Optimized Processing of Localized Collisions in Projective Dynamics

TL;DR

This paper introduces an efficient GPU-based method for simulating collisions in large volumetric elastic models by focusing on collision-prone regions and leveraging partial matrix factorizations for real-time performance.

Contribution

It presents a novel approach that enables interactive collision handling in large-scale models by exploiting model properties and partial factorizations, improving efficiency and robustness.

Findings

Supports models with over 500,000 elements in real-time.

Efficiently updates collision responses using partial Cholesky factorization.

Applicable to detailed models in animation and medical simulations.

Abstract

We present a method for the efficient processing of contact and collision in volumetric elastic models simulated using the Projective Dynamics paradigm. Our approach enables interactive simulation of tetrahedral meshes with more than half a million elements, provided that the model satisfies two fundamental properties: the region of the model's surface that is susceptible to collision events needs to be known in advance, and the simulation degrees of freedom associated with that surface region should be limited to a small fraction (e.g. 5\%) of the total simulation nodes. Despite this conscious delineation of scope, our hypotheses hold true for common animation subjects, such as simulated models of the human face and parts of the body. In such scenarios, a partial Cholesky factorization can abstract away the behavior of the collision-safe subset of the face into the Schur Complement matrix with respect to the collision-prone region. We demonstrate how fast and accurate updates of penalty-based collision terms can be incorporated into this representation, and solved with high efficiency on the GPU. We also demonstrate the opportunity to iterate a partial update of the element rotations, akin to a selective application of the local step, specifically on the smaller collision-prone region without explicitly paying the cost associated with the rest of the simulation mesh. We demonstrate efficient and robust interactive simulation in detailed models from animation and medical applications.