Better with Bubbles: Enhancing the Visual Realism of Simulated Fluid

Abstract

We present a method for including the visual effect of bubbles in a computer graphics fluid simulation, thus enhancing the illusion of realism for a splashing fluid. Previous fluid simulation methods have not included bubbles. Bubble creation is integrated into the particle level-set fluid simulation algorithm. Individual bubbles are approximated by spheres, which form more complex shapes where they intersect. The rendering of bubbles and fluid are integrated to create the appearance of one continuous surface. At the fluid-air boundary, we integrate bubbles whenever level-set marker particles pass from from the outside to the inside of the fluid. Thus, these particles represent air that has become trapped within the fluid surface. In addition, we detect empty pockets within the fluid, that are often formed due to turbulence, and create bubbles within this space. This is an inexpensive way of giving the impression that the air trapped in air pockets has become bubbles. Photo-realistic images of simulation results are rendered with a raytracer that has been enhanced to include caustics, and to handle bubble-bubble interfaces. Comparison of these images with images rendered without bubbles supports our position that the simple addition of bubbles to a fluid simulation greatly enhances visual realism.