Real-Time Rendering of Realistic Rain

In this report, we propose a new technique to render realistic rain in real-time using a commodity graphics accelerator. Our technique consists of two parts: off-line image analysis of rain videos, and real-time particle-based synthesis of rain. Videos of real rain are analyzed to extract the rain mattes; random samples of these rain stroke mattes are then used for online synthesis. We incorporate pre-computed radiance transfer (PRT) in our particle system to take into account the scene radiance. We show that there is a closed-form solution to the transfer function of a raindrop, making its evaluation highly efficient. Our approach achieves high realism with low computation cost and a small memory footprint, making it very practical. We demonstrate our technique on a variety of scenarios, from synthetic 3D scenes to real videos.