Pascal Volino

Collision Detection for Deformable Objects

Interactive environments for dynamically deforming objects play an important role in surgery simulation and entertainment technology. These environments require fast deformable models and very efficient collision handling techniques. While collision detection for rigid bodies is well investigated, collision detection for deformable objects introduces additional challenging problems. This paper focuses on these aspects and summarizes recent research in the area of deformable collision detection. Various approaches based on bounding volume hierarchies, distance fields and spatial partitioning are discussed. In addition, image‐space techniques and stochastic methods are considered. Applications in cloth modeling and surgical simulation are presented.

Versatile and efficient techniques for simulating cloth and other deformable objects

We are presenting techniques for simulating the motion and the deformation of cloth, fabrics or, more generally, deformable surfaces. Our main goal is to be able to simulate any kind of surface without imposing restrictions on shape or geometrical environment. In particular, we are considering difficult situations with respect to deformations and collisions, like wrinkled fabric falling on the ground. Thus, we have enhanced existing algorithms in order to cope with any possible situation. A mechanical model has been implemented to deal with any irregular triangular meshes, handle high deformations despite rough discretisation, and cope with complex interacting collisions. Thus, it should deal efficiently with situations where nonlinearities and discontinuities are really non marginal. Collision detection has also been improved to efficiently detect self-collisions, and also to correctly consider collision orientations despite the lack of surface orientation information from preset geometrical contexts, using consistency checking and correction. We illustrate these features through simulation examples.

Efficient self‐collision detection on smoothly discretized surface animations using geometrical shape regularity

We present a new algorithm for detecting self‐collisionson highly discretized moving polygonal surfaces. If is based on geometrical shape regularity properties that permit avoiding many useless collision tests. We use an improved hierarchical representation of our surface that, besides the optimizations inherent to hierarchisation, allows us to fake adjacency information to our advantage for applying efficiently our geometrical optimizations. We reduce the computation time between each frame by building automatically the hierarchical structure once as a preprocessing task. We describe the main principles of our algorithm, followed by some performance tests.We present a new algorithm for detecting self-collisions on highly discretized moving polygonal surfaces. It is based on geometrical shape regularity properties that permit avoiding many useless collision tests. We use an improved hierarchical representation of our surface that, besides the optimizations inherent to hierarchisation, allows us to take adjacency information to our advantage for applying efficiently our geometrical optimizations. We reduce the computation time between each frame by building automatically the hierarchical structure once as a preprocessing task. We describe the main principles of our algorithm, followed by some performance tests.

From early virtual garment simulation to interactive fashion design

Virtual garment design and simulation involves a combination of a large range of techniques, involving mechanical simulation, collision detection, and user interface techniques for creating garments. Here, we perform an extensive review of the evolution of these techniques made in the last decade to bring virtual garments to the reach of computer applications not only aimed at graphics, but also at CAD techniques for the garment industry. As a result of the advances in the developments of virtual garment simulation technologies, we then detail a framework which fits the needs of the garment industry of virtual garment design and prototyping, concentrating on interactive design, simulation and visualization features. The framework integrates innovative tools aimed towards efficiency and quality in the process of garment design and prototyping, taking advantage of state-of-the-art algorithms from the field of mechanical simulation, animation and rendering.

Implementing fast cloth simulation with collision response

The article details and implements efficient techniques for cloth simulation, both in the area of numerical simulation and the area of collision detection and response. Emphasis is put on the efficient implementation of implicit numerical methods with many improvements toward better realism, as well as computation simplicity. A constraint based collision response scheme is adapted to this scheme in order to provide an accurate and stable collision response.

A simple approach to nonlinear tensile stiffness for accurate cloth simulation

Recent mechanical models for cloth simulation have evolved toward accurate representation of elastic stiffness based on continuum mechanics, converging to formulations that are largely analogous to fast finite element methods. In the context of tensile deformations, these formulations usually involve the linearization of tensors, so as to express linear elasticity in a simple way. However, this approach needs significant adaptations and approximations for dealing with the nonlinearities resulting from large cloth deformations. Toward our objective of accurately simulating the nonlinear properties of cloth, we show that this linearization can indeed be avoided and replaced by adapted strain-stress laws that precisely describe the nonlinear behavior of the material. This leads to highly streamlined computations that are particularly efficient for simulating the nonlinear anisotropic tensile elasticity of highly deformable surfaces. We demonstrate the efficiency of this method with examples related to accurate garment simulation from experimental tensile curves measured on actual materials.

Accurate Garment Prototyping and Simulation

AbstractDespite numerous methods available for cloth simulation, virtual garment prototyping has yet to find its way toward the garment industry, the main issues being simulation accuracy and the potentiality for reproducing the complex behavior of complex garment models. These goals can only be reached through an optimal combination of modeling techniques and numerical methods that combines high computation efficiency with the versatility required for simulating intricate garment designs. We here describe optimal choices illustrated by their integration in a design and simulation tool that allow interactive prototyping of garments along drape motion and comfortability tests on animated postures.

Animating wrinkles on clothes

This paper describes a method to simulate realistic wrinkles on clothes without fine mesh and large computational overheads. Cloth has very little in-plane deformations, as most of the deformations come from buckling. This can be looked at as area conservation property of cloth. The area conservation formulation of the method modulates the user defined wrinkle pattern, based on deformation of individual triangle. The methodology facilitates use of small in-plane deformation stiffnesses and a coarse mesh for the numerical simulation, this makes cloth simulation fast and robust. Moreover, the ability to design wrinkles (even on generalized deformable models) makes this method versatile for synthetic image generation. The method inspired from cloth wrinkling problem, being geometric in nature, can be extended to other wrinkling phenomena.

Collision and Self-Collision Detection: Efficient and Robust Solutions for Highly Deformable Surfaces

We present an efficient algorithm for detecting self collisions, as well as some techniques for evaluating collision inside-outside orientation in a robust way. As presented in [VOL 94], we detect collisions using a hierarchical algorithm that takes advantage of curvature properties giving us full power of hierarchical algorithms for self-collision situations. Determining the collision orientation may become a complex problem dealing with complex collisions reulting from highly deformable surfaces. We use collision remnance and consistency correction for computing collision orientation in a robust way, for accurate collision response in simulations involving highly deformed and wrinkled surfaces.

From early draping to haute couture models: 20 years of research

Simulating the complex fashion garments of haute couture can only be reached through an optimal combination of modeling techniques and numerical methods that combines high computation efficiency with the versatility required for simulating intricate garment designs. Here we describe optimal choices illustrated by their integration into a design and simulation tool that allow interactive prototyping of garments along drape motion and comfortability tests on animated postures. These techniques have been successfully used to bring haute couture garments from early draping of fashion designers, to be simulated and visualized in the virtual world.