vriphys: Workshop in Virtual Reality Interactions and Physical Simulations

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Browsing vriphys: Workshop in Virtual Reality Interactions and Physical Simulations by Subject "Animation Keywords"

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    Approximate Air-Fluid Interactions for SPH
    (The Eurographics Association, 2017) Gissler, Christoph; Band, Stefan; Peer, Andreas; Ihmsen, Markus; Teschner, Matthias; Fabrice Jaillet and Florence Zara
    Computing the forces acting from a surrounding air phase onto an SPH free-surface fluid is challenging. For full multiphase simulations the computational overhead is significant and stability issues due to the high density ratio may arise. In contrast, the air-fluid interactions can be approximated efficiently by employing a drag equation. Here, for plausible effects, the parameterization is important but challenging. We present an approach to calculate the parameters of the used drag equation in a physically motivated way. We approximate the deformation and occlusion of particles to determine their drag coefficient and exposed surface area. The resulting effects are validated by comparing them to the results of a multiphase SPH simulation. We further show the practicality of our approach by combining it with different types of SPH solvers and by simulating multiple, complex scenes.
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    Moving Least Squares Boundaries for SPH Fluids
    (The Eurographics Association, 2017) Band, Stefan; Gissler, Christoph; Teschner, Matthias; Fabrice Jaillet and Florence Zara
    The paper shows that the SPH boundary handling of Akinci et al. [AIA 12] suffers from perceivable issues in planar regions due to deviations in the computed boundary normals and due to erroneous oscillations in the distance computation of fluid particles to the boundary. In order to resolve these issues, we propose a novel boundary handling that combines the SPH concept with Moving Least Squares. The proposed technique significantly improves the distance and normal computations in planar boundary regions, while its computational complexity is similar to Akinci's approach. We embed the proposed boundary handling into Implicit Incompressible SPH in a hybrid setting where it is applied at planar boundaries, while Akinci's technique is still being used for boundaries with complex shapes. Various benefits of the improved boundary handling are illustrated, in particular a reduced particle leakage and a reduced artificial boundary friction.
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    Real-time Landscape-size Convective Clouds Simulation and Rendering
    (The Eurographics Association, 2017) Goswami, Prashant; Neyret, Fabrice; Fabrice Jaillet and Florence Zara
    This paper presents an efficient, physics-based procedural model for the real-time animation and visualization of cumulus clouds at landscape size. We couple a coarse Lagrangian model of air parcels with a procedural amplification using volumetric noise. Our Lagrangian model draws an aerology i.e., the atmospheric physics of hydrostatic atmosphere with thermodynamics transforms, augmented by a model of mixing between parcels and environment. In addition to the particle-particle interactions, we introduce particle-implicit environment interactions. In contrast to the usual fluid simulation, we thus do not need to sample the transparent environment, a key property for real-time efficiency and scalability to large domains. Inheriting from the highlevel physics of aerology, we also validate our simulation by comparing it to predictive diagrams, and we show how the user can easily control key aspects of the result such as the cloud base and top altitude. Our model is thus fast, physical and controllable.