vriphys17

Permanent URI for this collection

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

Browse

Browsing vriphys17 by Subject "animation"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Inverse Kinematic Solutions for Articulated Characters using Massively Parallel Architectures and Differential Evolutionary Algorithms
    (The Eurographics Association, 2017) Kenwright, Ben; Fabrice Jaillet and Florence Zara
    This paper presents a Differential Evolutionary (DE) algorithm for solving multi-objective kinematic problems (e.g., end-effector locations, centre-of-mass and comfort factors). Inverse kinematic problems in the context of character animation systems are one of the most challenging and important conundrums. The problems depend upon multiple geometric factors in addition to cosmetic and physical aspects. Further complications stem from the fact that there may be non or an infinite number of solutions to the problem (especially for highly redundant manipulator structures, such as, articulated characters). What is more, the problem is global and tightly coupled so small changes to individual link's impacts the overall solution. Our method focuses on generating approximate solutions for a range of inverse kinematic problems (for instance, positions, orientations and physical factors, like overall centre-of-mass location) using a Differential Evolutionary algorithm. The algorithm is flexible enough that it can be applied to a range of open ended problems including highly non-linear discontinuous systems with prioritisation. Importantly, evolutionary algorithms are typically renowned for taking considerable time to find a solution. We help reduce this burden by modifying the algorithm to run on a massively parallel architecture (like the GPU) using a CUDA-based framework. The computational model is evaluated using a variety of test cases to demonstrate the techniques viability (speed and ability to solve multi-objective problems). The modified parallel evolutionary solution helps reduce execution times compared to the serial DE, while also obtaining a solution within a specified margin of error (<1%).
  • Thumbnail Image
    Item
    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.