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Item A Survey on Video-based Graphics and Video Visualization(The Eurographics Association, 2011) Borgo, Rita; Chen, Min; Daubney, Ben; Grundy, Edward; Heidemann, Gunther; Höferlin, Benjamin; Höferlin, Markus; Jänicke, Heike; Weiskopf, Daniel; Xie, Xianghua; N. John and B. WyvillIn recent years, a collection of new techniques which deal with video as input data, emerged in computer graphics and visualization. In this survey, we report the state of the art in video-based graphics and video visualization. We provide a comprehensive review of techniques for making photo-realistic or artistic computer-generated imagery from videos, as well as methods for creating summary and/or abstract visual representations to reveal important features and events in videos. We propose a new taxonomy to categorize the concepts and techniques in this newlyemerged body of knowledge. To support this review, we also give a concise overview of the major advances in automated video analysis, as some techniques in this field (e.g., feature extraction, detection, tracking and so on) have been featured in video-based modeling and rendering pipelines for graphics and visualization.Item Energy Aware Color Sets(The Eurographics Association and Blackwell Publishing Ltd, 2009) Chuang, Johnson; Weiskopf, Daniel; Moeller, TorstenWe 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.Item Particle Level Set Advection for the Interactive Visualization of Unsteady 3D Flow(The Eurographics Association and Blackwell Publishing Ltd., 2008) Cuntz, Nicolas; Kolb, Andreas; Strzodka, Robert; Weiskopf, Daniel; A. Vilanova, A. Telea, G. Scheuermann, and T. MoellerTypically, flow volumes are visualized by defining their boundary as iso-surface of a level set function. Grid-based level sets offer a good global representation but suffer from numerical diffusion of surface detail, whereas particlebased methods preserve details more accurately but introduce the problem of unequal global representation. The particle level set (PLS) method combines the advantages of both approaches by interchanging the information between the grid and the particles. Our work demonstrates that the PLS technique can be adapted to volumetric dye advection via streak volumes, and to the visualization by time surfaces and path volumes. We achieve this with a modified and extended PLS, including a model for dye injection. A new algorithmic interpretation of PLS is introduced to exploit the efficiency of the GPU, leading to interactive visualization. Finally, we demonstrate the high quality and usefulness of PLS flow visualization by providing quantitative results on volume preservation and by discussing typical applications of 3D flow visualization.Item Visualizing a Sequence of a Thousand Graphs (or Even More)(The Eurographics Association and John Wiley & Sons Ltd., 2017) Burch, Michael; Hlawatsch, Marcel; Weiskopf, Daniel; Heer, Jeffrey and Ropinski, Timo and van Wijk, JarkeThe visualization of dynamic graphs demands visually encoding at least three major data dimensions: vertices, edges, and time steps. Many of the state-of-the-art techniques can show an overview of vertices and edges but lack a data-scalable visual representation of the time aspect. In this paper, we address the problem of displaying dynamic graphs with a thousand or more time steps. Our proposed interleaved parallel edge splatting technique uses a time-to-space mapping and shows the complete dynamic graph in a static visualization. It provides an overview of all data dimensions, allowing for visually detecting timevarying data patterns; hence, it serves as a starting point for further data exploration. By applying clustering and ordering techniques on the vertices, edge splatting on the links, and a dense time-to-space mapping, our approach becomes visually scalable in all three dynamic graph data dimensions. We illustrate the usefulness of our technique by applying it to call graphs and US domestic flight data with several hundred vertices, several thousand edges, and more than a thousand time steps.Item Progressive Splatting of Continuous Scatterplots and Parallel Coordinates(The Eurographics Association and Blackwell Publishing Ltd., 2011) Heinrich, Julian; Bachthaler, S.; Weiskopf, Daniel; H. Hauser, H. Pfister, and J. J. van WijkContinuous scatterplots and parallel coordinates are used to visualize multivariate data defined on a continuous domain. With the existing techniques, rendering such plots becomes prohibitively slow, especially for large scientific datasets. This paper presents a scalable and progressive rendering algorithm for continuous data plots that allows exploratory analysis of large datasets at interactive framerates. The algorithm employs splatting to produce a series of plots that are combined using alpha blending to achieve a progressively improving image. For each individual frame, splats are obtained by transforming Gaussian density kernels from the 3-D domain of the input dataset to the respective data domain. A closed-form analytic description of the resulting splat footprints is derived to allow pre-computation of splat textures for efficient GPU rendering. The plotting method is versatile because it supports arbitrary reconstruction or interpolation schemes for the input data and the splatting technique is scalable because it chooses splat samples independently from the size of the input dataset. Finally, the effectiveness of the method is compared to existing techniques regarding rendering performance and quality.Item Visualization Curriculum Panel - or The Changes We Have Made to Our Visualization Courses Over the Last 10 Years(The Eurographics Association, 2012) Domik, Gitta; Ebert, David; Kohlhammer, Jörn; Rushmeier, Holly; Santos, Beatriz Sousa; Weiskopf, Daniel; Giovanni Gallo and Beatriz Sousa SantosThe last ten years have seen profound changes in algorithms, techniques, and applications of visualization. Additionally, we see changes in the sophistication and expectations of our students in visualization courses. This panel will reflect changes in teaching visualization courses through the personal reflections of renowned researchers and educators on their alterations on course content over the past 10 yearsItem A Matrix-Based Visual Comparison of Time Series Sports Data(The Eurographics Association, 2016) Beck, Fabian; Burch, Michael; Weiskopf, Daniel; Matthias Hullin and Marc Stamminger and Tino WeinkaufIn sports, large amounts of data are measured and stored with the help of modern sensors and electronic devices. In particular, for endurance sports events, time-varying data are recorded and can be used to analyze the athletes' performance. Finding patterns and issues can help better understand results in sports competitions, which is of interest for the athletes, sports managers, and trainers alike. In this paper, we introduce a matrix-based approach to visually compare similar and dissimilar periods in performances of athletes. We differentiate the performances and visually encode these differences as color-coded matrix cells. The strengths of our approach are illustrated in a case study investigating the performances of two riders in the prologue of Tour de France 2012.Item Evaluation of Visualizations for Interface Analysis of SPH(The Eurographics Association, 2014) Krone, Michael; Huber, Markus; Scharnowski, Katrin; Hirschler, Manuel; Kauker, Daniel; Reina, Guido; Nieken, Ulrich; Weiskopf, Daniel; Ertl, Thomas; N. Elmqvist and M. Hlawitschka and J. KennedyWe present a GPU-accelerated visualization application that employs methods from computer graphics and visualizationto analyze SPH simulations from the field of material science. To this end, we extract the isosurfacethat separates the stable phases in a fluid mixture via the kernel function that was used by the simulation. Ourapplication enables the analysis of the separation process using interactive 3D renderings of the data and an additionalline chart that shows the computed surface area over time. This also allows us to validate the correctnessof the simulation method, since the surface area can be compared to the power law that describes the change inarea over time. Furthermore, we compare the isosurface that is based on the simulation kernel with an establishedmethod to extract smooth high-quality SPH surfaces. The comparison focuses on demonstrating the applicabilityfor data analysis in the context of material science, which is based on the resulting surface area and how wellthe two phases are separated with respect to the original particles. The evaluation was carried out together withexperts in material science.Item Real-Time Advection and Volumetric Illumination for the Visualization of 3D Unsteady Flow(The Eurographics Association, 2005) Weiskopf, Daniel; Schafhitzel, Tobias; Ertl, Thomas; Ken Brodlie and David Duke and Ken JoyThis paper presents an interactive technique for the dense texture-based visualization of unsteady 3D flow, taking into account issues of computational efficiency and visual perception. High efficiency is achieved by a novel 3D GPU-based texture advection mechanism that implements logical 3D grid structures by physical memory in the form of 2D textures. This approach results in fast read and write access to physical memory, independent of GPU architecture. Slice-based direct volume rendering is used for the final display. A real-time computation of gradients is employed to achieve volume illumination. Perception-guided volume shading methods are included, such as halos, cool/warm shading, or color-based depth cueing. The problems of clutter and occlusion are addressed by supporting a volumetric importance function that enhances features of the flow and reduces visual complexity in less interesting regions.Item Structure-aware Stylization of Mountainous Terrains(The Eurographics Association, 2017) Kratt, Julian; Eisenkeil, Ferdinand; Spicker, Marc; Wang, Yunhai; Weiskopf, Daniel; Deussen, Oliver; Matthias Hullin and Reinhard Klein and Thomas Schultz and Angela YaoWe present a method for the stylization of mountainous terrains that allows creating abstract representations in different rendering styles. Our method consists of two major components: structure-aware terrain filtering and streamline-based hatching. For a given input terrain we compute different Levels-of-Detail (LoD) according to a crest line oriented importance measure and then filter each LoD accordingly. We generate flow fields for each LoD and compute streamlines to direct the production of hatching lines. The combination of crest and silhouette lines with streamline-based hatching allows us to create a variety of styles in different Levels-of-Detail. We evaluate our method using several terrains and demonstrate the effectiveness of our method by composing a number of different illustration styles.