vriphys17

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https://diglib.eg.org/handle/10.2312/2631244

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Browsing vriphys17 by Subject "Computational Geometry and Object Modeling"

Now showing 1 - 4 of 4
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    Elasticity-based Clustering for Haptic Interaction with Heterogeneous Deformable Objects
    (The Eurographics Association, 2017) Gouis, Benoît Le; Marchal, Maud; Lécuyer, Anatole; Arnaldi, Bruno; Fabrice Jaillet and Florence Zara
    Physically-based simulation of heterogeneous objects remains computationally-demanding for many applications, especially when involving haptic interaction with virtual environments. In this paper, we introduce a novel multiresolution approach for haptic interaction with heterogeneous deformable objects. Our method called "Elasticity-based Clustering" is based on the clustering and aggregation of elasticity inside an object, in order to create large homogeneous volumes preserving important features of the initial distribution. The design of such large and homogeneous volumes improves the attribution of elasticity to the elements of the coarser geometry. We could successfully implement and test our approach within a complete and real-time haptic interaction pipeline compatible with consumer-grade haptic devices. We evaluated the performance of our approach on a large set of elasticity configurations using a perception-based quality criterion. Our results show that for 90% of studied cases our method can achieve a 6 times speedup in the simulation time with no theoretical perceptual difference.
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    A Fast Linear Complementarity Problem (LCP) Solver for Separating Fluid-Solid Wall Boundary Conditions
    (The Eurographics Association, 2017) Andersen, Michael; Niebe, Sarah; Erleben, Kenny; Fabrice Jaillet and Florence Zara
    We address the task of computing solutions for a separating fluid-solid wall boundary condition model. We present an embarrassingly parallel, easy to implement, fluid LCP solver.We are able to use greater domain sizes than previous works have shown, due to our new solver. The solver exploits matrix-vector products as computational building blocks. We block the matrix-vector products in a way that allows us to evaluate the products, without having to assemble the full systems. Any iterative sub-solver can be used. Our work shows speedup factors ranging up to 500 for larger grid sizes.
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    Implicit Mesh Generation using Volumetric Subdivision
    (The Eurographics Association, 2017) Altenhofen, Christian; Schuwirth, Felix; Stork, André; Fellner, Dieter W.; Fabrice Jaillet and Florence Zara
    In this paper, we present a novel approach for a tighter integration of 3D modeling and physically-based simulation. Instead of modeling 3D objects as surface models, we use a volumetric subdivision representation. Volumetric modeling operations allow designing 3D objects in similar ways as with surface-based modeling tools. Encoding the volumetric information already in the design mesh drastically simplifies and speeds up the mesh generation process for simulation. The transition between design, simulation and back to design is consistent and computationally cheap. Since the subdivision and mesh generation can be expressed as a precomputable matrix-vector multiplication, iteration times can be greatly reduced compared to common modeling and simulation setups. Therefore, this approach is especially well suited for early-stage modeling or optimization use cases, where many geometric changes are made in a short time and their physical effect on the model has to be evaluated frequently. To test our approach, we created, simulated and adapted several 3D models. Additionally, we measured and evaluated the timings for generating and applying the matrices for different subdivision levels. For comparison, we also measured the tetrahedral meshing functionality offered by CGAL for similar numbers of elements. For changing topology, our implicit meshing approach proves to be up to 70 times faster than creating the tetrahedral mesh only based on the outer surface. Without changing the topology and by precomputing the matrices, we achieve a speed-up of up to 2800.
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    Unified Simulation of Rigid and Flexible Bodies Using Position Based Dynamics
    (The Eurographics Association, 2017) Frâncu, Mihai; Moldoveanu, Florica; Fabrice Jaillet and Florence Zara
    In this paper we present a new position based approach for simulating rigid and flexible bodies with two-way coupling. This is achieved by expressing all the dynamics as constraints and running them in the same solver. Our main contribution is an accurate contact and Coulomb friction model based on a fixed point iteration of a cone complementarity problem. We formulate the problem as a nonlinear convex minimization at position level and solve it using a new accelerated form of projected Jacobi. We add elasticity to the constraints by means of regularization and show how to add more damping in a credible manner. We also use this viscoelastic model to build an accurate position-based finite element solver for soft bodies. The novelty of this solver is that it is no longer an approximation and it is based directly on the elasticity theory of continuous media.