vriphys14

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https://diglib.eg.org/handle/10.2312/7754

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Browsing vriphys14 by Subject "I.3.7 [Computer Graphics]"

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    Massively-Parallel Proximity Queries for Point Clouds
    (The Eurographics Association, 2014) Kaluschke, Max; Zimmermann, Uwe; Danzer, Marinus; Zachmann, Gabriel; Weller, Rene; Jan Bender and Christian Duriez and Fabrice Jaillet and Gabriel Zachmann
    We present a novel massively-parallel algorithm that allows real-time distance computations between arbitrary 3D objects and unstructured point cloud data. Our main application scenario is collision avoidance for robots in highly dynamic environments that are recorded via a Kinect, but our algorithm can be easily generalized for other applications such as virtual reality. Basically, we represent the 3D object by a bounding volume hierarchy, therefore we adopted the Inner Sphere Trees data structure, and we process all points of the point cloud in parallel using GPU optimized traversal algorithms. Additionally, all parallel threads share a common upper bound in the minimum distance, this leads to a very high culling efficiency. We implemented our algorithm using CUDA and the results show a real-time performance for online captured point clouds. Our algorithm outperforms previous CPU-based approaches by more than an order of magnitude.
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    A p-Multigrid Algorithm using Cubic Finite Elements for Efficient Deformation Simulation
    (The Eurographics Association, 2014) Weber, Daniel; Mueller-Roemer, Johannes; Altenhofen, Christian; Stork, Andre; Fellner, Dieter W.; Jan Bender and Christian Duriez and Fabrice Jaillet and Gabriel Zachmann
    We present a novel p-multigrid method for efficient simulation of co-rotational elasticity with higher-order finite elements. In contrast to other multigrid methods proposed for volumetric deformation, the resolution hierarchy is realized by varying polynomial degrees on a tetrahedral mesh. We demonstrate the efficiency of our approach and compare it to commonly used direct sparse solvers and preconditioned conjugate gradient methods. As the polynomial representation is defined w.r.t. the same mesh, the update of the matrix hierarchy necessary for co-rotational elasticity can be computed efficiently. We introduce the use of cubic finite elements for volumetric deformation and investigate different combinations of polynomial degrees for the hierarchy. We analyze the applicability of cubic finite elements for deformation simulation by comparing analytical results in a static scenario and demonstrate our algorithm in dynamic simulations with quadratic and cubic elements. Applying our method to quadratic and cubic finite elements results in speed up of up to a factor of 7 for solving the linear system.
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    SutureHap: A Suture Simulator with Haptic Feedback
    (The Eurographics Association, 2014) Ricardez, Eusebio; Noguez, Julieta; Neri, Luis; Munoz-Gomez, Lourdes; Escobar-Castillejos, David; Jan Bender and Christian Duriez and Fabrice Jaillet and Gabriel Zachmann
    Surgical procedures require a high degree of complexity and difficulty. Consequently, extensive preparation in the learning process of medical students is necessary in order to perform suturing tasks successfully. Some authors suggest that a minimum of 750 operations are needed to acquire the experience to perform correctly surgical procedures. Moreover, current laws establish standards if corpses and animals are used as medical learning environments; as a result, the development of skills and processes is hindered. This paper introduces the development of a virtual environment for training suture skills: SutureHap, which uses two Sensable Phantom Omni haptic devices. To create a proper simulation of the human skin which must fulfill graphic and physical characteristics, NVIDIA PhysX libraries were usea. Some of these libraries were originally defined to represent cloths; however, in this work some parameters were adjusted to obtain the desired simulation. An architecture that facilitates the integration of haptic devices was designed. A simplified method of collision detection and haptic feedback generation was created. This enabled the reduction of complexity generated during collision detection, and it diminished the time to develop the virtual environment. Tweezers, thread and needle models were added in the virtual environment. Due to fact that PhysX exploits GPU processing, response time was improved during modeling of the skin. Additionally, suturing tasks were designed by taking into consideration real procedures made by medical experts. The acquisition of skills and competencies in suture process are increased through haptic devices due to the fact that they can send tactile sensations. These environments decrease costs and risks, and provide real sensations as the ones that can be perceived in current learning environments. Finally, an evaluation focused on the perception of this environment was made by students. Preliminary results are promising, and it is expected that this environment facilitates the acquisition of suture skills.