Any modeling scheme for gaseous phenomena in graphics has to capture three aspects: the fuzzy geometry of the gas, the dynamics, characterized by the presence of vortices, and the interaction of light with the gaseous volume. We represent the gaseous volume as a particle system and apply Vortex Element Methods (VEM) to model the dynamics. A Lagrangian formulation that is gridless and hence ideal for unbounded flows is used. A gridless approach to ray tracing the particle systems is developed using particle maps. These maps are used to estimate densities within a gaseous volume analogous to the way volume photon maps are used to estimate radiance during Monte Carlo ray tracing. A technique is proposed to merge particle and volume photon maps to obtain an effective method for simulating multiple scattering in a dynamic inhomogeneous participating medium. Our method for modeling and rendering gaseous phenomena is conceptually simple and grid free. Particle maps play an effective role, as the nearest neighbor information obtained during the rendering phase is exploited during the dynamics computation. We preset results that demonstrate the effectiveness of our approach. Copyright © 2000 John Wiley & Sons, Ltd.