Animation Studios Fig. 1. Smoke trail that stretches from near the camera to the horizon, using a single simulation. The number of emi ed vorticles is specified in screen space. We present a multi-scale method for simulating incompressible gases in 3dimensions with resolution variation suitable for perspective cameras and regions of importance. The dynamics is derived from the vorticity equation. Lagrangian particles are created, modi ed and deleted in a manner that handles advection with buoyancy and viscosity. Boundaries and deformable object collisions are modeled with the source and doublet panel method. Our acceleration structure is based on the FMM (Fast Multipole Method), but with a varying size to account for non-uniform sampling. Because the dynamics of our method is voxel free, we can freely specify the voxel resolution of the output density and velocity while keeping the main shapes and timing.