Pahi: A Unified Water Pipeline and Toolset

We present Pahi, a unified water pipeline and toolset for visual effects production. It covers procedural blocking visualization for preproduction, simulation of various water phenomena from large-scale splashes with airborne spray and mist, underwater bubbles and foam to small-scale ripples, thin film and drips, and a compositing system to combine different elements together for rendering. Rather than prescribing a one-size-fits-all solution, Pahi encompasses a number of state-of-the-art techniques from reference engineering-grade solvers to highly art-directable tools. We do a deep dive into the technical aspects of Pahi components and their interaction, and discuss practical aspects of its use on Avatar: The Way of Water. We were honored to be awarded the Visual Effects Society (VES) 2023 Emerging Technology Award for this work.