Real-time Volume Caustics Rendering in Single-Scattering Media

Volume caustics are beautiful patterns of light which are formed by light that first interacts with a specular surface and that is then scattered inside a participating medium. Although this phenomenon can be simulated, its generation process is usually non-trivial and time-consuming. Motivated by interactive applications, we propose a novel volume caustics rendering method for single-scattering participating media. Our method is based on the idea of volume photon mapping and simulates volume photons along reflected and refracted rays. Instead of storing photons inside the volume, we directly display their contribution to the final image using a GPU-friendly ray marching algorithm. The implementation of our method is straight forward and we show that it can be seamlessly integrated in existing methods for rendering participating media. We achieve high-quality results at real-time framerates even for large and dynamic scenes. Furthermore, we show that our method is a good approximation of a ground truth volume photon mapping simulation.