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    Fast Continuous Collision Detection among Deformable Models using Graphics Processors
    (The Eurographics Association, 2006) Govindaraju, Naga K.; Kabul, Ilknur; Lin, Ming C.; Manocha, Dinesh; Ming Lin and Roger Hubbold
    We present an interactive algorithm to perform continuous collision detection between general deformable models using graphics processors (GPUs). We model the motion of each object in the environment as a continuous path and check for collisions along the paths. Our algorithm precomputes the chromatic decomposition for each object and uses visibility queries on GPUs to quickly compute potentially colliding sets of primitives. We introduce a primitive classification technique to perform efficient continuous self-collision. We have implemented our algorithm on a 3:0 GHz Pentium IV PC with a NVIDIA 7800 GPU, and we highlight its performance on complex simulations composed of several thousands of triangles. In practice, our algorithm is able to detect all contacts, including self-collisions, at image-space precision in tens of milli-seconds.
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    Constellation Models for Sketch Recognition
    (The Eurographics Association, 2006) Sharon, Dana; Panne, Michiel van de; Thomas Stahovich and Mario Costa Sousa
    Sketch-based modeling shares many of the difficulties of the branch of computer vision that deals with single image interpretation. Most obviously, they must both identify the parts observed in a given 2D drawing or image.We draw on constellation models first proposed in the computer vision literature to develop probabilistic models for object sketches, based on multiple example drawings. These models are then applied to estimate the most-likely labels for a new sketch. A multi-pass branch-and-bound algorithm allows well-formed sketches to be quickly labelled, while still supporting the recognition of more ambiguous sketches. Results are presented for five classes of objects.
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    Sense-Enabled Mixed Reality Museum Exhibitions
    (The Eurographics Association, 2007) Liarokapis, Fotis; Newman, Robert M.; Mount, Sarah; Goldsmith, Dan; Macan, Luis; Malone, Garry; Shuttleworth, James; D. Arnold and F. Niccolucci and A. Chalmers
    During the past few years museums and other cultural heritage institutions have started making use of handheld technologies to provide tourist guides to their visitors. For open-air sites, a number of experimental and commercial applications have been developed based on location-based guides. However, in museum environments static audiovisual guides are the dominant technologies used. In this paper, we present a novel pervasive mixed reality framework to a sensor network capturing ambient noise that can be used to create tangible cultural heritage exhibitions. Localisation of the visitors can be established in a hybrid manner based on machine vision and a wireless sensor network allowing visitors to interact naturally or with the help of sensors. In terms of interface design, a multimodal mixed reality visualisation domain allows for an audio-visual presentation of cultural heritage artefacts.
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    Consistent Scene Illumination using a Chromatic Flash
    (The Eurographics Association, 2009) Kim, Min H.; Kautz, Jan; Oliver Deussen and Peter Hall
    Flash photography is commonly used in low-light conditions to prevent noise and blurring artifacts. However, flash photography commonly leads to a mismatch between scene illumination and flash illumination, due to the bluish light that flashes emit. Not only does this change the atmosphere of the original scene illumination, it also makes it difficult to perform white balancing because of the illumination differences. Professional photographers sometimes apply colored gel filters to the flashes in order to match the color temperature. While effective, this is impractical for the casual photographer. We propose a simple but powerful method to automatically match the correlated color temperature of the auxiliary flash light with that of scene illuminations allowing for well-lit photographs while maintaining the atmosphere of the scene. Our technique consists of two main components. We first estimate the correlated color temperature of the scene, e.g., during image preview. We then adjust the color temperature of the flash to the scene's correlated color temperature, which we achieve by placing a small trichromatic LCD in front of the flash. We demonstrate the effectiveness of this approach with a variety of examples.
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    Effect of visual cues on human performance in navigating through a virtual maze
    (The Eurographics Association, 2004) Vembar, D.; Iyengar, N.; Duchowski, A.; Clark, K.; Hewitt, J.; Pauls, K.; Sabine Coquillart and Martin Goebel
    Navigation in Virtual Environments (VEs) requires users to develop spatial knowledge of the environment primarily through visual cues provided to the user. Thus, the design and display of visual navigation cues is important for efficient navigation in a VE. In this paper, we report the results of an experiment in which three different visual cues were tested for their benefit toward users' navigation in a 3D virtual maze. The experiment varied the form of visual cue: a 2D map, a 2D map with a directionally ambiguous cue, and a 2D map with a directional cue. Eye tracking data was collected and analyzed to examine the correlation between the type of visual cue presented and the navigational efficiency of the user through the virtual maze. It was observed that the cue type affected performance of the participant in the 3D maze. The directional cue was most effective in the time taken by users to reach the center of the maze. Results of this study have implications for VE design as well as for game development.
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    Haptic Simulation, Perception and Manipulation of Deformable Objects
    (The Eurographics Association, 2007) Magnenat-Thalmann, Nadia; Volino, Pascal; Bonanni, Ugo; Summers, Ian R.; Brady, A. C.; Qu, J.; Allerkamp, D.; Fontana, M.; Tarri, F.; Salsedo, F.; Bergamasco, Massimo; Karol Myszkowski and Vlastimil Havran
    This tutorial addresses haptic simulation, perception and manipulation of complex deformable objects in virtual environments (VE). We first introduce HAPTEX, a research project dealing with haptic simulation and perception of textiles in VEs. Then, we present state-of-the-art techniques concerning haptic simulation and rendering, ranging from physically based modelling to control issues of tactile arrays and force-feedback devices. In the section on cloth simulation for haptic systems we describe techniques for simulating textiles adapted to the specific context of haptic applications. The section concerning tactile aspects of virtual objects shows how arrays of contactors on the skin can be used to provide appropriate spatiotemporal patterns of mechanical excitation to the underlying mechanoreceptors. Finally, the last section addresses the problem of developing suitable force feedback technologies for the realistic haptic rendering of the physical interaction with deformable objects, addressing the design of novel force feedback systems, innovative concepts for curvature simulation and control algorithms for accuracy improvement.
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    Wind projection basis for real-time animation of trees
    (The Eurographics Association and Blackwell Publishing Ltd, 2009) Diener, Julien; Rodriguez, Mathieu; Baboud, Lionel; Reveret, Lionel
    This paper presents a real-time method to animate complex scenes of thousands of trees under a user-controllable wind load. Firstly, modal analysis is applied to extract the main modes of deformation from the mechanical model of a 3D tree. The novelty of our contribution is to precompute a new basis of the modal stress of the tree under wind load. At runtime, this basis allows to replace the modal projection of the external forces by a direct mapping for any directional wind. We show that this approach can be efficiently implemented on graphics hardware. This modal animation can be simulated at low computation cost even for large scenes containing thousands of trees.
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    Total Recall: A Debugging Framework for GPUs
    (The Eurographics Association, 2008) Sharif, Ahmad; Lee, Hsien-Hsin S.; David Luebke and John Owens
    GPUs have transformed from simple fixed-function processors to powerful, programmable stream processors and are continuing to evolve. Programming these massively parallel GPUs, however, is very different from programming a sequential CPU. Lack of native support for debugging coupled with the parallelism in the GPU makes program development for the GPU a non-trivial task. As GPU programs grow in complexity because of scaling in maximum allowed program size and increased demand in terms of realism, debugging GPU code is becoming a major timesink for content developers. In addition to more complex shaders, applications are using multi-pass effects in order to create more convincing reality. In this paper, we present a debugging framework that can be employed to debug complex code running on the GPU in an efficient manner. By observing the API calls of the application that are made to the 3D runtime, the framework can keep track of the program's state in memory. Upon the programmer's request, it is able to capture and deterministically replay the stream of instructions that caused the final write to a pixel of interest. This execution stream includes writes to intermediate render targets and spans across shader boundaries. The stream of instructions can then be replayed on the CPU via emulation and the programmer can debug the straight-line code with ease. We also present a hardware-friendly scheme that can be used to accelerate the debugging process for long-chain multi-pass effects.
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    On the Evolution of Geometrical Reconstruction as a Core Technology to Sketch-Based Modeling
    (The Eurographics Association, 2004) Company, Pedro; Piquer, Ana; Contero, Manuel; Joaquim Armando Pires Jorge and Eric Galin and John F. Hughes
    In this work, the background and evolution of three-dimensional reconstruction of line drawing over the last thirty years is discussed. A new general taxonomy is proposed to describe and discuss the historical evolution of geometrical reconstruction and its challenges. The evolution of geometrical reconstruction from recovering know-how stored in engineering drawings to sketch-based modeling for helping in the first steps of conceptual design purposes, and the current challenges of geometrical reconstruction are also discussed.
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    Achieving Good Connectivity in Motion Graphs
    (The Eurographics Association, 2008) Zhao, Liming; Safonova, Alla; Markus Gross and Doug James
    Motion graphs provide users with a simple yet powerful way to synthesize human motions. While motion graphbased synthesis has been widely successful, the quality of the generatedmotion depends largely on the connectivity of the graph and the quality of transitions in it. However, achieving both of these criteria simultaneously in motion graphs is difficult. Good connectivity requires transitions between less similar poses, while good motion quality results only when transitions happen between very similar poses. This paper introduces a new method for building motion graphs. The method first builds a set of interpolated motion clips, which contain many more similar poses than the original dataset. Using this set, the method then constructs a motion graph and reduces its size by minimizing the number of interpolated poses present in the graph. The outcome of the algorithm is a motion graph called a well-connected motion graph with very good connectivity and only smooth transitions. Our experimental results show that well-connected motion graphs outperform standardmotion graphs across a number of measures, result in very good motion quality, allow for high responsiveness when used for interactive control, and even do not require post-processing of the synthesizedmotions