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122
Skinning Mesh Animations
 ACM Trans. Graph
, 2005
"... We extend approaches for skinning characters to the general setting of skinning deformable mesh animations. We provide an automatic algorithm for generating progressive skinning approximations, that is particularly efficient for pseudoarticulated motions. Our contributions include the use of nonpar ..."
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Cited by 128 (6 self)
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We extend approaches for skinning characters to the general setting of skinning deformable mesh animations. We provide an automatic algorithm for generating progressive skinning approximations, that is particularly efficient for pseudoarticulated motions. Our contributions include the use of nonparametric mean shift clustering of highdimensional mesh rotation sequences to automatically identify statistically relevant bones, and robust least squares methods to determine bone transformations, bonevertex influence sets, and vertex weight values. We use a lowrank data reduction model defined in the undeformed mesh configuration to provide progressive convergence with a fixed number of bones. We show that the resulting skinned animations enable efficient hardware rendering, rest pose editing, and deformable collision detection. Finally, we present numerous examples where skins were automatically generated using a single set of parameter values.
Collision Detection for Deformable Objects
"... Interactive environments for dynamically deforming objects play an important role in surgery simulation and entertainment technology. These environments require fast deformable models and very efficient collision handling techniques. While collision detection for rigid bodies is wellinvestigated, c ..."
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Cited by 111 (18 self)
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Interactive environments for dynamically deforming objects play an important role in surgery simulation and entertainment technology. These environments require fast deformable models and very efficient collision handling techniques. While collision detection for rigid bodies is wellinvestigated, collision detection for deformable objects introduces additional challenging problems. This paper focuses on these aspects and summarizes recent research in the area of deformable collision detection. Various approaches based on bounding volume hierarchies, distance fields, and spatial partitioning are discussed. Further, imagespace techniques and stochastic methods are considered. Applications in cloth modeling and surgical simulation are presented.
Meshbased inverse kinematics
 ACM Trans. Graph
, 2005
"... The ability to position a small subset of mesh vertices and produce a meaningful overall deformation of the entire mesh is a fundamental task in mesh editing and animation. However, the class of meaningful deformations varies from mesh to mesh and depends on mesh kinematics, which prescribes valid m ..."
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Cited by 97 (8 self)
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The ability to position a small subset of mesh vertices and produce a meaningful overall deformation of the entire mesh is a fundamental task in mesh editing and animation. However, the class of meaningful deformations varies from mesh to mesh and depends on mesh kinematics, which prescribes valid mesh configurations, and a selection mechanism for choosing among them. Drawing an analogy to the traditional use of skeletonbased inverse kinematics for posing skeletons, we define meshbased inverse kinematics as the problem of finding meaningful mesh deformations that meet specified vertex constraints. Our solution relies on example meshes to indicate the class of meaningful deformations. Each example is represented with a feature vector of deformation gradients that capture the affine transformations which individual triangles undergo relative to a reference pose. To pose a mesh, our algorithm efficiently searches among all meshes with specified vertex positions to find the one that is closest to some pose in a nonlinear span of the example feature vectors. Since the search is not restricted to the span of example shapes, this produces compelling deformations even when the constraints require poses that are different from those observed in the examples. Furthermore, because the span is formed by a nonlinear blend of the example feature vectors, the blending component of our system may also be used independently to pose meshes by specifying blending weights or to compute multiway morph sequences.
BDTree: OutputSensitive Collision Detection for Reduced Deformable Models
 ACM Transactions on Graphics (SIGGRAPH
, 2004
"... We introduce the Bounded Deformation Tree, or BDTree, which can perform collision detection with reduced deformable models at costs comparable to collision detection with rigid objects. Reduced deformable models represent complex deformations as linear superpositions of arbitrary displacement field ..."
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Cited by 97 (11 self)
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We introduce the Bounded Deformation Tree, or BDTree, which can perform collision detection with reduced deformable models at costs comparable to collision detection with rigid objects. Reduced deformable models represent complex deformations as linear superpositions of arbitrary displacement fields, and are used in a variety of applications of interactive computer graphics. The BDTree is a bounding sphere hierarchy for outputsensitive collision detection with such models. Its bounding spheres can be updated after deformation in any order, and at a cost independent of the geometric complexity of the model; in fact the cost can be as low as one multiplication and addition per tested sphere, and at most linear in the number of reduced deformation coordinates. We show that the BDTree is also extremely simple to implement, and performs well in practice for a variety of realtime and complex offline deformable simulation examples.
Precomputing interactive dynamic deformable scenes
 ACM Trans. Graph
, 2003
"... dynamics by driving the scene with parameterized interactions representative of runtime usage. (b) Model reduction on observed dynamic deformations yields a lowrank approximation to the system’s parameterized impulse response functions. (c) Deformed state geometries are then sampled and used to pre ..."
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Cited by 84 (7 self)
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dynamics by driving the scene with parameterized interactions representative of runtime usage. (b) Model reduction on observed dynamic deformations yields a lowrank approximation to the system’s parameterized impulse response functions. (c) Deformed state geometries are then sampled and used to precompute and coparameterize a radiance transfer model for deformable objects. (d) The final simulation responds plausibly to interactions similar to those precomputed, includes complex collision and global illumination effects, and runs in real time. We present an approach for precomputing datadriven models of interactive physically based deformable scenes. The method permits realtime hardware synthesis of nonlinear deformation dynamics, including selfcontact and global illumination effects, and supports realtime user interaction. We use datadriven tabulation of the system’s deterministic state space dynamics, and model reduction to build efficient lowrank parameterizations of the deformed shapes. To support runtime interaction, we also tabulate impulse response functions for a palette of external excitations. Although our approach simulates particular systems under very particular interaction conditions, it has several advantages. First, parameterizing all possible scene deformations enables us to precompute novel reduced coparameterizations of global scene illumination for lowfrequency lighting conditions. Second, because the deformation dynamics are precomputed and parameterized as a whole, collisions are resolved within the scene during precomputation so that runtime selfcollision handling is implicit. Optionally, the datadriven models can be synthesized on programmable graphics hardware, leaving only the lowdimensional state space dynamics and appearance data models to be computed by the main CPU.
Recent Advances in Mesh Morphing
, 2002
"... Meshes have become a widespread and popular representation of models in computer graphics. Morphing techniques aim at transforming a given source shape into a target shape. Morphing techniques have various applications ranging from special effects in television and movies to medical imaging and sc ..."
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Cited by 79 (0 self)
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Meshes have become a widespread and popular representation of models in computer graphics. Morphing techniques aim at transforming a given source shape into a target shape. Morphing techniques have various applications ranging from special effects in television and movies to medical imaging and scientific visualization. Not surprisingly, morphing techniques for meshes have received a lot of interest lately.
Geostatistical Motion Interpolation
 ACM Transactions on Graphics
, 2005
"... Figure 1: Animations synthesized by our motion interpolation in a 5D parametric space. One parameter changes the style of motion from rough to delicate as shown by the bar indicator. The other four parameters are the heights and widths of two successive steps of stairs for gait motions, and the 2D s ..."
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Cited by 69 (5 self)
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Figure 1: Animations synthesized by our motion interpolation in a 5D parametric space. One parameter changes the style of motion from rough to delicate as shown by the bar indicator. The other four parameters are the heights and widths of two successive steps of stairs for gait motions, and the 2D start and end locations of the box for lifting motions. None of the motions required postcleaning of foot or handsliding. A common motion interpolation technique for realistic human animation is to blend similar motion samples with weighting functions whose parameters are embedded in an abstract space. Existing methods, however, are insensitive to statistical properties, such as correlations between motions. In addition, they lack the capability to quantitatively evaluate the reliability of synthesized motions. This paper proposes a method that treats motion interpolations as statistical predictions of missing data in an arbitrarily definable parametric space. A practical technique of geostatistics, called universal kriging, is then introduced for statistically estimating the correlations between the dissimilarity of motions and the distance
Geometry Videos: A New Representation for 3D Animations
, 2003
"... We present the “Geometry Video,” a new data structure to encode animated meshes. Being able to encode animated meshes in a generic sourceindependent format allows people to share experiences. Changing the viewpoint allows more interaction than the fixed view supported by 2D video. Geometry videos a ..."
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Cited by 69 (1 self)
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We present the “Geometry Video,” a new data structure to encode animated meshes. Being able to encode animated meshes in a generic sourceindependent format allows people to share experiences. Changing the viewpoint allows more interaction than the fixed view supported by 2D video. Geometry videos are based on the “Geometry Image” mesh representation introduced by Gu et al. 4. Our novel data structure provides a way to treat an animated mesh as a video sequence (i.e., 3D image) and is well suited for network streaming. This representation also offers the possibility of applying and adapting existing mature video processing and compression techniques (such as MPEG encoding) to animated meshes. This paper describes an algorithm to generate geometry videos from animated meshes. The main insight of this paper, is that Geometry Videos resample and reorganize the geometry information, in such a way, that it becomes very compressible. They provide a unified and intuitive method for levelofdetail control, both in terms of mesh resolution (by scaling the two spatial dimensions) and of frame rate (by scaling the temporal dimension). Geometry Videos have a very uniform and regular structure. Their resource and computational requirements can be calculated exactly, hence making them also suitable for applications requiring level of service guarantees.
Turning to the Masters: Motion Capturing Cartoons
, 2002
"... In this paper, we present a technique we call "cartoon capture and retargeting" which we use to track the motion from traditionally animated cartoons and retarget it onto 3D models, 2D drawings, and photographs. By using animation as the source, we can produce new animations that are exp ..."
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Cited by 62 (0 self)
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In this paper, we present a technique we call "cartoon capture and retargeting" which we use to track the motion from traditionally animated cartoons and retarget it onto 3D models, 2D drawings, and photographs. By using animation as the source, we can produce new animations that are expressive, exaggerated or nonrealistic.
Dynapack: SpaceTime compression of the 3D animations of triangle meshes with fixed connectivity
 ACM Symp. Computer Animation
, 2003
"... Lengyel) contains 400 frames of the same connectivity, each having 41 components with a total of 5664 triangles and 3030 vertices. Dynapack quantizes the floating point coordinates of the vertices to 13 (respectively 11, and 7) bits, shown in rows 2 (respectively 3, and 5). It compresses them down t ..."
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Cited by 62 (1 self)
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Lengyel) contains 400 frames of the same connectivity, each having 41 components with a total of 5664 triangles and 3030 vertices. Dynapack quantizes the floating point coordinates of the vertices to 13 (respectively 11, and 7) bits, shown in rows 2 (respectively 3, and 5). It compresses them down to 2.91 (respectively 2.35, and 1.37) bits, resulting in a worstcase geometric error of 0.0061 (respectively 0.024, and 0.3) percent of the size of the minimum axisaligned bounding box of the animation sequence. Note that the result of the 13bit quantization is undistinguishable from the original and yields an 11to1 compression ratio over the floatingpoint representation with a 42.1 dB signaltonoise ratio. Dynapack exploits spacetime coherence to compress the