The simulation of believable, photorealistic fire is difficult because fire is highly detailed, fast-moving, and turbulent. Traditional gridbased simulation models require large grids and long simulation times to capture even the coarsest levels of detail. In this paper, we propose a novel combination of coarse particle grid simulation with very fine, view-oriented refinement simulations performed on a GPU. We also propose a simple, GPU-based volume rendering scheme. The resulting images of fire produced by the proposed techniques are extremely detailed and can be integrated seamlessly into film-resolution images. Our refinement technique takes advantage of perceptive limitations and likely viewing behavior to split the refinement stage into separable, parallel tasks. Multiple independent GPUs are employed to rapidly refine final simulations for rendering, allowing for rapid artist turnaround time and very high resolutions. Directability is achieved by allowing virtually any user-defined particle behavior as an input to the initial coarse simulation. The physical criteria enforced by the coarse stage are minimal and could be easily implemented using any of the wide variety of commercially available fluid simulation tools. The GPU techniques utilized by our refinement stage are simple and widely available on even consumer-grade GPUs, lowering the overall implementation cost of the proposed system.

In this paper, we present an efficient method for simulating highly detailed large scale participating media such as the nuclear explosions shown in figure 1. We capture this phenomena by simulating the motion of particles in a fluid dynamics generated velocity field. A novel aspect of this paper is the creation of highly detailed three-dimensional turbulent velocity fields at interactive rates using a low to moderate amount of memory. The key idea is the combination of two-dimensional high resolution physically based flow fields with a moderate sized three-dimensional Kolmogorov velocity field tiled periodically in space.