of interest. Visibility-weighted saliency is based on a computational measure of perceptual importance of voxels and the visibility of features in volume rendered images. The effectiveness of this scheme is demonstrated by test results on two volume data sets.