Control of liquid simulations

Abstract

Over the last decade, advances in fluid simulation and rendering have helped animators synthesize photorealistic shots for movies that would have been virtually impossible to create by manually animating the liquid. Despite the advent of these computational methods, fluid simulation in movie production still involves a large degree of trial and error.

In this dissertation, we propose a set of techniques for creating animations of liquids that meet desired artistic criteria without the customary tuning of numerous physical parameters. The basis for our work is the mesh-based representation of the liquid surface which lends itself to efficient algorithms that can control the output of simulations.

First, we show how an animator can create animated characters and shapes that behave as if they were made of water using our mesh-based control method. Our approach allows for multiple levels of control over the simulation, ranging from the overall tracking of the desired shapes to highly detailed secondary effects. Next, we present a novel technique for interpolating between fluid simulations with free surfaces. We construct 4D spacetime meshes from animations and register them using a non-rigid ICP algorithm. By incorporating user input to align visually important regions, we can produce plausible animations that look like a blend of the two input sequences, all without re-simulating the fluid. We demonstrate how this could have applications in pre-visualization and video games.