Browsing by Type "technical sketch"
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Item A semi-Lagrangian contouring method for fluid simulation(ACM, 2005-08-04) Bargteil, Adam W.; Goktekin, Tolga G.; O’Brien, James F.; Strain, John A.In this sketch we present a semi-Lagrangian surface tracking method for use with fluid simulations. Our method maintains an explicit polygonal mesh that defines the surface, and an octree data structure that provides both a spatial index for the mesh and an efficient means for evaluating the signeddistance function away from the surface. At each time step the surface is reconstructed from an implicit function defined by the composition of backward advection and the previous signed-distance function. One of the primary advantages of this formulation is that it enables tracking of surface characteristics, such as color or texture coordinates, at negligible additional cost. We include several examples demonstrating that the method can be used as part of a fluid simulation to effectively animate complex and interesting fluid behaviors.Item A Texture Synthesis Method for Liquid Animations(ACM, 2006-08-03) Bargteil, Adam W.; Sin, Funshing; Michaels, Jonathan E.; Goktekin, Tolga G.; O’Brien, James F.Liquid simulation techniques have become a standard tool in production environments, producing extremely realistic liquid motion in a variety of films, commercials, and video games. Surface texturing is an essential computer graphics tool, which gives artists additional control over their results by allowing them to stylize surfaces or add detail to a lowresolution simulations. For example, an artist could use texturing techniques to add the appearance of foam to a wave, bubbles to beer, or fat globules to soup. Unfortunately, texturing liquid surfaces is difficult because the surfaces have no inherent parameterization. Creating a temporally consistent parameterization is extremely difficult for two primary reasons. First, liquid simulations are characterized by their complex and frequent topological changes. These topological changes result in significant discontinuities in any parameter tracked on the surface. Second, liquid surfaces tend to stretch and compress dramatically over the course of a simulation. Similarly, an advected parameterization will also stretch and compress. For these reasons, advected texture coordinates are often unsuitable for texturing liquid surfaces. In this sketch we present a method for generating textures on animated liquid surfaces. Rather than advecting texture coordinates on the surface, we synthesize a new texture at every frame. We initialize the texture with color values advected from the surface at the previous frame. We then run an optimization procedure which attempts to match the surface texture to an input sample texture and, for temporal coherence, the advected colors.