Retiming of fluid simulations for VFX
Ken Museth · 2019
We present a novel approach to retiming of fluid simulations, which is a common yet challenging practice in visual effects productions. Unlike traditional techniques that are limited to dense simulations and only account for bulk motion by the fluid velocities, our approach also works on sparse simulations and attempts to account for two (vs one) of the fundamental processes governing fluid dynamics, namely the effect of hyperbolic advection and parabolic diffusion, be it physical or numerical. This allows for smoother transitions between the existing and newly generated simulation volumes, thereby preserving the overall look of a retimed fluid animation, while significantly outperforming both forward simulations, which tend to change the look, and guided inverse simulations, which are known to be computationally expensive.