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70
Timewarp rigid body simulation
 IN PROC. OF ACM SIGGRAPH
, 2000
"... The traditional highlevel algorithms for rigid body simulation work well for moderate numbers of bodies but scale poorly to systems of hundreds or more moving, interacting bodies. The problem is unnecessary synchronization implicit in these methods. Jefferson´s timewarp algorithm (Jefferson 85) is ..."
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Cited by 64 (0 self)
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The traditional highlevel algorithms for rigid body simulation work well for moderate numbers of bodies but scale poorly to systems of hundreds or more moving, interacting bodies. The problem is unnecessary synchronization implicit in these methods. Jefferson´s timewarp algorithm (Jefferson 85) is a technique for alleviating this problem in parallel discrete event simulation. Rigid body dynamics, though a continuous process, exhibits many aspects of a discrete one. With modification, the timewarp algorithm can be used in a uniprocessor rigid body simulator to give substantial performance improvements for simulations with large numbers of bodies. This paper describes the limitations of the traditional highlevel simulation algorithms, introduces Jefferson´s algorithm, and extends and optimizes it for the rigid body case. It addresses issues particular to rigid body simulation, such as collision detection and contact group management, and describes how to incorporate these into the timewarp framework. Quantitative experimental results indicate that the timewarp algorithm offers significant performance improvements over traditional highlevel rigid body simulation algorithms, when applied to systems with hundreds of bodies. It also helps pave the way to parallel implementations, as the paper discusses.
Fast and Simple 2D Geometric Proximity Queries Using Graphics Hardware
, 2001
"... We present a new approach for computing generalized proximity information of arbitrary 2D objects using graphics hardware. Using multipass rendering techniques and accelerated distance computation, our algorithm performs proximity queries not only for detecting collisions, but also for computing in ..."
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Cited by 62 (10 self)
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We present a new approach for computing generalized proximity information of arbitrary 2D objects using graphics hardware. Using multipass rendering techniques and accelerated distance computation, our algorithm performs proximity queries not only for detecting collisions, but also for computing intersections, separation distance, penetration depth, and contact points and normals. Our hybrid geometry and imagebased approach balances computation between the CPU and graphics subsystems. Geometric objectspace techniques coarsely localize potential intersection regions or closest features between two objects, and imagespace techniques compute the lowlevel proximity information in these regions. Most of the proximity information is derived from a distance field computed using graphics hardware. We demonstrate the performance in collision response computation for rigid and deformable body dynamics simulations. Our approach provides proximity information at interactive rates for a variet...
Strategies for Polyhedral Surface Decomposition: An Experimental Study
, 1995
"... This paper addresses the problem of decomposing a complex polyhedral surface into a small number of "convex" patches (ie, boundary parts of convex polyhedra). The corresponding optimization problem is shown to be NPcomplete and an experimental search for good heuristics is undertaken. 1 I ..."
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Cited by 60 (5 self)
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This paper addresses the problem of decomposing a complex polyhedral surface into a small number of "convex" patches (ie, boundary parts of convex polyhedra). The corresponding optimization problem is shown to be NPcomplete and an experimental search for good heuristics is undertaken. 1 Introduction Convex shapes are easiest to represent, manipulate, and render. Even though they form the building blocks of bottomup solid modelers, it is more often the case that the convex structure of a geometric shape is lost in its representation. We are then presented, not with the solidmodeling problem of putting together primitive convex objects, but with the reverse problem of extracting convexity out of a complex shape. The classical example is that of cutting up a 3polyhedron into convex pieces. This is often a useful, sometimes a required, preprocessing step in graphics, manufacturing, and mesh generation. The problem has been exhaustively researched in the last few years [2][18]. Despi...
RECODE: An ImageBased Collision Detection Algorithm
 Proceedings of Pacific Graphics ’98
, 1998
"... Object interactions are ubiquitous in interactive computer graphics, 3D object motion simulations, virtual reality and robotics applications. Most collision detection algorithms are based on geometrical object–space interference tests. Some algorithms have employed an image– space approach to the co ..."
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Cited by 38 (0 self)
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Object interactions are ubiquitous in interactive computer graphics, 3D object motion simulations, virtual reality and robotics applications. Most collision detection algorithms are based on geometrical object–space interference tests. Some algorithms have employed an image– space approach to the collision detection problem. In this article, we demonstrate an image–space collision detection process that allows substatial computational savings during the image–space interference test. This approach makes efficient use of the graphics rendering hardware for real–time complex object interactions.
Collision prediction for polyhedra under screw motions
 ACM Symposium in Solid Modeling and Applications
, 2003
"... The prediction of collisions amongst N rigid objects may be reduced to a series of computations of the time to first contact for all pairs of objects. Simple enclosing bounds and hierarchical partitions of the spacetime domain are often used to avoid testing objectpairs that clearly will not colli ..."
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Cited by 29 (3 self)
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The prediction of collisions amongst N rigid objects may be reduced to a series of computations of the time to first contact for all pairs of objects. Simple enclosing bounds and hierarchical partitions of the spacetime domain are often used to avoid testing objectpairs that clearly will not collide. When the remaining pairs involve only polyhedra under straightline translation, the exact computation of the collision time and of the contacts requires only solving for intersections between linear geometries. When a pair is subject to a more general relative motion, such a direct collision prediction calculation may be intractable. The popular brute force collision detection strategy of executing the motion for a series of small time steps and of checking for static interferences after each step is often computationally prohibitive. We propose instead a less expensive collision prediction strategy, where we approximate the relative motion between pairs of objects by a sequence of screw motion segments, each defined by the relative position and orientation of the two objects at the beginning and at the end of the segment. We reduce the computation of the exact collision time and of the corresponding face/vertex and edge/edge collision points to the numeric extraction of the roots of simple univariate analytic functions. Furthermore, we propose a series of simple rejection tests, which exploit the particularity of the screw motion to immediately decide that some objects do not collide or to speedup the prediction of collisions by about 30%, avoiding on average 3/4 of the rootfinding queries even when the object actually collide.
Computation of solid–liquid phase fronts in the sharp interface limit on fixed grids
 J. Comput. Phys
, 1999
"... A finitedifference formulation is applied to track solid–liquid boundaries on a fixed underlying grid. The interface is not of finite thickness but is treated as a discontinuity and is explicitly tracked. The imposition of boundary conditions exactly on a sharp interface that passes through the Ca ..."
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Cited by 29 (2 self)
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A finitedifference formulation is applied to track solid–liquid boundaries on a fixed underlying grid. The interface is not of finite thickness but is treated as a discontinuity and is explicitly tracked. The imposition of boundary conditions exactly on a sharp interface that passes through the Cartesian grid is performed using simple stencil readjustments in the vicinity of the interface. Attention is paid to formulating difference schemes that are globally secondorder accurate in x and t. Error analysis and grid refinement studies are performed for test problems involving the diffusion and convection–diffusion equations, and for stable solidification problems. Issues concerned with stability and change of phase of grid points in the evolution of solid–liquid phase fronts are also addressed. It is demonstrated that the field calculation is secondorder accurate while the position of the phase front is calculated to firstorder accuracy. Furthermore, the accuracy estimates hold for the cases where there is a property jump across the interface. Unstable solidification phenomena are simulated and an attempt is made to compare results with previously published work. The results indicate the need to begin an effort to benchmark computations of instability phenomena. c ° 1999 Academic Press
Rigid body simulation
 SIGGRAPH 95 Course Note 34. ACM SIGGRAPH
, 1992
"... Please note: This document is ©2001 by David Baraff. This chapter may be freely duplicated and distributed so long as no consideration is received in return, and this copyright notice remains intact. ..."
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Cited by 28 (0 self)
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Please note: This document is ©2001 by David Baraff. This chapter may be freely duplicated and distributed so long as no consideration is received in return, and this copyright notice remains intact.
Interactive occlusion and automatic object placement for augmented reality
 In Computer Graphics Forum
, 1996
"... ..."
Normal Bounds for SubdivisionSurface Interference Detection
 In Proc. of IEEE Scientific Visualization, IEEE
, 2001
"... Subdivision surfaces are an attractive representation when modeling arbitrary topology freeform surfaces and show great promise for applications in engineering design [5, 6] and computer animation [10]. Interference detection is a critical tool in many of these applications. In this paper we derive ..."
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Cited by 26 (2 self)
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Subdivision surfaces are an attractive representation when modeling arbitrary topology freeform surfaces and show great promise for applications in engineering design [5, 6] and computer animation [10]. Interference detection is a critical tool in many of these applications. In this paper we derive normal bounds for subdivision surfaces and use these to develop an efficient algorithm for (self) interference detection.
Rapid and Accurate Contact Determination between Spline Models using ShellTrees
, 1998
"... In this paper, we present an efficient algorithm for contact determination between spline models. We make use of a new hierarchy, called ShellTree, that comprises of spherical shells and oriented bounding boxes. Each spherical shell corresponds to a portion of the volume between two concentric spher ..."
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Cited by 25 (4 self)
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In this paper, we present an efficient algorithm for contact determination between spline models. We make use of a new hierarchy, called ShellTree, that comprises of spherical shells and oriented bounding boxes. Each spherical shell corresponds to a portion of the volume between two concentric spheres. Given large spline models, our algorithm decomposes each surface into Bezier patches as part of preprocessing. At runtime it dynamically computes a tight fitting axisaligned bounding box across each Bezier patch and efficiently checks all such boxes for overlap. Using offline and online techniques for tree construction, our algorithm computes ShellTrees for Bezier patches and performs fast overlap tests between them to detect collisions. The overall approach can trade off runtime performance for reduced memory requirements. We have implemented the algorithm and tested itonlarge models, each composed of hundred ofpatches. Its performance varies with the configurations of the objects. For many complex models composed of hundreds of patches, it can accurately compute the contacts in a few milliseconds.