Water Caustics

While preparing to make Moana, we envisioned the appeal of dancing patterns of light on the sand under clear, tropical seawater and we knew that capturing the beauty of water would be paramount. To reproduce this phenomenon in a realistic way, we implemented a technique called photon mapping which works by simulating the way light particles emitted from the sun scatter from the water surface and accumulate on nearby objects.

We also extended this to scale efficiently for vast oceans, emitting additional photons into the parts of the world that were seen more clearly by the camera. These techniques empowered artists with an automated way to generate caustics for the movie while still retaining artistic control over how they affected the final image.