Results 11  20
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127
Continuous collision detection for two moving elliptic disks
 IEEE Trans. Robotics
, 2006
"... Abstract—Collision detection and avoidance are important in robotics. Compared with commonly used circular disks, elliptic disks provide a more compact shape representation for robots or other vehicles confined to move in the plane. Furthermore, elliptic disks allow a simpler analytic representation ..."
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Abstract—Collision detection and avoidance are important in robotics. Compared with commonly used circular disks, elliptic disks provide a more compact shape representation for robots or other vehicles confined to move in the plane. Furthermore, elliptic disks allow a simpler analytic representation than rectangular boxes, which makes it easier to perform continuous collision detection (CCD). We shall present a fast and accurate method for CCD between two moving elliptic disks, which avoids any need to sample the time domain of the motion, thus avoiding the possibility of missing collisions between time samples. Based on some new algebraic conditions on the separation of two ellipses, we reduce collision detection for two moving ellipses to the problem of detecting real roots of a univariate equation, which is the discriminant of the characteristic polynomial of the two ellipses. Several techniques are investigated for robust and accurate processing of this univariate equation for two classes of commonly used motions: planar cycloidal motions and planar rational motions. Experimental results demonstrate the efficiency, accuracy, and robustness of our method. Index Terms—Collision detection, ellipses, elliptic disks, interference analysis, rational motion. I.
FALCIDIENO B.: Hierarchical convex approximation for fast region selection
 Computer Graphics Forum
"... Given a 3D solid model S represented by a tetrahedral mesh, we describe a novel algorithm to compute a hierarchy of convex polyhedra that tightly enclose S. The hierarchy can be browsed at interactive speed on a modern PC and it is useful for implementing an intuitive feature selection paradigm for ..."
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Given a 3D solid model S represented by a tetrahedral mesh, we describe a novel algorithm to compute a hierarchy of convex polyhedra that tightly enclose S. The hierarchy can be browsed at interactive speed on a modern PC and it is useful for implementing an intuitive feature selection paradigm for 3D editing environments. Convex parts often coincide with perceptually relevant shape components and, for their identification, existing methods rely on the boundary surface only. In contrast, we show that the notion of part concavity can be expressed and implemented more intuitively and efficiently by exploiting a tetrahedrization of the shape volume. The method proposed is completely automatic, and generates a tree of convex polyhedra in which the root is the convex hull of the whole shape, and the leaves are the tetrahedra of the input mesh. The algorithm proceeds bottomup by hierarchically clustering tetrahedra into nearly convex aggregations, and the whole process is significantly fast. We prove that, in the average case, for a mesh of n tetrahedra O(nlog 2 n) operations are sufficient to compute the whole tree. 1.
Efficient Collision Detection Among Moving Spheres with Unknown Trajectories
 Algorithmica
, 2005
"... Abstract. Collision detection is critical for applications that demand a great deal of spatial interaction among objects. In such applications the trajectory of an object is often not known in advance either since a user is allowed to move an object at his/her will, or since an object moves under th ..."
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Cited by 9 (0 self)
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Abstract. Collision detection is critical for applications that demand a great deal of spatial interaction among objects. In such applications the trajectory of an object is often not known in advance either since a user is allowed to move an object at his/her will, or since an object moves under the rules that are hard to describe by exact mathematical formulas. In this paper we present a new algorithm that efficiently detects the collisions among moving spheres with unknown trajectories. We assume that the current position and velocity of every sphere can be probed at any time although its trajectory is unknown. We also assume that the magnitude of the acceleration of each sphere is bounded. Under these assumptions, we represent the bounding volume of the sphere as a moving sphere of variable radius, called a timevarying bound. Whenever the timevarying bounds of two spheres collide with each other, they are checked for actual collision. Exploiting these bounds, the previous eventdriven approach for detecting the collisions among multiple moving spheres with ballistic trajectories is generalized for those with unknown trajectories. The proposed algorithm shows an interactive performance for thousands of moving spheres with unknown trajectories without any hardware help.
Interactive Collision Detection for Deformable Models using Streaming AABBs
 IEEE TVCG
"... We present an interactive and accurate collision detection algorithm for deformable, polygonal objects based on the streaming computational model. Our algorithm can detect all possible pairwise primitivelevel intersections between two severely deforming models at highly interactive rates. In our s ..."
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Cited by 9 (0 self)
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We present an interactive and accurate collision detection algorithm for deformable, polygonal objects based on the streaming computational model. Our algorithm can detect all possible pairwise primitivelevel intersections between two severely deforming models at highly interactive rates. In our streaming computational model, we consider a set of axis aligned bounding boxes (AABBs) that bound each of the given deformable objects as an input stream and perform massivelyparallel pairwise, overlapping tests onto the incoming streams. As a result, we are able to prevent performance stalls in the streaming pipeline that can be caused by expensive indexing mechanism required by bounding volume hierarchybased streaming algorithms. At runtime, as the underlying models deform over time, we employ a novel, streaming algorithm to update the geometric changes in the AABB streams. Moreover, in order to get only the computed result (i.e., collision results between AABBs) without reading back the entire output streams, we propose a streaming en/decoding strategy that can be performed in a hierarchical fashion. After determining overlapped AABBs, we perform a primitivelevel (e.g., triangle) intersection checking on a serial computational model such as CPUs. We implemented the entire pipeline of our algorithm using offtheshelf graphics processors (GPUs), such as nVIDIA GeForce 7800 GTX, for streaming computations, and Intel Dual Core 3.4G processors for serial computations. We benchmarked our algorithm with different models of varying complexities, ranging from 15K up to 50K triangles, under various deformation motions, and the timings were obtained as 30∼100 FPS depending on the complexity of models and their relative configurations. Finally, we made comparisons with a wellknown GPUbased collision detection algorithm, CULLIDE [4] and observed about three times performance improvement over the earlier approach. We also made comparisons with a SWbased AABB culling algorithm [2] and observed about two times improvement.
Algorithm and data structures for efficient energy maintenance during Monte Carlo simulation of proteins
 Journal of Computational Biology
, 2004
"... Monte Carlo simulation (MCS) is a common methodology to compute pathways and thermodynamic properties of proteins. A simulation run is a series of random steps in conformation space, each perturbing some degrees of freedom of the molecule. A step is accepted with a probability that depends on the c ..."
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Cited by 9 (2 self)
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Monte Carlo simulation (MCS) is a common methodology to compute pathways and thermodynamic properties of proteins. A simulation run is a series of random steps in conformation space, each perturbing some degrees of freedom of the molecule. A step is accepted with a probability that depends on the change in value of an energy function. Typical energy functions sum many terms. The most costly ones to compute are contributed by atom pairs closer than some cutoff distance. This paper introduces a new method that speeds up MCS by exploiting the facts that proteins are long kinematic chains and that few degrees of freedom are changed at each step. A novel data structure, called the ChainTree, captures both the kinematics and the shape of a protein at successive levels of detail. It is used to efficiently detect selfcollision (steric clash between atoms) and/or find all atom pairs contributing to the energy. It also makes it possible to identify partial energy sums left unchanged by a perturbation, thus allowing the energy value to be incrementally updated. Computational tests on four proteins of sizes ranging from 68 to 755 amino acids show that MCS with the ChainTree method is significantly faster (as much as 10 times faster for the largest protein) than with the widely used grid method. They also indicate that speedup increases with larger proteins.
Proximity queries between convex objects: An interior point approach for implicit surfaces
 IN 2006 IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND AUTOMATION
, 2006
"... This paper presents an interior point approach to exact distance computation between convex objects represented as intersections of implicit surfaces. Exact distance computation algorithms are particularly important for applications involving objects that make contact, such as in dynamic simulatio ..."
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Cited by 8 (1 self)
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This paper presents an interior point approach to exact distance computation between convex objects represented as intersections of implicit surfaces. Exact distance computation algorithms are particularly important for applications involving objects that make contact, such as in dynamic simulations and in contact point prediction for dextrous manipulation. They can also be used in the narrow phase of hierarchical collision detection. In contrast to geometric approaches developed for polyhedral objects, we formulate the distance computation problem as a convex optimization problem; this optimization formulation has been previously described for polyhedral objects. We demonstrate that for general convex objects represented as implicit surfaces, interior point approaches are sufficiently fast, and owing to their global convergence properties, are the only provably good choice for solving proximity query problems for some object classes. We use a primaldual interior point algorithm that solves the KKT conditions obtained from the convex programming formulation. For the case of polyhedra and quadrics, we establish a theoretical time complexity of O(n 1.5), where n is the number of constraints. We present implementation results for example implicit surface objects, including polyhedra, quadrics, and generalizations of quadrics such as superquadrics and hyperquadrics, as well as intersections of these surfaces. We demonstrate that in practice, the algorithm takes time linear in the number of constraints, and that distance computation rates of about 1 kHz can be achieved. We also extend the approach to proximity queries between deforming convex objects. Finally, we show that continuous collision detection for linearly translating objects can be performed by solving two related convex optimization problems. For polyhedra and quadrics, we establish that the computational complexity of this problem is O(n 1.5).
Fast oriented bounding box optimization on the rotation group SO(3, R)
 ACM TRANSACTIONS ON GRAPHICS
, 2011
"... An exact algorithm to compute an optimal 3D oriented bounding box was published in 1985 by Joseph O’Rourke, but it is slow and extremely hard to implement. In this article we propose a new approach, where the computation of the minimalvolume OBB is formulated as an unconstrained optimization proble ..."
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Cited by 7 (0 self)
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An exact algorithm to compute an optimal 3D oriented bounding box was published in 1985 by Joseph O’Rourke, but it is slow and extremely hard to implement. In this article we propose a new approach, where the computation of the minimalvolume OBB is formulated as an unconstrained optimization problem on the rotation group SO(3,R). It is solved using a hybrid method combining the genetic and NelderMead algorithms. This method is analyzed and then compared to the current stateoftheart techniques. It is shown to be either faster or more reliable for any accuracy.
Convex Hull Covering of Polygonal Scenes for Accurate Collision Detection in Games
"... (a) A building model used in computer games. (b) Convex hull covering computed by our algorithm. Figure 1: A result of convex hull covering. (a) A complex building mesh used in games, where front and top walls are culled to reveal the interior structures. The building contains a disconnected collect ..."
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(a) A building model used in computer games. (b) Convex hull covering computed by our algorithm. Figure 1: A result of convex hull covering. (a) A complex building mesh used in games, where front and top walls are culled to reveal the interior structures. The building contains a disconnected collection of closed and open mesh pieces with highly nonuniform tessellations. (b) The convex hulls obtained, shown in different colors, collectively cover the building geometry (they may overlap, hence a covering), but do not take away any original game playing space — this is our accuracy requirement. The original model has 14,608 polygons and the algorithm returned 3,137 convex hulls. Although the convex hull count is still high due to the strict accuracy requirement, about 80 % of collision entity reduction (triangles to convex hulls) still provides great potential to lower the computation cost of collision detection. Decomposing a complex object into simpler pieces, e.g., convex patches or convex polyhedra, is a wellstudied geometry problem. A well constructed decomposition can greatly accelerate collision detection since intersections with and between convex objects are fast to compute. In this paper, we look at a particular instance of the convex decomposition problem which arises from realworld game development. Given a collection of polyhedral surfaces (possibly
Mechanical part assembly planning with virtual mannequins
 Proceedings of IEEE International Symposium on Assembly and Task Planning
, 2005
"... This paper deals with mechanical part assembly planning. The goal is to automatically compute a collisionfree path for both the part to be assembled and the mannequin manipulating it. Two approaches are proposed according to the difficulty of the problem. Both are based on a general probabilistic ..."
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This paper deals with mechanical part assembly planning. The goal is to automatically compute a collisionfree path for both the part to be assembled and the mannequin manipulating it. Two approaches are proposed according to the difficulty of the problem. Both are based on a general probabilistic diffusion algorithm working in the configuration space of the considered system. The first approach consists in first planning a path for the part alone and then in checking the feasibility of the solution by adding the mannequin. The second one considers the part grasped and the mannequin as a single system. While the first approach performs quickly the second one is able to solve more constrained and difficult cases. Both solutions are based on the same path planning library allowing the user to easily evaluate the proposed solutions. Experimental results based on feedback experiences in automotive industry are presented. 1
DEBUNNE G.: MonteCarlo collision detection
, 2004
"... HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte p ..."
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HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et a ̀ la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.