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102
Meshless deformations based on shape matching
 ACM TRANS. GRAPH
, 2005
"... We present a new approach for simulating deformable objects. The underlying model is geometrically motivated. It handles pointbased objects and does not need connectivity information. The approach does not require any preprocessing, is simple to compute, and provides unconditionally stable dynamic ..."
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Cited by 129 (11 self)
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We present a new approach for simulating deformable objects. The underlying model is geometrically motivated. It handles pointbased objects and does not need connectivity information. The approach does not require any preprocessing, is simple to compute, and provides unconditionally stable dynamic simulations. The main idea of our deformable model is to replace energies by geometric constraints and forces by distances of current positions to goal positions. These goal positions are determined via a generalized shape matching of an undeformed rest state with the current deformed state of the point cloud. Since points are always drawn towards welldefined locations, the overshooting problem of explicit integration schemes is eliminated. The versatility of the approach in terms of object representations that can be handled, the efficiency in terms of memory and computational complexity, and the unconditional stability of the dynamic simulation make the approach particularly interesting for games.
RTDEFORM: Interactive Ray Tracing of Dynamic Scenes using BVHs
 In Proceedings of the 2006 IEEE Symposium on Interactive Ray Tracing
, 2006
"... Figure 1: Dress simulation: Four different images of a 210 step sequence taken from a dynamic cloth simulation and consisting of 40K triangles. By updating in realtime instead of rebuilding the BVH of the deforming model according to our heuristic, we are able to render the animation at 13 frames p ..."
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Cited by 60 (12 self)
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Figure 1: Dress simulation: Four different images of a 210 step sequence taken from a dynamic cloth simulation and consisting of 40K triangles. By updating in realtime instead of rebuilding the BVH of the deforming model according to our heuristic, we are able to render the animation at 13 frames per second with 512 2 screen resolution using a dualcore P4 processor at 2.8 GHz. We present an efficient approach for interactive ray tracing of deformable or animated models. Unlike many of the recent approaches for ray tracing static scenes, we use bounding volume hierarchies (BVHs) instead of kdtrees as the underlying acceleration structure. Our algorithm makes no assumptions about the simulation or the motion of objects in the scene and dynamically updates or recomputes the BVHs. We also describe a method to detect BVH quality degradation during the simulation in order to determine when the hierarchy needs to be rebuilt. Furthermore, we show that the ray coherence techniques introduced for kdtrees can be naturally extended to BVHs and yield similar improvements. Finally, we compare BVHs to spatial kdtrees, which have been used recently as a replacement for AABB hierarchies. Our algorithm has been applied to different scenarios arising in animation and simulation and consisting of tens of thousands to a million triangles. In practice, our system can ray trace these models at 313 frames a second on a desktop PC including secondary rays.
Fast proximity computation among deformable models using discrete Voronoi diagrams
 ACM Trans. Graph. (Proc ACM SIGGRAPH
, 2006
"... Figure 1: Multiple deformable models simulation: This sequence shows the positions of the objects at three time instances in a simulation. The environment initially consists of 10 deforming objects represented using 5.5K triangles. As the simulation proceeds, the objects break into 25 subobjects. O ..."
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Cited by 36 (6 self)
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Figure 1: Multiple deformable models simulation: This sequence shows the positions of the objects at three time instances in a simulation. The environment initially consists of 10 deforming objects represented using 5.5K triangles. As the simulation proceeds, the objects break into 25 subobjects. Our algorithm is able to perform collision and separation distance computations, including selfcollisions, among dynamically generated objects within 120 ms on a highend PC. We present novel algorithms to perform collision and distance queries among multiple deformable models in dynamic environments. These include interobject queries between different objects as well as intraobject queries. We describe a unified approach to compute these queries based on Nbody distance computation and use properties of the 2 nd order discrete Voronoi diagram to perform Nbody culling. Our algorithms involve no preprocessing and also work well on models with changing topologies. We can perform all proximity queries among complex deformable models consisting of thousands of triangles in a fraction of a second on a highend PC. Moreover, our Voronoibased culling algorithm can improve the performance of separation distance and penetration queries by an order of magnitude.
Consistent penetration depth estimation for deformable collision response
, 2004
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CoRdE: Cosserat rod elements for the dynamic simulation of onedimensional elastic objects
 IN PROC. ACM SIGGRAPH/EUROGRAPHICS SYMPOSIUM ON COMPUTER ANIMATION
, 2007
"... Simulating onedimensional elastic objects such as threads, ropes or hair strands is a difficult problem, especially if material torsion is considered. In this paper, we present CORDE(french ’rope’), a novel deformation model for the dynamic interactive simulation of elastic rods with torsion. We de ..."
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Cited by 29 (2 self)
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Simulating onedimensional elastic objects such as threads, ropes or hair strands is a difficult problem, especially if material torsion is considered. In this paper, we present CORDE(french ’rope’), a novel deformation model for the dynamic interactive simulation of elastic rods with torsion. We derive continuous energies for a dynamically deforming rod based on the Cosserat theory of elastic rods. We then discretize the rod and compute energies per element by employing finite element methods. Thus, the global dynamic behavior is independent of the discretization. The dynamic evolution of the rod is obtained by numerical integration of the resulting Lagrange equations of motion. We further show how this system of equations can be decoupled and efficiently solved. Since the centerline of the rod is explicitly represented, the deformation model allows for accurate contact and selfcontact handling. Thus, we can reproduce many important looping phenomena. Further, a broad variety of different materials can be simulated at interactive rates. Experiments underline the physical plausibility of our deformation model.
Realistic haptic rendering of interacting deformable objects in virtual environments
 Proc. of IEEE TVCG
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A Multigrid Framework for RealTime Simulation of Deformable Volumes
 WORKSHOP ON VIRTUAL REALITY INTERACTION AND PHYSICAL SIMULATION (2005) F. GANOVELLI AND C. MENDOZA (EDITORS)
, 2005
"... In this paper, we present a multigrid framework for constructing implicit, yet interactive solvers for the governing equations of motion of deformable volumetric bodies. We have integrated linearized, corotational linearized and nonlinear Green strain into this framework. Based on a 3D finite eleme ..."
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Cited by 26 (9 self)
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In this paper, we present a multigrid framework for constructing implicit, yet interactive solvers for the governing equations of motion of deformable volumetric bodies. We have integrated linearized, corotational linearized and nonlinear Green strain into this framework. Based on a 3D finite element hierarchy, this approach enables realistic simulation of objects exhibiting an elastic modulus with a dynamic range of several orders of magnitude. Using the linearized strain measure, we can simulate 50 thousand tetrahedral elements with 20 fps on a single processor CPU. By using corotational linearized and nonlinear Green strain, we can still simulate five thousand and two thousand elements, respectively, at the same rates.
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 20 (5 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
On fast construction of SAHbased bounding volume hierarchies
 In Proceedings of the 2007 IEEE/EG Symposium on Interactive Ray Tracing. IEEE
, 2007
"... Figure 1: We present a method that enables fast, perframe and fromscratch rebuilds of a bounding volume hierarchy, thus completely removing a BVHbased ray tracer’s reliance on updating or refitting. On a dual2.6GHz Clovertown system (8 cores total), our method renders the exploding dragon mode ..."
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Cited by 20 (3 self)
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Figure 1: We present a method that enables fast, perframe and fromscratch rebuilds of a bounding volume hierarchy, thus completely removing a BVHbased ray tracer’s reliance on updating or refitting. On a dual2.6GHz Clovertown system (8 cores total), our method renders the exploding dragon model (252K triangles) at around 13–21 frames per second (1024x1024 pixels) including animating the triangles, perframe rebuilds, shading, shadows, and display. The build itself takes less than 20ms, and is nearly agnostic to the distribution of the triangles; thus, the variation in frame rate (21 fps for the initial, smooth frame, and 13 fps for the timestep corresponding to the fourth image) is due only to varying traversal cost, without any deterioration in BVH quality at all (i.e., when starting with the last frame, the frame rate actually increases). With ray traversal performance reaching the point where realtime ray tracing becomes practical, ray tracing research is now shifting away from faster traversal, and towards the question what has to be done to use it in truly interactive applications such as games. Such applications are problematic because when geometry changes every frame, the ray tracer’s internal index data structures are no longer valid. Fully rebuilding all data structures every frame is the most general approach to handling changing geometry, but was long considered impractical except for gridbased grid based ray tracers, trivial scenes, or reduced quality of the index structure. In this paper, we investigate how some of the fast, approximate construction techniques that have recently been proposed for kdtrees can also be applied to bounding volume hierarchies (BVHs). We argue that these work even better for BVHs than they do for kdtrees, and demonstrate that when using those techniques, BVHs can be rebuilt up to 10 × faster than competing kdtree based techniques. 1
Planning motion in completely deformable environments
 In Proc. of the IEEE Int. Conf. on Robotics & Automation
, 2006
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