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Item Fast Dynamic Simulation of Multi-Body Systems Using Impulses(The Eurographics Association, 2006) Bender, Jan; Schmitt, Alfred A.; Cesar Mendoza and Isabel NavazoA dynamic simulation method for multi-body systems is presented in this paper. The special feature of this method is that it satisfies all given constraints by computing impulses. In each simulation step the joint states after the step are predicted. In order to obtain valid states after the simulation step, impulses are computed and applied to the connected bodies. Since a valid joint state is targeted exactly, there is no drift as the simulation proceeds in time and so no additional stabilisation is required. In previous approaches the impulses for a multi-body system were computed iteratively. Since dependencies between joints were not taken into account, the simulation of complex models was slow. A novel method is presented that uses a system of linear equations to describe these dependencies. By solving this typically sparse system the required impulses are determined. This method allows a very fast simulation of complex multi-body systems.Item Motion Templates for Automatic Classification and Retrieval of Motion Capture Data(The Eurographics Association, 2006) Müller, Meinard; Röder, Tido; Marie-Paule Cani and James O'BrienThis paper presents new methods for automatic classification and retrieval of motion capture data facilitating the identification of logically related motions scattered in some database. As the main ingredient, we introduce the concept of motion templates (MTs), by which the essence of an entire class of logically related motions can be captured in an explicit and semantically interpretable matrix representation. The key property of MTs is that the variable aspects of a motion class can be automatically masked out in the comparison with unknown motion data. This facilitates robust and efficient motion retrieval even in the presence of large spatio-temporal variations. Furthermore, we describe how to learn an MT for a specific motion class from a given set of training motions. In our extensive experiments, which are based on several hours of motion data, MTs proved to be a powerful concept for motion annotation and retrieval, yielding accurate results even for highly variable motion classes such as cartwheels, lying down, or throwing motions.Item Re-using Traditional Animation: Methods for Semi-Automatic Segmentation and Inbetweening(The Eurographics Association, 2006) Juan, Christina N. de; Bodenheimer, Bobby; Marie-Paule Cani and James O'BrienA large body of traditional animation exists that contains characters with poses, expressions, and appeal not easily achievable with modern 3D techniques. To create new uses for this body of animation, this paper presents components of a system that can help incorporate the animation into re-usable libraries. In particular, we discuss two semi-automatic techniques that allow the re-use of traditional animation. First, support vector machines are used to segment cartoon images from their backgrounds for incorporation into an image library, for such applications as re-sequencing. Second, a radial basis function implicit surface modeling technique and a fast nonrigid elastic registration algorithm provide inbetween contours and textures given two key images of traditional animation. Our system is fast, model-free, and requires minimal animator intervention.