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14
Physically Based Deformable Models in Computer Graphics
 EUROGRAPHICS 2005 STAR – STATE OF THE ART REPORT
, 2005
"... Physically based deformable models have been widely embraced by the Computer Graphics community. Many problems outlined in a previous survey by Gibson and Mirtich [GM97] have been addressed, thereby making these models interesting and useful for both offline and realtime applications, such as motio ..."
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Cited by 167 (3 self)
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Physically based deformable models have been widely embraced by the Computer Graphics community. Many problems outlined in a previous survey by Gibson and Mirtich [GM97] have been addressed, thereby making these models interesting and useful for both offline and realtime applications, such as motion pictures and video games. In this paper, we present the most significant contributions of the past decade, which produce such impressive and perceivably realistic animations and simulations: finite element/difference/volume methods, massspring systems, meshfree methods, coupled particle systems and reduced deformable models based on modal analysis. For completeness, we also make a connection to the simulation of other continua, such as fluids, gases and melting objects. Since time integration is inherent to all simulated phenomena, the general notion of time discretization is treated separately, while specifics are left to the respective models. Finally, we discuss areas of application, such as elastoplastic deformation and fracture, cloth and hair animation, virtual surgery simulation, interactive entertainment and fluid/smoke animation, and also suggest areas for future research.
M.: Contact Handling for Deformable PointBased Objects
 In: Proceedings of the Vision, Modeling, and Visualization Conference (VMV
, 2004
"... This paper presents an approach to collision detection and response for dynamically deforming pointbased objects. Both the volume of an object and its surface are represented by point sets. In case of a collision, response forces are computed for penetrating surface points and distributed to volu ..."
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Cited by 23 (6 self)
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This paper presents an approach to collision detection and response for dynamically deforming pointbased objects. Both the volume of an object and its surface are represented by point sets. In case of a collision, response forces are computed for penetrating surface points and distributed to volume points which are used for simulating the object dynamics. The decoupling of collision handling and deformation allows for a very stable collision response while maintaining interactive update rates of the dynamic simulation for environments with moderate complexity. Simulation results are presented for elastically and plastically deforming objects with changing topology. 1
Covering Minkowski sum boundary using points . . .
 COMPUTER AIDED GEOMETRIC DESIGN
, 2008
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AN EFFICIENT COLLISION DETECTION ALGORITHM FOR POINT CLOUD MODELS
"... Point clouds models are a common shape representation for several reasons. Threedimensional scanning devices are widely used nowadays and points are an attractive primitive for rendering complex geometry. Nevertheless, there is not much literature on collision detection for point cloud models. This ..."
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Cited by 1 (1 self)
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Point clouds models are a common shape representation for several reasons. Threedimensional scanning devices are widely used nowadays and points are an attractive primitive for rendering complex geometry. Nevertheless, there is not much literature on collision detection for point cloud models. This paper presents a novel collision detection algorithm for point cloud models. The scene graph is divided in voxels. The objects of each voxel are organized in Rtrees hierarchies of AxisAligned Bounding Boxes to group neighboring points and filter out very quickly parts of objects that do not interact with other models. The proposed algorithm also uses Overlapping AxisAligned Bounding Boxes to improve the performance of the collision detection process. Points derived from laser scanned data typically are not segmented and can have arbitrary spatial resolution thus introducing computational and modeling issues. We address these issues and results show that the proposed collision detection algorithm effectively finds intersections between point cloud models since it is able to reduce the number of bounding volume checks and updates.
Interpolation Search for Point Cloud Intersection
"... We present a novel algorithm to compute intersections of two point clouds. It can be used to detect collisions between implicit surfaces defined by two point sets, or to construct their intersection curves. Our approach utilizes a proximity graph that allows for quick interpolation search of a commo ..."
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We present a novel algorithm to compute intersections of two point clouds. It can be used to detect collisions between implicit surfaces defined by two point sets, or to construct their intersection curves. Our approach utilizes a proximity graph that allows for quick interpolation search of a common zero of the two implicit functions. First, pairs of points from one point set are constructed, bracketing the intersection with the other surface. Second, an interpolation search along shortest paths in the graph is performed. Third, the solutions are refined. For the first and third step, randomized sampling is utilized. We show that the number of evaluations of the implicit function and the overall runtime is in O(loglogN) in the average case, where N is the point cloud size. The storage is bounded by O(N). Our measurements show that we achieve a speedup by an order of magnitude compared to a recently proposed randomized sampling technique for point cloud collision detection. Keywords: Collision detection, weighted least squares, proximity graphs, implicit surfaces.
Collision Detection on Point Clouds Using a 2.5+D ImageBased Approach
"... This work explores an alternative approach to the problem of collision detection using images instead of geometry to represent complex polygonal environments and buildings derived from laser scan data, used in an interactive navigation scenario. In a preprocessing step, models that are not point clo ..."
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This work explores an alternative approach to the problem of collision detection using images instead of geometry to represent complex polygonal environments and buildings derived from laser scan data, used in an interactive navigation scenario. In a preprocessing step, models that are not point clouds, are sampled to create representative point clouds. Our algorithm then creates several 2.5+D maps in a given volume that stacked together form a 3D section of the world. We show that our new representation allows for realistic and fast collision queries with complex geometry such as stairs and that the algorithm is insensitive to the size of the input point cloud at runtime.
Approved by:
, 2013
"... ii JIA PAN: Efficient Configuration Space Construction and Optimization (Under the direction of Dinesh Manocha) The configuration space is a fundamental concept that is widely used in algorithmic robotics. Many applications in robotics, computeraided design, and related areas can be reduced to com ..."
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ii JIA PAN: Efficient Configuration Space Construction and Optimization (Under the direction of Dinesh Manocha) The configuration space is a fundamental concept that is widely used in algorithmic robotics. Many applications in robotics, computeraided design, and related areas can be reduced to computational problems in terms of configuration spaces. In this dissertation, we address three main computational challenges related to configuration spaces: 1) how to efficiently compute an approximate representation of highdimensional configuration spaces; 2) how to efficiently perform geometric, proximity, and motion planning queries in highdimensional configuration spaces; and 3) how to model uncertainty in configuration spaces represented by noisy sensor data. We present new configuration space construction algorithms based on machine learning and geometric approximation techniques. These algorithms perform collision queries on many configuration samples. The collision query results are used to compute an approximate representation for the configuration space, which quickly converges to the exact configuration space. We highlight the efficiency of our algorithms for penetration depth computation and instancebased motion planning. We also present parallel GPUbased algorithms to accelerate the performance of optimization and search computations in configuration spaces. In particular, we design efficient GPUbased parallel knearest neighbor and parallel collision detection algorithms and use these algorithms to accelerate motion planning. In order to extend configuration space algorithms to handle noisy sensor data arising from realworld robotics applications, we model the uncertainty in the configuration space by formulating the collision probabilities for noisy data. We use these algorithms to perform reliable motion planning for the PR2 robot. iii To Inspector Gadget. iv
AUTOMATIC COLLISION FREE PATH PLANNING IN HYBRID TRIANGLE AND POINT MODELS: A CASE STUDY
"... Collision free path planning is a key technology for assembly analysis, robot line optimization, and virtual assessment of industrial maintenance and service. The ability to compute collision free paths relies on the ability to quickly and robustly query the proximity of the planning object to its s ..."
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Collision free path planning is a key technology for assembly analysis, robot line optimization, and virtual assessment of industrial maintenance and service. The ability to compute collision free paths relies on the ability to quickly and robustly query the proximity of the planning object to its surroundings. Path planning with triangulated models is a well studied problem, however, hybrid models comprising both points and triangles present new and difficult challenges. Working directly with point clouds is becoming more relevant because it allows one to scan existing industrial installations and path plan with the scan data instead of possibly incorrect planned layouts. In this paper we implement and analyze a new hybrid path planning interface on a case study in robot line manufacturing and demonstrate its feasibility in comparison to an existing CAD model of the work environment and show that triangulating the original point cloud is undesirable for path planning. 1
KEY WORDS: Collision Detection, KD Tree, Kinematic Laser Scanning, 3D Point Clouds
"... Measuring the structure gauge of tunnels and other narrow passages has so far been the only way to evaluate whether large vehicles can pass through them. But especially for very long vehicles like train wagons and their cargo, the structure gauge is an insufficient measure because the center part of ..."
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Measuring the structure gauge of tunnels and other narrow passages has so far been the only way to evaluate whether large vehicles can pass through them. But especially for very long vehicles like train wagons and their cargo, the structure gauge is an insufficient measure because the center part of the vehicle between two bogies will inevitably leave the swept volume of its cross section when moving along any other trajectory than a straight line perpendicular to its cross section. In addition, the vehicle as well as the cargo must keep a minimum safety margin from the environment at all points of its trajectory. This paper explores an automated method to check for possible collisions of a model represented by a 3D point cloud moving through the 3D point cloud of an environment. We were given environment data of a train track through a narrow tunnel where simply relying on the structure gauge would indicate that a given wagon would pass through without any collision even though in reality, the train wagon would collide with the inner tunnel wall inside a sharp turn of the tracks. The kd tree based collision detection method presented in this paper is able to correctly highlight these collisions and indicate the penetration depth of each colliding point of the environment into the model of the train wagon. It can be generalized for any setup where two static point clouds have to be tested for intersection along a trajectory. 1.
Abstract
"... This paper addresses a novel translation method based on Hidden Markov Model using template rules after learning them from the bilingual corpus. The method can enhance the translation accuracy and ensure a low complexity in comparing with the pervious template learning translation method and draws a ..."
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This paper addresses a novel translation method based on Hidden Markov Model using template rules after learning them from the bilingual corpus. The method can enhance the translation accuracy and ensure a low complexity in comparing with the pervious template learning translation method and draws a new perspective for applying statistical machine learning on example based translations. domain. Keywords: Machine translation, EBMT, Template learning translation, HMM. 1