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Item Skeleton-based Joints Position Detection(The Eurographics Association, 2014) Madaras, Martin; Piovarci, Michal; Kovacovský, Tomás; Mathias Paulin and Carsten DachsbacherWe present a system for detection of joint positions in scans of articulated models. Our method is based purely on skeletons extracted from scanned point clouds of input models. First, skeletons are extracted from scans and then an estimation of possible matches between skeletons is performed. The matches are evaluated and sorted out. The whole matching process is fully automatic, but some user-driven suggestions can be included. Finally, we pick the best matching of skeletons and create a union-skeleton containing all the nodes from all the skeletons. We find nodes in the union-skeleton with rotation changes higher than the predefined threshold. We take these nodes as joints and visualize them in original scans.Item A Nonobscuring Eye Tracking Solution for Wide Field-of-View Head-mounted Displays(The Eurographics Association, 2014) Stengel, Michael; Grogorick, Steve; Rogge, Lorenz; Magnor, Marcus; Mathias Paulin and Carsten DachsbacherWe present a solution for integrating a binocular eye tracker into current state-of-the-art lens-based head-mounted displays (HMDs) without affecting the available field-of-view on the display. Estimating the relative eye gaze of the user opens the door for HMDs to a much wider spectrum of virtual reality applications and games. Further, we present a concept of a low-cost head-mounted display with eye tracking and discuss applications which strongly depend on or benefit from gaze estimation.Item Look me in the Eyes: A Survey of Eye and Gaze Animation for Virtual Agents and Artificial Systems(The Eurographics Association, 2014) Ruhland, K.; Andrist, S.; Badler, J. B.; Peters, C. E.; Badler, N. I.; Gleicher, M.; Mutlu, B.; McDonnell, R.; Sylvain Lefebvre and Michela SpagnuoloA person's emotions and state of mind are apparent in their face and eyes. As a Latin proverb states: ''The face is the portrait of the mind; the eyes, its informers.''. This presents a huge challenge for computer graphics researchers in the generation of artificial entities that aim to replicate the movement and appearance of the human eye, which is so important in human-human interactions. This State of the Art Report provides an overview of the efforts made on tackling this challenging task. As with many topics in Computer Graphics, a cross-disciplinary approach is required to fully understand the workings of the eye in the transmission of information to the user. We discuss the movement of the eyeballs, eyelids, and the head from a physiological perspective and how these movements can be modelled, rendered and animated in computer graphics applications. Further, we present recent research from psychology and sociology that seeks to understand higher level behaviours, such as attention and eye-gaze, during the expression of emotion or during conversation, and how they are synthesised in Computer Graphics and Robotics.Item State of the Art in Artistic Editing of Appearance, Lighting, and Material(The Eurographics Association, 2014) Schmidt, Thorsten-Walther; Pellacini, Fabio; Nowrouzezahrai, Derek; Jarosz, Wojciech; Dachsbacher, Carsten; Sylvain Lefebvre and Michela SpagnuoloMimicking the appearance of the real world is a longstanding goal of computer graphics, with several important applications in the feature-film, architecture and medical industries. Images with well-designed shading are an important tool for conveying information about the world, be it the shape and function of a CAD model, or the mood of a movie sequence. However, authoring this content is often a tedious task, even if undertaken by groups of highly-trained and experienced artists. Unsurprisingly, numerous methods to facilitate and accelerate this appearance editing task have been proposed, enabling the editing of scene objects' appearances, lighting, and materials, as well as entailing the introduction of new interaction paradigms and specialized preview rendering techniques. In this STAR we provide a comprehensive survey of artistic appearance, lighting, and material editing approaches. We organize this complex and active research area in a structure tailored to academic researchers, graduate students, and industry professionals alike. In addition to editing approaches, we discuss how user interaction paradigms and rendering backends combine to form usable systems for appearance editing. We conclude with a discussion of open problems and challenges to motivate and guide future research.Item Physically-based Simulation of Cuts in Deformable Bodies: A Survey(The Eurographics Association, 2014) Wu, Jun; Westermann, Rüdiger; Dick, Christian; Sylvain Lefebvre and Michela SpagnuoloVirtual cutting of deformable bodies has been an important and active research topic in physically-based simulation for more than a decade. A particular challenge in virtual cutting is the robust and efficient incorporation of cuts into an accurate computational model that is used for the simulation of the deformable body. This report presents a coherent summary of the state-of-the-art in virtual cutting of deformable bodies, focusing on the distinct geometrical and topological representations of the deformable body, as well as the specific numerical discretizations of the governing equations of motion. In particular, we discuss virtual cutting based on tetrahedral, hexahedral, and polyhedral meshes, in combination with standard, polyhedral, composite, and extended finite element discretizations. A separate section is devoted to meshfree methods. The report is complemented with an application study to assess the performance of virtual cutting simulators.Item Interactive Diffraction from Biological Nanostructures(The Eurographics Association, 2014) Dhillon, Daljit Singh; Teyssier, Jeremie; Single, Michael; Gaponenko, Iaroslav; Milinkovitch, Michel; Zwicker, Matthias; Mathias Paulin and Carsten DachsbacherWe describe a technique for interactive rendering of diffraction effects produced by biological nanostructures such as snake skin surface gratings. Our approach uses imagery from atomic force microscopy that accurately captures the nanostructures responsible for structural coloration, that is, coloration due to wave interference, in a variety of animals. We develop a rendering technique that constructs bidirectional reflection distribution functions (BRDFs) directly from the measured data and leverages precomputation to achieve interactive performance. We demonstrate results of our approach using various shapes of the surface grating nanostructures. Finally, we evaluate the accuracy of our precomputation-based technique and compare to a reference BRDF construction technique.Item SPH Fluids in Computer Graphics(The Eurographics Association, 2014) Ihmsen, Markus; Orthmann, Jens; Solenthaler, Barbara; Kolb, Andreas; Teschner, Matthias; Sylvain Lefebvre and Michela SpagnuoloSmoothed Particle Hydrodynamics (SPH) has been established as one of the major concepts for fluid animation in computer graphics. While SPH initially gained popularity for interactive free-surface scenarios, it has emerged to be a fully fledged technique for state-of-the-art fluid animation with versatile effects. Nowadays, complex scenes with millions of sampling points, one- and two-way coupled rigid and elastic solids, multiple phases and additional features such as foam or air bubbles can be computed at reasonable expense. This state-of-the-art report summarizes SPH research within the graphics community.Item The Split Grid - A Hierarchical 1D-Grid-based Acceleration Data Structure for Ray Tracing(The Eurographics Association, 2014) Bauszat, Pablo; Kastner, Marc Aurel; Eisemann, Martin; Magnor, Marcus; Mathias Paulin and Carsten DachsbacherWe present a new acceleration structure for ray tracing called the Split Grid. Combining concepts of hierarchical grids, kd-trees and Bounding Volume Hierarchies (BVHs), our approach is based on the idea of nesting 1D-grids. Our proposed acceleration structure is compact in storage, adaptive to the scene geometry and can be traversed using a fast and efficient traversal scheme. We show that the Split Grid is comparable to other current state-of-theart acceleration structures regarding traversal performance and memory footprint. While other data structures usually achieve these levels of performance only due to a complex and expensive construction process (e.g. using the Surface Area Heuristic (SAH) [MB90]), our proposed Split Grid is built with a very simplistic construction scheme which is a major benefit of our approach.