A Layered Wisp Model for Simulating Interactions inside Long Hair

This paper presents a method for animating long hair while modelling both interactions between the hair and the character’s body and between different hair wisps. Our method relies on a layered model paradigm. Hair is structured into a number of volumetric wisps whose motion and deformation are computed using a layered model: A first layer, the skeleton curve, computes the large scale motion of a wisp. This skeleton is coated by a second layer, the deformable wisp envelope, linked to the skeleton through highly viscous springs. A third layer is used for rendering the individual hair strands within each wisp. During motion, anisotropic interactions are computed between hair wisps, in addition to interactions with character body: two quasi-parallel wisps are allowed to interpenetrate while a viscous collision is computed between colliding wisps of different orientation. This results in a visually-realistic animation, that captures both continuities and discontinuities that can be observed in thick, long hair.