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Item Real Time Animation of Virtual Humans: A Trade-off Between Naturalness and Control(The Eurographics Association and Blackwell Publishing Ltd, 2010) Van Welbergen, H.; Van Basten, B. J. H.; Egges, A.; Ruttkay, Zs. M.; Overmars, M. H.Virtual humans are employed in many interactive applications using 3D virtual environments, including (serious) games. The motion of such virtual humans should look realistic (or natural and allow interaction with the surroundings and other (virtual) humans. Current animation techniques differ in the trade-off they offer between motion naturalness and the control that can be exerted over the motion. We show mechanisms to parametrize, combine (on different body parts) and concatenate motions generated by different animation techniques. We discuss several aspects of motion naturalness and show how it can be evaluated. We conclude by showing the promise of combinations of different animation paradigms to enhance both naturalness and control.Item An Eyeglass Simulator Using Conoid Tracing(The Eurographics Association and Blackwell Publishing Ltd, 2010) Kakimoto, M.; Tatsukawa, T.; Nishita, T.This paper proposes a method for displaying images at the fovea of the retina taking visual acuity into account. Previous research has shown that a point light source projected onto the retina forms an ellipse, which can be computed with wavefront tracing from each point in space. We propose a novel concept using conoid tracing, with which we can acquire defocusing information several times faster than that acquired by previous methods. We also show that conoid tracing is more robust and produces higher quality results. In conoid tracing the ray is regarded as a conoid, a thin cone-like shape with varying elliptical cross-section. The viewing ray from the retina is traced as a conoid and evaluated at each sample location. Using the sampled and pre-computed data for the spatial distribution of blurring, we implemented an interactive eyeglass simulator. This paper demonstrates some visualization results utilizing the interactivity of the simulator, which an eyeglass lens design company uses to evaluate the design of complex progressive lenses.Item Chain Shape Matching for Simulating Complex Hairstyles(The Eurographics Association and Blackwell Publishing Ltd, 2010) Rungjiratananon, W.; Kanamori, Y.; Nishita, T.Animations of hair dynamics greatly enrich the visual attractiveness of human characters. Traditional simulation techniques handle hair as clumps or continuum for efficiency; however, the visual quality is limited because they cannot represent the fine-scale motion of individual hair strands. Although a recent mass-spring approach tackled the problem of simulating the dynamics of every strand of hair, it required a complicated setting of springs and suffered from high computational cost. In this paper, we base the animation of hair on such a fine-scale on Lattice Shape Matching (LSM), which has been successfully used for simulating deformable objects. Our method regards each strand of hair as a chain of particles, and computes geometrically derived forces for the chain based on shape matching. Each chain of particles is simulated as an individual strand of hair. Our method can easily handle complex hairstyles such as curly or afro styles in a numerically stable way. While our method is not physically based, our GPU-based simulator achieves visually plausible animations consisting of several tens of thousands of hair strands at interactive rates.Item Electrostatic Halftoning(The Eurographics Association and Blackwell Publishing Ltd, 2010) Schmaltz, Christian; Gwosdek, Pascal; Bruhn, Andres; Weickert, JoachimWe introduce a new global approach for image dithering, stippling, screening and sampling. It is inspired by the physical principles of electrostatics. Repelling forces between equally charged particles create a homogeneous distribution in flat areas, while attracting forces from the image brightness values ensure a high approximation quality. Our model is transparent and uses only two intuitive parameters: One steers the granularity of our halftoning approach, and the other its regularity. We evaluate two versions of our algorithm: A discrete version for dithering that ties points to grid positions, as well as a continuous one which does not have this restriction, and can thus be used for stippling or sampling density functions. Our methods create very few visual artefacts, reveal favourable blue-noise behaviour in the frequency domain, and have a lower approximation error under Gaussian convolution than state-of-the-art methods.Item A Key-Pose Caching System for Rendering an Animated Crowd in Real-Time(The Eurographics Association and Blackwell Publishing Ltd, 2010) Lister, W.; Laycock, R.G.; Day, A.M.We present a method to accelerate the visualization of large crowds of animated characters. Linear-blend skinning remains the dominant approach for animating a crowd but its efficiency can be improved by utilizing the temporal and intra-crowd coherencies that are inherent within a populated scene. Our work adopts a caching system that enables a skinned key-pose to be re-used by multi-pass rendering, between multiple agents and across multiple frames. We investigate two different methods; an intermittent caching scheme (whereby each member of a crowd is animated using only its nearest key-pose) and an interpolative approach that enables key-pose blending to be supported. For the latter case, we show that finding the optimal set of key-poses to store is an NP-hard problem and present a greedy algorithm suitable for real-time applications. Both variants deliver a worthwhile performance improvement in comparison to using linear-blend skinning alone.Item Virtual Video Camera: Image-Based Viewpoint Navigation Through Space and Time(The Eurographics Association and Blackwell Publishing Ltd, 2010) Lipski, C.; Linz, C.; Berger, K.; Sellent, A.; Magnor, M.We present an image-based rendering system to viewpoint-navigate through space and time of complex real-world, dynamic scenes. Our approach accepts unsynchronized, uncalibrated multivideo footage as input. Inexpensive, consumer-grade camcorders suffice to acquire arbitrary scenes, for example in the outdoors, without elaborate recording setup procedures, allowing also for hand-held recordings. Instead of scene depth estimation, layer segmentation or 3D reconstruction, our approach is based on dense image correspondences, treating view interpolation uniformly in space and time: spatial viewpoint navigation, slow motion or freeze-and-rotate effects can all be created in the same way. Acquisition simplification, integration of moving cameras, generalization to difficult scenes and space-time symmetric interpolation amount to a widely applicable virtual video camera system.Item Generalized Use of Non-Terminal Symbols for Procedural Modeling(The Eurographics Association and Blackwell Publishing Ltd, 2010) Krecklau, L.; Pavic, D.; Kobbelt, L.We present the new procedural modeling language, (Generalized Grammar), which adapts various concepts from general purpose programming languages to provide high descriptive power with well-defined semantics and a simple syntax which is easily readable even by non-programmers. The term Generalized reflects two kinds of generalization. On the one hand, we extend the scope of previous architectural modeling languages by allowing for multiple types of non-terminal objects with domain-specific operators and attributes. On the other hand, the language accepts non-terminal symbols as parameters in modeling rules and thus enables the definition of abstract structure templates for flexible re-use within the grammar. By deriving, from the well-established programming language Python, we can make sure that our modeling language has a well-defined semantics. For illustration, we apply, to architectural as well as plant modeling to demonstrate its descriptive power with some complex examples.Item Generating Classic Mosaics with Graph Cuts(The Eurographics Association and Blackwell Publishing Ltd, 2010) Liu, Y.; Veksler, O.; Juan, O.Classic mosaic is an old and durable art form. Generating artificial classic mosaics from digital images is an interesting problem that has attracted attention in recent years. Previous approaches to mosaic generation are largely based on heuristics, and therefore it is harder to analyse, predict and improve their performance. In addition, previous methods have a number of disadvantages, such as requiring that the number of tiles in a mosaic is known a priori, or relying on extensive user interaction, or using heuristics for tile placement that lead to visible artefacts. We propose a classic mosaic generation algorithm that is based on a principled global optimization. Our approach is fully automatic. We design and optimize an objective function that incorporates the desired mosaic properties, such as tile alignment to significant image edges, prohibiting tile overlap, etc. Our optimization method is based on graph cuts, which proved to be a powerful optimization tool in graphics and computer vision. Experimental comparison to previous work demonstrate the advantages of our approach.Item REPORT OF THE STATUTORY AUDITORS TO THE GENERAL MEETING OF THE MEMBERS OF EUROGRAPHICS ASSOCIATION GENEVA(The Eurographics Association and Blackwell Publishing Ltd, 2010)Item 3D Surface Reconstruction Using a Generalized Distance Function(The Eurographics Association and Blackwell Publishing Ltd, 2010) Poranne, R.; Gotsman, C.; Keren, D.We define a generalized distance function on an unoriented 3D point set and describe how it may be used to reconstruct a surface approximating these points. This distance function is shown to be a Mahalanobis distance in a higher-dimensional embedding space of the points, and the resulting reconstruction algorithm a natural extension of the classical Radial Basis Function (RBF) approach. Experimental results show the superiority of our reconstruction algorithm to RBF and other methods in a variety of practical scenarios.