Computer Graphics Lab
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A Robust and Multi-scale Modal Analysis for Sound Synthesis C. Picard, F. Faure, G. Drettakis, P. G. Kry, DAFX, 2009 This paper presents a new approach to modal synthesis for rendering sounds of virtual objects. We propose a generic method for modal analysis that preserves sound variety across the surface of an object, at different scales of resolution and for a variety of complex geometries. The technique performs automatic voxelization of a surface model and automatic tuning of the parameters of hexahedral finite elements, based on the distribution of material in each cell. The voxelization is performed using a sparse regular grid embedding of the object, which easily permits the construction of plausible lower resolution approximations of the modal model. With our approach, we can compute the audible impulse response of a variety of objects. Our solution is robust and can handle non-manifold geometries that include both volumetric and surface parts, such as those used in games, training simulations, and other interactive virtual environment. PDF (2.7 MB) MOVIE |
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Preserving Topology and Elasticity for Embedded Deformable Models M. Nesme, P. G. Kry, L. Jeřábková, F. Faure, SIGGRAPH,2009 In this paper we introduce a new approach for the embedding of linear elastic deformable models. Our technique results in significant improvements in the efficient physically based simulation of highly detailed objects. First, our embedding takes into account topological details, that is, disconnected parts that fall into the same coarse element are simulated independently. Second, we account for the varying material properties by computing stiffness and interpolation functions for coarse elements which accurately approximate the behavior of the embedded material. Finally, we also take into account empty space in the coarse embeddings, which provides a better simulation of the boundary. The result is a straightforward approach to simulating complex deformable models with the ease and speed associated with a coarse regular embedding, and with a quality of detail that would only be possible at much finer resolution. PROJECT PAGE PDF (5 MB) MOVIE [DivX AVI] (29.2 MB) |
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Modal Locomotion: Animating Virtual Characters with Natural Vibrations P. G. Kry, L. Reveret, F. Faure, and M.-P.Cani, Eurographics,2009 We present a general method to intuitively create a wide range of locomotion controllers for 3D legged characters. The key of our approach is the assumption that efficient locomotion can exploit the natural vibration modes of the body, where these modes are related to morphological parameters such as the shape, size, mass, and joint stiffness. The vibration modes are computed for a mechanical model of any 3D character with rigid bones, elastic joints, and additional constraints as desired. A small number of vibration modes can be selected with respect to their relevance to locomotion patterns and combined into a compact controller driven by very few parameters. We show that these controllers can be used in dynamic simulations of simple creatures, and for kinematic animations of more complex creatures of a variety of shapes and sizes. PDF (0.7MB) MOVIE [XVID AVI] (17MB) DOG TROT [WMV] (1.7MB) DOG GALLOP [WMV] (1.1MB) |
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HandNavigator:
Hands-on Interaction for Desktop Virtual Reality P. G. Kry, A. Pihuit, A. Bernhert, and M.-P. Cani, VRST, 2008 This paper presents a novel interaction system, aimed at hands-on manipulation of digital models through natural hand gestures. Our system is composed of a new physical interaction device coupled with a simulated compliant virtual hand model. The physical interface consists of a SpaceNavigator, augmented with pressure sensors to detect directional forces applied by the user's fingertips. This information controls the position, orientation, and posture of the virtual hand in the same way that the SpaceNavigator (an isometric input device) uses measured forces to animate a virtual frame. In this manner, user control does not involve fatigue due to reaching gestures or holding a desired hand shape. During contact, the user has a realistic visual feedback in the form of plausible interactions between the virtual hand and its environment, while our device provides some passive tactile feedback. Our device is well suited to any situation where hand gesture, contact, or manipulation tasks need to be performed in virtual. We demonstrate the device in several simple virtual worlds and evaluate it through a series of user studies. PDF (4MB) MOVIE [MOV] (7MB) |
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Animating Virtual
Character Locomotion and Other Oscillatory Motions P. G. Kry, L. Reveret, F. Faure, M.-P.Cani Cognitive Animation Workshop 2008 / SIGGRAPH Sketches 2007 We present a method for animating locomotion of physically based virtual characters. The key to our approach is based on the observation that efficient locomotion should exploit the natural passive response of the character's dynamical system. We specifically focus on the natural vibration modes, which are affected by parameters such as shape, size, mass, and joint stiffness. From these modal vibrations we can extract the most promising modes with respect to locomotion, and combine them with different amplitudes, phases, and frequencies to animate various gaits. To create locomotion controllers, the search for control parameters is reduced since we only need to consider a small number of modes rather than a large number of degrees of freedom. This can be done by optimization, guided by captured motion analysis, but is also easy enough to do by hand. Mode shapes are also useful as a low dimensional basis for interactive puppetry, and may lead to simplifications in the higher level control of other movements. PDF (1MB) |