Solid-state Culled Discrete Element Granular Systems

Abstract

Dry granular materials are common in computer animations, such as when a character drags a finger through sand or grabs a handful of wheat. However, simulating hundreds of thousands to millions of interacting particulates can take several minutes per frame or longer. More efficient granular material algorithms compromise visual accuracy due to granules complex behavior and detail. To shorten simulation times without sacrificing visual fidelity, we simulate individual granules close to the material s surface and use implicit surfaces and constructive solid geometry boolean functions to cull away solid-state granules beneath the surface and only replace them where the simulation requires. This surface dynamically updates in response to collisions or exposure from the surface granules. Our technique selectively removes the majority of granules for significant speedups, while staying flexible enough to cull out and repopulate granules to respond to multiple external forces.