NPH09: Natural Phenomena 2009

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https://diglib.eg.org/handle/10.2312/276

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    Procedural Modeling of Leather Texture with Structural Elements
    (The Eurographics Association, 2009) Sakurai, Kaisei; Miyata, Kazunori; Kawai, Naoki; Matsufuji, Kazuo; Eric Galin and Jens Schneider
    This paper proposes a simple generation method for realistic leather texture. Leather surface consists of five structural elements, which are cristae, sulci, wrinkles, pockets and pores, which characterize the visual impression of the leather texture.We classified structural elements by observing real leather surface. To represent the elements, the method extracts features of real textures in order to generate an outline of each element. Then the method computes each element is three-dimensional shapes by a function which defines a continuous surface. Our method generates detailed leather texture, and is easy to handle, with simple procedures and intuitive parameters.
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    Interactive Modeling of Virtual Ecosystems
    (The Eurographics Association, 2009) Benes, Bedrich; Andrysco, Nathan; Stava, Ondrej; Eric Galin and Jens Schneider
    We present a novel technique for interactive, intuitive, and efficient modeling of virtual plants and plant ecosystems. Our approach is biologically-based, but shades the user from overwhelming input parameters by simplifying them to intuitive controls. Users are able to create scenes that are populated by virtual plants. Plants communicate actively with the environment and attempt to generate an optimal spatial distribution that dynamically adapts to neighboring plants, to user defined obstacles, light, and gravity. We demonstrate simulations of ecosystems composed of up to 140 trees that are computed in less than two minutes. Various phenomena previously available for non-realtime procedural approaches are created interactively, such as plants competing for space, topiary, plant lighting, virtual forests, etc. Results are aimed at architectural modeling, the entertainment industry, and everywhere that quick and fast creation of believable biological plant models is necessary.
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    Corotated SPH for Deformable Solids
    (The Eurographics Association, 2009) Becker, Markus; Ihmsen, Markus; Teschner, Matthias; Eric Galin and Jens Schneider
    Smoothed Particle Hydrodynamics (SPH) is a powerful technique for the animation of natural phenomena. While early SPH approaches in Computer Graphics have mainly been concerned with liquids or gases, recent research also focuses on the dynamics of deformable solids using SPH. In this paper, we present a novel corotational SPH formulation for deformable solids. The rigid body modes are extracted from the deformation field which allows to use a linear strain tensor. In contrast to previous rotationally invariant meshless approaches, we show examples using coplanar and collinear particle data sets. The presented approach further allows for a unified meshfree representation of deformable solids and fluids. This enables the animation of sophisticated phenomena, such as phase transitions. The versatility and the efficiency of the presented SPH scheme for deformable solids is illustrated in various experiments.
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    Real-Time Open Water Environments with Interacting Objects
    (The Eurographics Association, 2009) Cords, Hilko; Staadt, Oliver; Eric Galin and Jens Schneider
    Large bodies of water are an integral part of nature and, thus, are of high interest for interactive 3D applications, e.g., computer games and virtual environments. We present a new scheme for real-time wave simulation in large-scale water environments with physics-based object interaction. In addition to a fast and realistic liquid representation, our method focuses on the creation of plausible detailed waves caused by moving boats. We expand the well-known wave equation by applying it to moving grids to simulate an apparently limitless body of water. Additionally, we present a fast, particle-based boat simulation, which is coupled to water simulation. Importantly, most parts of our method can be implemented efficiently on GPUs. We demonstrate the visual realism and performance of our approach with several experiments using different boats and other floating objects, achieving high frame rates on a desktop PC.
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    A Geometric Algorithm for Snow Distribution in Virtual Scenes
    (The Eurographics Association, 2009) Festenberg, Niels v.; Gumhold, Stefan; Eric Galin and Jens Schneider
    Freshly fallen snow is a popular natural phenomenon able to evoke great beauty in all kinds of scenes. However, there still does not exist an all-purpose algorithm for automated snow distribution in virtual worlds. Previous works modelled snow either relying on costly particle simulations or oversimplified surface displacements. In this paper we develop a novel geometric snow model. In a first step, we propose a statistical snow deposition model inspired by real world observations. This statistical model is used to derive a geometric snow shape formulation. The geometric scheme is implemented with an enhanced height span map. Scene geometry is expressed with two parameter fields that enable us to efficiently compute snow cover geometry. A selection of snow covered scenes demonstrates the realism that can be achieved with this new method.