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Now showing 1 - 10 of 12
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    Latency Considerations of Depth-first GPU Ray Tracing
    (The Eurographics Association, 2014) Guthe, Michael; Eric Galin and Michael Wand
    Despite the potential divergence of depth-first ray tracing [AL09], it is nevertheless the most efficient approach on massively parallel graphics processors. Due to the use of specialized caching strategies that were originally developed for texture access, it has been shown to be compute rather than bandwidth limited. Especially with recents developments however, not only the raw bandwidth, but also the latency for both memory access and read after write register dependencies can become a limiting factor. In this paper we will analyze the memory and instruction dependency latencies of depth first ray tracing. We will show that ray tracing is in fact latency limited on current GPUs and propose three simple strategies to better hide the latencies. This way, we come significantly closer to the maximum performance of the GPU.
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    Skeleton-based Joints Position Detection
    (The Eurographics Association, 2014) Madaras, Martin; Piovarci, Michal; Kovacovský, Tomás; Mathias Paulin and Carsten Dachsbacher
    We 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.
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    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 Dachsbacher
    We 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.
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    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 Spagnuolo
    A 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.
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    Deferred Shading for Order-Independent Transparency
    (The Eurographics Association, 2014) Hillesland, Karl E.; Bilodeau, Bill; Thibieroz, Nicolas; Eric Galin and Michael Wand
    Rendering many layers of transparency presents difficult challenges with respect to performance. Most previous work focused on the sorting problem, paying the full shading cost for all fragments. We present a method that defers shading until fragments can be classified as less important to the final pixel color, allowing us to switch to a lower-cost, approximate shading function. We apply this idea to TressFX, which is a state-of-the-art hair rendering technique used in video game production. For hair rendering, we switched to low-quality shading in all but the front eight fragments per pixel. This gave us a 75% speedup without noticeable loss in visual quality.
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    A User Study: Is the Advection Step in Shallow Water Equations Really Necessary?
    (The Eurographics Association, 2014) Kellomäki, Timo; Saari, Timo; Eric Galin and Michael Wand
    Heightfield methods, such as the pipe method and shallow water equations (SWE), have often been used to simulate large areas of water. Of these, the SWE are often preferred due to being more realistic, but they are also more complex and demand more computational resources than the pipe method. These two methods were presented to over 40 subjects in both a gaming and a video context to see whether they report noticing the advantages of SWE compared to the pipe method. No significant differences were observed in any of the categories measured (hedonic valence, flow, spatial presence, realism). Therefore, at least considering using the pipe method instead of the SWE is recommended. Also, varying the time step between 5 and 20 ms did not affect the user experience.
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    Regional Time Stepping for SPH
    (The Eurographics Association, 2014) Goswami, Prashant; Batty, Christopher; Eric Galin and Michael Wand
    This paper presents novel and efficient strategies to spatially adapt the amount of computational effort applied based on the local dynamics of a free surface flow, for classic weakly compressible SPH (WCSPH). Using a convenient and readily parallelizable block-based approach, different regions of the fluid are assigned differing time steps and solved at different rates to minimize computational cost. We demonstrate that our approach can achieve about two times speed-up over the standard method even in highly dynamic scenes.
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    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 Spagnuolo
    Mimicking 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.
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    Merging Live and pre-Captured Data to support Full 3D Head Reconstruction for Telepresence
    (The Eurographics Association, 2014) Fleury, Cedric; Popa, Tiberiu; Cham, Tat Jen; Fuchs, Henry; Eric Galin and Michael Wand
    This paper proposes a 3D head reconstruction method for low cost 3D telepresence systems that uses only a single consumer level hybrid sensor (color+depth) located in front of the users. Our method fuses the real-time, noisy and incomplete output of a hybrid sensor with a set of static, high-resolution textured models acquired in a calibration phase. A complete and fully textured 3D model of the users head can thus be reconstructed in real-time, accurately preserving the facial expression of the user. The main features of our method are a mesh interpolation and a fusion of a static and a dynamic textures to combine respectively a better resolution and the dynamic features of the face.
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    Physically-based Simulation of Cuts in Deformable Bodies: A Survey
    (The Eurographics Association, 2014) Wu, Jun; Westermann, Rüdiger; Dick, Christian; Sylvain Lefebvre and Michela Spagnuolo
    Virtual 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.