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134
Optimizing cubature for efficient integration of subspace deformations
 ACM Transactions on Graphics (SIGGRAPH Asia
, 2008
"... We propose an efficient scheme for evaluating nonlinear subspace forces (and Jacobians) associated with subspace deformations. The core problem we address is efficient integration of the subspace force density over the 3D spatial domain. Similar to Gaussian quadrature schemes that efficiently integr ..."
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Cited by 32 (5 self)
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We propose an efficient scheme for evaluating nonlinear subspace forces (and Jacobians) associated with subspace deformations. The core problem we address is efficient integration of the subspace force density over the 3D spatial domain. Similar to Gaussian quadrature schemes that efficiently integrate functions that lie in particular polynomial subspaces, we propose cubature schemes (multidimensional quadrature) optimized for efficient integration of force densities associated with particular subspace deformations, particular materials, and particular geometric domains. We support generic subspace deformation kinematics, and nonlinear hyperelastic materials. For an rdimensional deformation subspace with O(r) cubature points, our method is able to evaluate subspace forces at O(r2) cost. We also describe composite cubature rules for runtime error estimation. Results are provided for various subspace deformation models, several hyperelastic materials (St.VenantKirchhoff, MooneyRivlin, ArrudaBoyce), and multimodal (graphics, haptics, sound) applications. We show dramatically better efficiency than traditional Monte Carlo integration.
Realtime data driven deformation using kernel canonical correlation analysis
 In ACM SIGGRAPH 2008 papers
, 2008
"... Achieving intuitive control of animated surface deformation while observing a specific style is an important but challenging task in computer graphics. Solutions to this task can find many applications in datadriven skin animation, computer puppetry, and computer games. In this paper, we present an ..."
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Cited by 30 (4 self)
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Achieving intuitive control of animated surface deformation while observing a specific style is an important but challenging task in computer graphics. Solutions to this task can find many applications in datadriven skin animation, computer puppetry, and computer games. In this paper, we present an intuitive and powerful animation interface to simultaneously control the deformation of a large number of local regions on a deformable surface with a minimal number of control points. Our method learns suitable deformation subspaces from training examples, and generate new deformations on the fly according to the movements of the control points. Our contributions include a novel deformation regression method based on kernel Canonical Correlation Analysis (CCA) and a Poissonbased translation solving technique for easy and fast deformation control based on examples. Our runtime algorithm can be implemented on GPUs and can achieve a few hundred frames per second even for large datasets with hundreds of training examples.
Range scan registration using reduced deformable models
 EG
, 2009
"... We present an unsupervised method for registering range scans of deforming, articulated shapes. The key idea is to model the motion of the underlying object using a reduced deformable model. We use a linear skinning model for its simplicity and represent the weight functions on a regular grid locali ..."
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Cited by 30 (1 self)
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We present an unsupervised method for registering range scans of deforming, articulated shapes. The key idea is to model the motion of the underlying object using a reduced deformable model. We use a linear skinning model for its simplicity and represent the weight functions on a regular grid localized to the surface geometry. This decouples the deformation model from the surface representation and allows us to deal with the severe occlusion and missing data that is inherent in range scan data. We formulate the registration problem using an objective function that enforces close alignment of the 3D data and includes an intuitive notion of joints. This leads to an optimization problem that we solve using an efficient EMtype algorithm. With our algorithm we obtain smooth deformations that accurately register pairs of range scans with significant motion and occlusion. The main advantages of our approach are that it does not require user specified markers, a template, nor manual segmentation of the surface geometry into rigid parts.
FreeForm Motion Processing
 ACM TRANS. GRAPH
, 2008
"... Motion is the center of attention in many applications of computer graphics. Skeletal motion for articulated characters can be processed and altered in a great variety of ways to increase the versatility of each motion clip. However, analogous techniques have not yet been developed for freeform def ..."
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Cited by 28 (0 self)
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Motion is the center of attention in many applications of computer graphics. Skeletal motion for articulated characters can be processed and altered in a great variety of ways to increase the versatility of each motion clip. However, analogous techniques have not yet been developed for freeform deforming surfaces like cloth and faces. Given the time consuming nature of producing each freeform motion clip, the ability to alter and reuse freeform motion would be very desirable. We present a novel method for processing freeform motion that opens up a broad range of possible motion alterations, including motion blending, keyframe insertion, and temporal signal processing. Our method is based on a simple, yet powerful, differential surface representation that is invariant under rotation and translation, and which is well suited for surface editing in both space and time.
GUIBAS L.: An optimization approach for extracting and encoding consistent maps in a shape collection
 TOG
"... We introduce a novel approach for computing high quality pointtopoint maps among a collection of related shapes. The proposed approach takes as input a sparse set of imperfect initial maps between pairs of shapes and builds a compact data structure which implicitly encodes an improved set of maps b ..."
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Cited by 24 (6 self)
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We introduce a novel approach for computing high quality pointtopoint maps among a collection of related shapes. The proposed approach takes as input a sparse set of imperfect initial maps between pairs of shapes and builds a compact data structure which implicitly encodes an improved set of maps between all pairs of shapes. These maps align well with point correspondences selected from initial maps; they map neighboring points to neighboring points; and they provide cycleconsistency, so that map compositions along cycles approximate the identity map. The proposed approach is motivated by the fact that a complete set of maps between all pairs of shapes that admits nearly perfect cycleconsistency are highly redundant and can be represented by compositions of maps through a single base shape. In general, multiple base shapes are needed to adequately cover a diverse collection. Our algorithm sequentially extracts such a small collection of base shapes and creates correspondences from each of these base shapes to all other shapes. These correspondences are found by global optimization on candidate correspondences obtained by diffusing initial maps. These are then used to create a compact graphical data structure from which globally optimal cycleconsistent maps can be extracted using simple graph algorithms. Experimental results on benchmark datasets show that the proposed approach yields significantly better results than stateoftheart datadriven shape matching methods.
Segmenting a Deforming Mesh into NearRigid Components
 THE VISUAL COMPUTER
"... Given a deforming mesh in an animation, we propose a new method to segment this mesh into several nearrigid submeshes. From this deforming mesh over all frames of an animation, we can analyze the degree of deformation between two nearby faces on the mesh. Then, our algorithm partitions the given ..."
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Cited by 24 (2 self)
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Given a deforming mesh in an animation, we propose a new method to segment this mesh into several nearrigid submeshes. From this deforming mesh over all frames of an animation, we can analyze the degree of deformation between two nearby faces on the mesh. Then, our algorithm partitions the given deforming mesh into nearrigid components where the segmentation boundaries always pass at regions of large deformation. As a result, the mesh segmentation is invariant to all frames of the given animation and the motion of faces in each nearrigidcomponent can be represented by the same approximate affine transformation. To demonstrate the usefulness of the algorithm, we solve the restriction of deformation transfer for triangle meshes [30] which requires similar reference poses between source mesh and target mesh.
Animation space: A truly linear framework for character animation
 ACM Trans. Graph
, 2006
"... Skeletal subspace deformation (SSD), a simple method of character animation used in many applications, has several shortcomings; the bestknown is that joints tend to collapse when bent. We present animation space, a generalization of SSD that greatly reduces these effects and effectively eliminates ..."
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Cited by 24 (4 self)
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Skeletal subspace deformation (SSD), a simple method of character animation used in many applications, has several shortcomings; the bestknown is that joints tend to collapse when bent. We present animation space, a generalization of SSD that greatly reduces these effects and effectively eliminates them for joints that do not have an unusually large range of motion. While other, more expensive generalizations exist, ours is unique in expressing the animation process as a simple linear transformation of the input coordinates. We show that linearity can be used to derive a measure of average distance (across the space of poses), and apply this to improving parametrizations. Linearity also makes it possible to fit a model to a set of examples using leastsquares methods. The extra generality in animation space allows for a good fit to realistic data, and overfitting can be controlled to allow fitted models to generalize to new poses. Despite the extra vertex attributes, it is possible to render these animationspace models in hardware with no loss of performance relative to SSD.
Videobased Reconstruction of Animatable Human Characters
 TO APPEAR IN THE ACM SIGGRAPH ASIA CONFERENCE PROCEEDINGS
"... We present a new performance capture approach that incorporates a physicallybased cloth model to reconstruct a rigged fullyanimatable virtual double of a real person in loose apparel from multiview video recordings. Our algorithm only requires a minimum of manual interaction. Without the use of o ..."
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Cited by 24 (4 self)
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We present a new performance capture approach that incorporates a physicallybased cloth model to reconstruct a rigged fullyanimatable virtual double of a real person in loose apparel from multiview video recordings. Our algorithm only requires a minimum of manual interaction. Without the use of optical markers in the scene, our algorithm first reconstructs skeleton motion and detailed timevarying surface geometry of a real person from a reference video sequence. These captured reference performance data are then analyzed to automatically identify nonrigidly deforming pieces of apparel on the animated geometry. For each piece of apparel, parameters of a physicallybased realtime cloth simulation model are estimated, and surface geometry of occluded body regions is approximated. The reconstructed character model comprises a skeletonbased representation for the actual body parts and a physicallybased simulation model for the apparel. In contrast to previous performance capture methods, we can now also create new realtime animations of actors captured in general apparel.
Editing Arbitrarily Deforming Surface Animations
 TO APPEAR IN SIGGRAPH
, 2006
"... Deforming surfaces, such as cloth, can be generated through physical simulation, morphing, and even video capture. Such data is currently very difficult to alter after the generation process is complete, and data generated for one purpose generally cannot be adapted to other uses. Such adaptation ..."
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Cited by 23 (1 self)
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Deforming surfaces, such as cloth, can be generated through physical simulation, morphing, and even video capture. Such data is currently very difficult to alter after the generation process is complete, and data generated for one purpose generally cannot be adapted to other uses. Such adaptation would be extremely useful, however. Being able to take cloth captured from a flapping flag and attach it to a character to make a cape, or enhance the wrinkles on a simulated garment, would greatly enhance the usability and reusability of deforming surface data. In addition, it is often necessary to cleanup or “tweak ” simulation results. Doing this by editing each frame individually is a very time consuming and tedious process. Extensive research has investigated how to edit and reuse skeletal motion capture data, but very little has addressed completely nonrigid deforming surfaces. We have developed a novel method that now makes it easy to edit such arbitrary deforming surfaces. Our system enables global signal processing, direct manipulation, multiresolution embossing, and constraint editing on arbitrarily deforming surfaces, such as simulated cloth, motioncaptured cloth, morphs, and other animations. The foundation of our method is a novel timevarying multiresolution transform, which adapts to the changing geometry of the surface in a temporally coherent manner.