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Incremental algorithms for collision detection between solid models
 IEEE Transactions on Visualization and Computer Graphics
, 1995
"... solid models ..."
Beyond Keyframing: An Algorithmic Approach to Animation
 Proceedings of Graphics Interface '92
, 1992
"... The use of physical system simulation has led to realistic animation of passive objects, such as sliding blocks or bouncing balls. However, complex active objects like human figures and insects need a control mechanism to direct their movements. We present a paradigm that combines the advantages of ..."
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Cited by 31 (1 self)
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The use of physical system simulation has led to realistic animation of passive objects, such as sliding blocks or bouncing balls. However, complex active objects like human figures and insects need a control mechanism to direct their movements. We present a paradigm that combines the advantages of both physical simulation and algorithmic specification of movement. The animator writes an algorithm to control the object and runs this algorithm on a physical simulator to produce the animation. Algorithms can be reused or combined to produce complex sequences of movements, eliminating the need for keyframing. We have applied this paradigm to control a biped which can walk and can climb stairs. The walking algorithm is presented along with the results from testing with the Newton simulation system.
Collision Detection and Analysis in a Physically Based Simulation
 In Eurographics Workshop on Animation and Simulation
, 1991
"... We consider the geometric support in detecting and analyzing collisions and contact between arbitrarily shaped polyhedral objects for a physically based simulation. The contact detection is formulated as a static collisiondetection problem in threedimensional space. We address both robustness and ..."
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Cited by 27 (1 self)
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We consider the geometric support in detecting and analyzing collisions and contact between arbitrarily shaped polyhedral objects for a physically based simulation. The contact detection is formulated as a static collisiondetection problem in threedimensional space. We address both robustness and efficiency of the problem, and show how both can be achieved by using the brepindex data structure. 1 Introduction A computer simulation of physical systems that is based on rigidbody dynamics and that involves objects with arbitrary shapes requires the services of a geometric modeling system. The geometric modeling system is used initially to establish mass properties and to formulate constraints for the system's dynamics. When simulating the motion of objects in the presence of obstacles with possible collisions and prolonged contact, the geometric modeling system is used throughout the simulation. The dynamics modeler must inquire at each time step whether two bodies are about to colli...
BrepIndex: A Multidimensional Space Partitioning Tree
, 1991
"... In this paper we present the Brepindex, a multidimensional space partitioning data structure that provides quick spatial access to the vertices, edges and faces of a boundary representation (Brep), thus yielding a single unified representation for polyhedral solids. We give an algorithm for the con ..."
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Cited by 20 (3 self)
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In this paper we present the Brepindex, a multidimensional space partitioning data structure that provides quick spatial access to the vertices, edges and faces of a boundary representation (Brep), thus yielding a single unified representation for polyhedral solids. We give an algorithm for the construction of the Brepindex and prove its correctness. We show that its size is \Omega\Gamma v + e + f), where v, e, and f are the number of vertices, edges, and faces of the Brep. The lower bound can be achieved for some Breps by compressing the structure using simple rewrite rules. We then demonstrate robust point and line/Brep classification methods given an implementation that uses finiteprecision arithmetic. Keywords: Classification, Brep, BSP Trees, Data Structures 1. Introduction Most data structures that exist for representing polyhedral solids can be categorized either as boundarybased or as volumebased. Each category has certain benefits not found in the other and therefore, ...
robmod: A Geometry Engine for Robotics
 In Int. Conf. Robotics & Automation
, 1988
"... Geometry will play a central role in the development of intelligent robotic systems. We describe a geometry engine, called robmod, that has been designed specifically for intelligent robotics applications. robmod is usable both as a geometric modelling system, based on the constructive solid geometr ..."
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Cited by 9 (6 self)
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Geometry will play a central role in the development of intelligent robotic systems. We describe a geometry engine, called robmod, that has been designed specifically for intelligent robotics applications. robmod is usable both as a geometric modelling system, based on the constructive solid geometry paradigm, and as a geometry engine that can be interrogated by programs that are reasoning about space. robmod is thus able to reduce the geometric sophistication required in such spatial reasoning programs. This paper originally appeared in Int. Conf. Robotics & Automation, Philadelphia, April 1988, pages 880885. c flIEEE 1988: reformatted for the WWW 1996. Contact address: Oxford University Computing Laboratory, Wolfson Building, Parks Road, Oxford OX1 3QD, UK. Phone: +44 1865 273850. Email Stephen.Cameron@comlab.ox.ac.uk 1 Introduction Geometry will play a central role in the development of intelligent robotic systems [5]. For example, collision detection and avoidance are ...
Backface Culling applied to Collision Detection of Polyhedra
 Journal of Visualization and Computer Animation
, 1994
"... this paper we show how this technique can be modified to reduce unnecessary checking of boundary elements in collision detection for a physicalbased simulation and animation systems. At each time step, we determine a priori which faces cannot be part of the contact between two polyhedra and thus can ..."
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Cited by 9 (1 self)
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this paper we show how this technique can be modified to reduce unnecessary checking of boundary elements in collision detection for a physicalbased simulation and animation systems. At each time step, we determine a priori which faces cannot be part of the contact between two polyhedra and thus can be culled. In the computer graphics technique, the normal vector of a polygon is compared with the view direction. Here, the normal is compared to one or possibly several relative velocity vectors, and the face is culled when its motion is in the opposite direction of the normal vector. We also give an algorithm that takes linear time in terms of the number of faces, and on the average eliminates half of the polygons. Due to its low computational overhead, when it is used as a front end to a collision detection system, a noticeable improvement in performance can be achieved. Keywords: culling, collision detection, animation, simulation. 1 Introduction
Animation of 3D human locomotion: Climbing stairs and descending stairs
 In Eurographics Workshop on Animation and Simulation
, 1992
"... Abstract This paper presents an intuitive, easytouse approach to controlling simulated human figures for the purpose of animation. The animator writes an algorithm to control the object and runs this algorithm on a physical simulator. The control algorithm can interact with the simulator by adding ..."
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Cited by 6 (1 self)
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Abstract This paper presents an intuitive, easytouse approach to controlling simulated human figures for the purpose of animation. The animator writes an algorithm to control the object and runs this algorithm on a physical simulator. The control algorithm can interact with the simulator by adding or removing algebraic constraints from the simulator's system of motion equations as the algorithm observes changes in the simulator's world state. For human locomotion, the use of algebraic constraints allows the algorithm to control intuitive variables, like the acceleration of the centre of mass or the sum of the forces between the human figure and the ground. We have applied this approach to control a simulated biped which can walk up and down stairs and on a level surface. The resulting animation is realistic, and the control algorithms are conceptually simple.
SoftLab  A Virtual Laboratory for Computational Science
 IN P.R. HONECK & R.R. HOFFMAN
, 1980
"... We describe a newly established research project called SoftLab in the area of computational science and computational engineering. The SoftLab project attempts to link physical laboratory experimentation with computer control and simulation to provide a virtual laboratory for computational science. ..."
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Cited by 2 (0 self)
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We describe a newly established research project called SoftLab in the area of computational science and computational engineering. The SoftLab project attempts to link physical laboratory experimentation with computer control and simulation to provide a virtual laboratory for computational science. We describe the overall project objectives and then introduce the three focus projects of SoftLab: Two Chemical Engineering SoftLabs (bioseparation and computational electronics) and a Mechanical Engineering SoftLab (computational mechanics). Preliminary results of our efforts are also described.
Towards Automatic Grid Generation using Binary Space Partition Trees
, 1994
"... The problem of discretizing threedimensional solid objects is considered. The objects may be presented in standard boundary representation. We discuss constructing from this representation a binary space partition tree, a data structure especially wellsuited to the geometric processing needed for ..."
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Cited by 1 (1 self)
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The problem of discretizing threedimensional solid objects is considered. The objects may be presented in standard boundary representation. We discuss constructing from this representation a binary space partition tree, a data structure especially wellsuited to the geometric processing needed for grid generation. We also give algorithms for generating fixedmesh grids and variablemesh grids adaptively. The method has been implemented on top of a solid modeling system. Key Words: Algorithms, three dimensions, rectangular grid, solid modeling. AMS (MOS) subject classifications: 65M50, 65N50, 68P05, 68U05. 1 This work has been supported in part by NSF Grant CCR8619817. Towards Grid Generation with BSP Trees 1 1 Introduction Solid modeling techniques are applied in mechanical simulation system for representing objects and detecting collisions in dynamic simulation systems [2, 10, 11, 26], and they are also applied in systems for solving partial differential equations (PDE) to rep...