Geometric pinching can result in cloth simulation output that is a tangle of cloth. We present a technique that eliminates pinching problems prior to simulation. The subsequently solved cloth simulations are cleaner, less tangled, and execute faster when compared to the no preprocessing case. The core algorithm is formulated as a general case mesh problem enforcing a minimal distance invariant, and thus it is applicable to a wide variety of geometric problems. We provide results from its use on feature film productions.

A new approach to surface modeling and reconstruction is developed which overcomes some important limitations of existing surface representations methods. The approach features two components. The first is a dynamic self-organizing oriented particle system which discovers topological and geometric surface structure implicit in visual data. The oriented particles evolve according to Newtonian mechanics and interact through long-range attraction forces, short-range repulsion forces, and coplanarity, conormality, and cocircularity forces. The second component is an efficient triangulation scheme that connects the particles into a continuous global surface model that is consistent with the inferred structure. A flexible surface reconstruction algorithm is developed that can compute complete, detailed, viewpoint-invariant geometric surface descriptions of objects with arbitrary topology. The algorithms are applied to 3-D medical image segmentation and to surface reconstruction from object silhouettes.>

Splines and deformable surface models are widely used in computer graphics to describe free-form surfaces. These methods require manual preprocessing to discretize the surface into patches and to specify their connectivity. We present a new model of elastic surfaces based on interacting particle systems, which, unlike previous techniques, can be used to sptiL join, or extend surfaces without the need for manual intervention. The particles we use have longrange attraction forces and short-range repulsion forces and follow Newtonian dynamics, much tiie recent computational models of fluids and solids. To enable our particles to model surface elements instead of point masses or volume elements, we add an orientation to each particle’s state. We devise new interaction potentials for our oriented particles which favor locally planar or spherical arrangements. We also develop techniques for adding new particles automatically, which enables our surfaces to stretch and grow. We demonstrate the application of our new particle system to modeling surfaces in 3-D and the interpolation of 3-D point sets.