Computer Modelling Of Fallen Snow Paul Fearing

Figure 1: A sudden snowfall comes to the North Pole. In this paper, we present a new model of snow accumulation and stability for computer graphics. Our contribution is divided into two major components, each essential for modelling the appearance of a thick layer of snowfall on the ground. Our accumulation model determines how much snow a particular surface receives, allowing for such phenomena as flake flutter, flake dusting and wind-blown snow. We compute snow accumulation by shooting particles upwards towards the sky, giving each source sur-face independent control over its own sampling density, accuracy and computation time. Importance ordering minimises sampling ef-fort while maximising visual information, generating smoothly im-proving global results that can be interrupted at any point. Once snow lands on the ground, our stability model moves mate-rial away from physically unstable areas in a series of small, simul-taneous avalanches. We use a simple local stability test that handles very steep surfaces, obstacles, edges, and wind transit. Our stabil-ity algorithm also handles other materials, such as flour, sand, and flowing water