Air Bubbles in Ice by Simulating Freezing Phenomenon

Ice is a material that is rich in visual details. To achieve a photorealistic image that represents ice in computer graphics (CG) is a challenging issue. Ice in nature is usually not transparent because it contains bubbles. Bubbles are one of the characteristics that define the appearance of ice since they scatter light. To manually incorporate many bubbles in a CG representation would be a daunting task. In this paper we propose a physically based method for creating a geometrical representation of ice with bubbles. The phase change from liquid to solid is considered because it is during the ice formation process that bubbles nucleate in the ice-water interface and accrete in ice. The ice-water interface position is determined by a particle level set method driven by the Stefan conditions. An implicit representation is used to calculate bubble formation in the interface, considering dissolved air in water. Simulation results are compared with actual photographs to evaluate the accuracy of our method.