Physically-based Animation of Water Pollutant Diffusion

We present a physically-based animation method for simulating the diffusion of water pollutant in this paper. Our method allows animating the dynamic evolution of biological pollutants (e.g., water hyacinth, algae) on largescale water surface effectively. To enable the simulation of such a phenomenon in large scale virtual environment, we simplify the problem by considering the water pollutants as large patches or clusters of aquatic plants rather than each single aquatic plant. Since there exits obvious interface between the large patches of pollutants and the water surface, we model the evolution of the interface in our approach. We use 2D dynamic curves to represent the interface and the diffusion of the water pollutants can be regarded as the dynamic evolution and propagation of 2D curves. To alleviate the topological changes of 2D curves, we adopt a physically-based 2D level set model to animate the evolution and propagation of the interface. We build a level set equation to model the evolution of the interface. In addition, to handle the large scale virtual environment correctly in our physically-based level set model, an imagebased 2D voxelization method is proposed in the paper. In the voxelization method, the virtual environment will be converted to boundary conditions when solving the level set equation. Finally, the water pollutants diffusion phenomenon is simulated on large scale water surface by merging the interface animation results as well as the large scale virtual environment. Animation results about the algae propagation phenomenon in Taihu Lake show that our method is intuitively to be implemented and very convenient to produce visually interesting results.