From Erwin Coumans:
Bullet 2.68 adds rope, cloth, deformable volumes interacting with rigid bodies, and officlal iPhone SDK support.
See http://bulletphysics.com for more info, download precompiled Windows and Mac OSX demos and iPhone video.
Category: Deformables
Fast Collision Detection for Deformable Models using Representative-Triangles
We present a new approach to accelerate collision detection for deformable models. Our formulation applies to all triangulated models and significantly reduces the number of elementary tests between features of the mesh, i.e., vertices, edges and faces. We introduce the notion of Representative-Triangles, standard geometric triangles augmented with mesh feature information and use this representation to achieve better collision query performance. The resulting approach can be combined with bounding volume hierarchies and works well for both inter-object and self-collision detection. We demonstrate the benefit of Representative-Triangles on continuous collision detection for cloth simulation and N-body collision scenarios. We observe up to a one-order of magnitude reduction in feature-pair tests and up to a 5X improvement in query time.
Fast Collision Detection for Deformable Models using Representative-Triangles
An Adaptive Contact Model for the Robust Simulation of Knots
In this paper, we present an adaptive model for dynamically deforming hyper-elastic rods. In contrast to existing approaches, adaptively introduced control points are not governed by geometric subdivision rules. Instead, their states are determined by employing a non-linear energy-minimization approach. Since valid control points are computed instantaneously, post-stabilization schemes are avoided and the stability of the dynamic simulation is improved. Due to inherently complex contact configurations, the simulation of knot tying using rods is a challenging task. In order to address this problem, we combine our adaptive model with a robust and accurate collision handling method for elastic rods. By employing our scheme, complex knot configurations can be simulated in a physically plausible way.
An Adaptive Contact Model for the Robust Simulation of Knots
Some Theses…
Frank Losasso’s PhD thesis on fluid simulation, which contains previously unpublished work on coupling together SPH and level set based fluid simulations:
Algorithms for Increasing the Efficiency and Fidelity of Fluid Simulation
Eftychios Sifakis’ PhD thesis on face, muscle, speech, and surgery simulation:
Algorithmic Aspects of the Simulation and Control of Computer Generated Human Anatomy Models
Geoffrey Irving’s PhD thesis on a variety of physics simulation topics:
Methods for the Physically-Based Simulation of Solids and Fluids
Update: While I’m doing the thesis thing, here’s a couple slightly older ones that are probably worth a look.
Adam Bargteil’s PhD thesis on liquid surface tracking.
Surface Tracking and Texturing
Bart Adams PhD thesis on point-based graphics:
Point-Based Modeling, Animation and Rendering of Dynamic Objects
Animating Corrosion and Erosion
In this paper, we present a simple method for animating natural phenomena such as erosion, sedimentation, and acidic corrosion. We discretize the appropriate physical or chemical equations using finite differences, and we use the results to modify the shape of a solid body. We remove mass from an object by treating its surface as a level set and advecting it inward, and we deposit the chemical and physical byproducts into simulated fluid. Similarly, our technique deposits sediment onto a surface by advecting the level set outward. Our idea can be used for off-line high quality animations as well as interactive applications such as games, and we demonstrate both in this paper.
Efficient Bounds for Point-Based Animations
We introduce a new and efficient approach for collision detection in point-based animations, based on the fast computation of tight surface bounds. Our approach is able to tightly bound a high-resolution surface with a cost linear in the number of simulation nodes, which is typically small. We extend concepts about bounds of convex sets to the point-based deformation setting, and we introduce an efficient algorithm for finding extrema of these convex sets. We can compute surface bounds orders of magnitude faster and/or tighter than with previous methods.
Cubic Shells
Hinge-based bending models are widely used in the physically-based animation of cloth, thin plates and shells. We propose a hinge-based model that is simpler to implement, more efficient to compute, and offers a greater number of effective material parameters than existing models. Our formulation builds on two mathematical observations: (a) the bending energy of curved flexible surfaces can be expressed as a cubic polynomial if the surface does not stretch; (b) a general class of anisotropic materials—those that are orthotropic—is captured by appropriate choice of a single stiffness per hinge. Our contribution impacts a general range of surface animation applications, from isotropic cloth and thin plates to orthotropic fracturing thin shells.
Time-critical distributed contact for 6-DoF haptic rendering of adaptively sampled reduced deformable models
Real-time evaluation of distributed contact forces for rigid or deformable 3D objects is important for providing multi-sensory feedback in emerging real-time applications, such as 6-DoF haptic force-feedback rendering. Unfortunately, at very high temporal rates (1 kHz for haptics), there is often insufficient time to resolve distributed contact between geometrically complex objects.
In this paper, we present a spatially and temporally adaptive sample-based approach to approximate contact forces under hard real-time constraints. The approach is CPU based, and supports contact between a rigid and a reduced deformable model with complex geometry. Penalty-based contact forces are efficiently resolved using a multi-resolution point-based representation for one object, and a signed-distance field for the other. Hard realtime approximation of distributed contact forces uses multi-level progressive point-contact sampling, and exploits temporal coherence, graceful degradation and other optimizations. We present several examples of 6-DoF haptic rendering of geometrically complex rigid and deformable objects in distributed contact at real-time kilohertz rates.
Adaptive Deformations with Fast Tight Bounds
Simulation of deformations and collision detection are two highly intertwined problems that are often treated separately. This is especially true in existing elegant adaptive simulation techniques, where standard collision detection algorithms cannot leverage the adaptively selected degrees of freedom.We propose a seamless integration of multi-grid algorithms and collision detection that identifies boundary conditions while inherently exploiting adaptivity. We realize this integration through multiscale bounding hierarchies, a novel unified hierarchical representation, together with an adaptive multigrid algorithm for irregular meshes and an adaptivity-aware hierarchical collision detection algorithm. Our solution produces detailed deformations with adapted computational cost, but it also enables robust interactive simulation of self-colliding deformable objects with high-resolution surfaces.
CORDE: Cosserat Rod Elements for the Dynamic Simulation of One-Dimensional Elastic Objects
Simulating one-dimensional 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 self-contact 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.
CORDE: Cosserat Rod Elements for the Dynamic Simulation of One-Dimensional Elastic Objects