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Now showing 1 - 4 of 4
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    Steerable Texture Synthesis
    (Eurographics Association, 2004) Taponecco, Francesca; Alexa, Marc; M. Alexa and E. Galin
    Texture synthesis is typically concerned with the creation of an arbitrarily sized texture from a small sample, where the pattern of the generated texture should be perceived as resembling the example. Most of the current work follows a Markov model approach. The texture is generated by finding best matching pixels or patches in the sample and then copying them to the target. Here we extend this concept to incorporate arbitrary filters acting on the sample before matching and transferring. The filters may vary over the generated texture. Steering the filters with properties connected to the output image allows generating a variety of effects.
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    On Normals and Projection Operators for Surfaces Defined by Point Sets
    (The Eurographics Association, 2004) Alexa, Marc; Adamson, Anders; Markus Gross and Hanspeter Pfister and Marc Alexa and Szymon Rusinkiewicz
    Levin s MLS projection operator allows defining a surface from a set of points and represents a versatile procedure to generate points on this surface. Practical problems of MLS surfaces are a complicated non-linear optimization to compute a tangent frame and the (commonly overlooked) fact that the normal to this tangent frame is not the surface normal. An alternative definition of Point Set Surfaces, inspired by the MLS projection, is the implicit surface version of Adamson & Alexa.We use this surface definition to show how to compute exact surface normals and present simple, efficient projection operators. The exact normal computation also allows computing orthogonal projections.
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    Visual Component Analysis
    (The Eurographics Association, 2004) Müller, Wolfgang; Alexa, Marc; Oliver Deussen and Charles Hansen and Daniel Keim and Dietmar Saupe
    We propose to integrate information visualization techniques with factor analysis. Specifically, a principal direction derived from a principal component analysis (PCA) of the data is displayed together with the data in a scatterplot matrix. The direction can be adjusted to coincide with visual trends in the data. Projecting the data onto the orthogonal subspace allows determining the next direction. The set of directions identified in this way forms an orthogonal space, which represents most of the variation in the data. We call this process visual component analysis (VCA). Furthermore, it is quite simple to integrate VCA with clustering. The user fits poly-lines to the displayed data, and the poly-lines implicitly define clusters. Per-cluster projection leads to the definition of per-cluster components.
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    Point Based Animation of Elastic, Plastic and Melting Objects
    (The Eurographics Association, 2004) Müller, Matthias; Keiser, Richard; Nealen, Andrew; Pauly, Mark; Gross, Markus; Alexa, Marc; R. Boulic and D. K. Pai
    We present a method for modeling and animating a wide spectrum of volumetric objects, with material properties anywhere in the range from stiff elastic to highly plastic. Both the volume and the surface representation are point based, which allows arbitrarily large deviations form the original shape. In contrast to previous point based elasticity in computer graphics, our physical model is derived from continuum mechanics, which allows the specification of common material properties such as Young s Modulus and Poisson s Ratio. In each step, we compute the spatial derivatives of the discrete displacement field using a Moving Least Squares (MLS) procedure. From these derivatives we obtain strains, stresses and elastic forces at each simulated point. We demonstrate how to solve the equations of motion based on these forces, with both explicit and implicit integration schemes. In addition, we propose techniques for modeling and animating a point-sampled surface that dynamically adapts to deformations of the underlying volumetric model.