Welcome on the homepage of the chair "Computer Graphics Systems" of Prof. Jürgen Döllner and his team. We like to inform you about our teaching and ongoing research activities in the analysis, planning and construction of computer graphics and multimedia systems.
Improving Layout Quality by Mixing Treemap-Layouts Based on Data-Change Characteristics.Bethge, Joseph; Hahn, Sebastian; Döllner, Jürgen M. Hullin, Klein, R., Schultz, T., Yao, A. (reds.) (2017). (Vol. 2017)
This paper presents a hybrid treemap layout approach that optimizes layout-quality metrics by combining state-of-the-art treemap layout algorithms. It utilizes machine learning to predict those metrics based on data metrics describing the characteristics and changes of the dataset. For this, the proposed approach uses a neural network which is trained on artificially generated dataset,s containing a total of 15.8 million samples. The resulting model is integrated into an approach called Smart-Layouting. This approach is evaluated on real-world data from 100 publicly available software repositories. Compared to other state-of-the-art treemap algorithms it reaches an overall better result. Additionally, this approach can be customized by an end user’s needs. The customization allows for specifying weights for the importance of each layout-quality metric. The results indicate, that the algorithm is able to adapt successfully towards a given set of weights.
Hybrid-Treemap Layouting.Hahn, Sebastian; Döllner, Jürgen (2017).
Reducing Visual Complexity in Software Maps using Importance-based Aggregation of Nodes.Limberger, Daniel; Scheibel, Willy; Hahn, Sebastian; Döllner, Jürgen in Proceedings of the 8th International Conference on Information Visualization Theory and Applications (2017).
Space-restricted techniques for visualizing hierarchies generally achieve high scalability and readability (e.g., tree maps, bundle views, sunburst). However, the visualization layout directly depends on the hierarchy, that is, small changes to the hierarchy can cause wide-ranging changes to the layout. For this reason, it is difficult to use these techniques to compare similar variants of a hierarchy because users are confronted with layouts that do not expose the expected similarity. Voronoi treemaps appear to be promising candidates to overcome this limitation. However, existing Voronoi treemap algorithms do not provide deterministic layouts or assume a fixed hierarchy. In this paper we present an extended layout algorithm for Voronoi treemaps that provides a high degree of layout similiarity for varying hierarchies, such as software-system hierarchies. The implementation uses a deterministic initial-distribution approach that reduces the variation in node positioning even if changes in the underlying hierarchy data occur. Compared to existing layout algorithms, our algorithm achieves lower error rates with respect to node areas in the case of weighted Voronoi diagrams, which we show in a comparative study.
Interactive Rendering of Complex 3D-Treemaps.Trapp, Matthias; Hahn, Sebastian; Döllner, Jürgen S. Coquillart, Andujar, C., Laramee, R. S., Kerren, A., Braz, J. (reds.) (2013). 165-175.
3D-Treemaps are an important visualization technique for hierarchical views. In contrast to 2D-Treemaps, height can be used to map one additional attribute of the data items. Using the Treemap technique in combination with large datasets (more than 500k) a fast rendering and interaction techniques that are beyond collapsing/uncollapsing nodes is still one of the main challenges. This paper presents a novel rendering technique that enables the image synthesis of geometrical complex 3D-Treemaps in real-time. The fully hardware accelerated approach is based on shape generation using geometry shaders. This approach offers increased rendering performance and low update latency compared to existing techniques and through it enables new real-time interaction techniques to large datasets.
Lecture 3D Computergraphics I (tutor)
Seminar Methods and Techniques of Software Visualization (tutor)
Lecture 3D Computergraphics II (tutor)
Seminar Systems Engineering for Software Analytics (tutor)
Seminar Visual Software Analytics (tutor)
Lecture Einführung in die Programmiertechnik II (tutor)
Seminar Visualization for Interactive Software Analytics (tutor)
Bachelor's project Software Analytics and Visualization (co-supervisor)
Lecture 3D Computergraphics I (tutor)
Seminar Software Analytics (tutor)
Seminar Game Programming (tutor)
Lecture Geovisualization (tutor)
Seminar Softwarevisualisierungsverfahren (tutor)
Bachelor's project A Visualization Tool for Software Evolution (co-supervisor)
Lecture Visualization (tutor)
Seminar Softwareanalyseverfahren (tutor)
ThreadCity: Combined Visualization of Structure and Activity of Multi-threaded Software Systems - Nikolai Wuttke (finished)
Participant of ETH Winter School on Eye Tracking (January 2016)
Teaching-Team Member OpenHPI Course "Automated Visual Software Analytics" (March 2015)
SoftVis project in cooperation with the SAP Innovation Center, Potsdam (April 2012 - March 2016)