A Rigging-Skinning Scheme to Control Fluid Simulation

Abstract

Inspired by skeletal animation, a novel rigging-skinning flow control scheme is proposed to animate fluids intuitively and efficiently. The new animation pipeline creates fluid animation via two steps: fluid rigging and fluid skinning. The fluid rig is defined by a point cloud with rigid-body movement and incompressible deformation, whose time series can be intuitively specified by a rigid body motion and a constrained free-form deformation, respectively. The fluid skin generates plausible fluid flows by virtually fluidizing the point-cloud fluid rig with adjustable zero- and first-order flow features and at fixed computational cost. Fluid rigging allows the animator to conveniently specify the desired low-frequency flow motion through intuitive manipulations of a point cloud, while fluid skinning truthfully and efficiently converts the motion specified on the fluid rig into plausible flows of the animation fluid, with adjustable fine-scale effects. Besides being intuitive, the rigging-skinning scheme for fluid animation is robust and highly efficient, avoiding completely iterative trials or time-consuming nonlinear optimization. It is also versatile, supporting both particle- and grid- based fluid solvers. A series of examples including liquid, gas and mixed scenes are presented to demonstrate the performance of the new animation pipeline.