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37
BDTree: OutputSensitive Collision Detection for Reduced Deformable Models
 ACM Transactions on Graphics (SIGGRAPH
, 2004
"... We introduce the Bounded Deformation Tree, or BDTree, which can perform collision detection with reduced deformable models at costs comparable to collision detection with rigid objects. Reduced deformable models represent complex deformations as linear superpositions of arbitrary displacement field ..."
Abstract

Cited by 98 (11 self)
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We introduce the Bounded Deformation Tree, or BDTree, which can perform collision detection with reduced deformable models at costs comparable to collision detection with rigid objects. Reduced deformable models represent complex deformations as linear superpositions of arbitrary displacement fields, and are used in a variety of applications of interactive computer graphics. The BDTree is a bounding sphere hierarchy for outputsensitive collision detection with such models. Its bounding spheres can be updated after deformation in any order, and at a cost independent of the geometric complexity of the model; in fact the cost can be as low as one multiplication and addition per tested sphere, and at most linear in the number of reduced deformation coordinates. We show that the BDTree is also extremely simple to implement, and performs well in practice for a variety of realtime and complex offline deformable simulation examples.
Collisions and Perception
 ACM Transactions on Graphics
, 2001
"... Level of Detail (LoD) techniques for realtime... In this paper, we are particularly interested in the problem of realistic collision simulation in scenes where large numbers of objects are colliding and processing must occur in realtime. An interruptible and therefore degradable collision handling ..."
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Cited by 64 (7 self)
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Level of Detail (LoD) techniques for realtime... In this paper, we are particularly interested in the problem of realistic collision simulation in scenes where large numbers of objects are colliding and processing must occur in realtime. An interruptible and therefore degradable collision handling mechanism is used and the perceptual impact of this degradation is explored. We look for ways in which we can optimise the realism of such simulations and describe a series of psychophysical experiments that investigated different factors affecting collision perception, including eccentricity, separation, distractors, causality and accuracy of physical response. Finally, strategies for incorporating these factors into a perceptually adaptive realtime simulation of large numbers of visually similar objects are presented.
Evaluating the Visual Fidelity of Physically Based Animations
, 2003
"... For many systems that produce physically based animations, plausibility rather than accuracy is acceptable. We consider the problem of evaluating the visual quality of animations in which physical parameters have been distorted or degraded, either unavoidably due to realtime framerate requirements ..."
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Cited by 47 (4 self)
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For many systems that produce physically based animations, plausibility rather than accuracy is acceptable. We consider the problem of evaluating the visual quality of animations in which physical parameters have been distorted or degraded, either unavoidably due to realtime framerate requirements, or intentionally for aesthetic reasons. To date, no generic means of evaluating or predicting the fidelity, either physical or visual, of the dynamic events occurring in an animation exists. As a first step towards providing such a metric, we present a set of psychophysical experiments that established some thresholds for human sensitivity to dynamic anomalies, including angular, momentum and spatiotemporal distortions applied to simple animations depicting the elastic collision of two rigid objects. In addition to finding significant acceptance thresholds for these distortions under varying conditions, we identified some interesting biases that indicate nonsymmetric responses to these distortions (e.g., expansion of the angle between postcollision trajectories was preferred to contraction and increases in velocity were preferred to decreases). Based on these results, we derived a set of probability functions that can be used to evaluate the visual fidelity of a physically based simulation. To illustrate how our results could be used, two simple case studies of simulation levels of detail and constrained dynamics are presented.
Adaptive MedialAxis Approximation for SphereTree Construction
 ACM Transactions on Graphics
, 2004
"... This paper presents a novel algorithm for the construction of spheretrees. The algorithm presented approximates ob jects,b oth convex and nonconvex, with a higher degree of fit than existing algorithms. In the lower levels of the representations, there is almost an order of magnitude decrease in t ..."
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Cited by 40 (0 self)
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This paper presents a novel algorithm for the construction of spheretrees. The algorithm presented approximates ob jects,b oth convex and nonconvex, with a higher degree of fit than existing algorithms. In the lower levels of the representations, there is almost an order of magnitude decrease in the numb er of spheres required to represent theob jects to a given accuracy. Categories andSub ject Descriptors: I.3.5 [Computer Graphics]: Computational Geometry and Ob ject Modeling  Object Hierarchies; I.3.7 [Computer Graphics]: ThreeDimensional Graphics and Realism  Animation General Terms: Algorithms Additional Key Words and Phrases: Animation, Collision Handling,Ob ject Approximation, Medial Axis Approximation, Simulation LevelofDetail 1.
Buckettree: Improving collision detection between deformable objects
 In Proceedings of SCCG2000: Spring Conference on Computer Graphics, Budmerice
"... In recent years, thanks to the increasing computational power available, real time computer animation has naturally evolved to model more complex and computationally expensive scenes. Consequently, all the problems concerning physical modelling need further research to tackle these new requirements, ..."
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Cited by 33 (3 self)
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In recent years, thanks to the increasing computational power available, real time computer animation has naturally evolved to model more complex and computationally expensive scenes. Consequently, all the problems concerning physical modelling need further research to tackle these new requirements, especially the problem of collision detection for deformable objects. Most existing solutions cannot not be trivially extended, because they are strongly based on the assumption that the shape of the object is fixed. In this paper we propose a general approach to reduce the cost of collision detection between deformable objects explicitly represented, regardless of the specific geometrical and physical manner in which they are modelled.
SphereTree Construction using Dynamic Medial Axis Approximation
, 2002
"... Collision handling is very computationally expensive, especially in large scale interactive animations. Hierarchical object representations play an important role in performing efficient collision handling. Many different geometric primitives have been used to construct these representations, which ..."
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Cited by 18 (0 self)
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Collision handling is very computationally expensive, especially in large scale interactive animations. Hierarchical object representations play an important role in performing efficient collision handling. Many different geometric primitives have been used to construct these representations, which allow areas of interaction to be localised quickly. For timecritical algorithms, such as interruptible collision detection, there are distinct advantages to using hierarchies of spheres, known as spheretrees. This paper presents a novel algorithm for the construction of spheretrees. The algorithm presented approximates objects, both convex and nonconvex, with a higher degree of fit than existing algorithms. In the lower levels of the representations, there is almost an order of magnitude decrease in the number of spheres required to represent the objects to a given accuracy.
Point Cloud Collision Detection
, 2004
"... In the past few years, many efficient rendering and surface reconstruction algorithms for point clouds have been developed. ..."
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Cited by 14 (1 self)
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In the past few years, many efficient rendering and surface reconstruction algorithms for point clouds have been developed.
Levels of Detail for Crowds and Groups
, 2002
"... Work on levels of detail for human simulation has occurred mainly on a geometrical level, either by reducing the numbers of polygons representing a virtual human, or replacing them with a twodimensional imposter. Approaches that reduce the complexity of motions generated have also been proposed. In ..."
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Cited by 13 (1 self)
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Work on levels of detail for human simulation has occurred mainly on a geometrical level, either by reducing the numbers of polygons representing a virtual human, or replacing them with a twodimensional imposter. Approaches that reduce the complexity of motions generated have also been proposed. In this paper, we describe ongoing development of a framework for Adaptive Level Of Detail for Human Animation (ALOHA), which incorporates levels of detail for not only geometry and motion, but also includes a complexity gradient for natural behaviour, both conversational and social.
TimeCritical Collision Detection Using an AverageCase Approach
 IN PROC. ACM SYMPOSIUM ON VIRTUAL REALITY SOFTWARE AND TECHNOLOGY (VRST 2003) (OSAKA
, 2003
"... We present a novel, generic framework and algorithm for hierarchical collision detection, which allows an application to balance speed and quality of the collision detection. We pursue ..."
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Cited by 8 (2 self)
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We present a novel, generic framework and algorithm for hierarchical collision detection, which allows an application to balance speed and quality of the collision detection. We pursue
Men Behaving Appropriately: Integrating the Role Passing Technique into the ALOHA System
 System”, Proceedings of the AISB’02
, 2002
"... The Adaptive Level of Detail for Human Animation (ALOHA) system is a platform for animating virtual humans within a virtual environment using levelsofdetail for geometry, motion and conversational behaviour. Until now the behaviour of these humans has been determined using predefined scripts. ..."
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Cited by 8 (2 self)
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The Adaptive Level of Detail for Human Animation (ALOHA) system is a platform for animating virtual humans within a virtual environment using levelsofdetail for geometry, motion and conversational behaviour. Until now the behaviour of these humans has been determined using predefined scripts. This paper describes the integration of the intelligent agent based rolepassing technique into the ALOHA system to allow for the creation of dynamic scenes.