Abstract: Our goal is to simulate the full hair geometry, consisting of ap- proximately one hundred thousand hairs on a typical human head. This will require scalable methods that can simulate every hair as opposed to only a few guide hairs. Novel to this approach is that the individual hair/hair interactions can be modeled with physical parameters (friction, static attraction, etc.) at the scale of a single hair as opposed to clumped or continuum interactions. In this vein, we ﬁrst propose a new altitude spring model for preventing col- lapse in the simulation of volumetric tetrahedra, and we show that it is also applicable both to bending in cloth and torsion in hair. We demonstrate that this new torsion model for hair behaves in a fashion similar to more sophisticated models with signiﬁcantly reduced computational cost. For added efﬁciency, we introduce a semi-implicit discretization of standard springs that makes them truly linear in multiple spatial dimensions and thus unconditionally stable without requiring Newton-Raphson iteration. We also simu- late complex hair/hair interactions including sticking and clumping behavior, collisions with objects (e.g. head and shoulders) and self- collisions. Notably, in line with our goal to simulate the full head of hair, we do not generate any new hairs at render time.
(C) Andrew Selle, All Rights Reserved.