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Feature Films VFX
Nyad
Wētā FX
Artists experimented with numerous techniques to realistically portray Diana Nyad battling the open water current and swells on her swim from Cuba to Florida. The main goal was to augment or replace the plate water to achieve a more dynamic, directional ocean, which was difficult to capture during filming which took place in a set tank.
To bring an authentic motion to the swells our FX team did over 300 realistic water simulations, including water geometry, geometric helpers and displacement ripples, foam, and bubbles. These were then all provided to the comp and lighting teams to ensure tight integration with the plate.
To create the dynamic motion of open water, we utilised a fast Fourier Transform based ocean spectra, using a real-time GPU-based system. This allowed us to quickly fine-tune the look, motion, and character of the water before we sim. Our custom toolkit, Pahi, was used to convert the initial ocean spectra into water deformations in Houdini to drive and integrate the simulations within our in-house simulation framework Loki.
Loki’s internal coupling framework allowed for state changing simulations within the same solve to properly transition bulk water to multiple different physical states. This gave flexibility to post-process the water geometry. Our Loki secondaries solver was used to create ripple displacements for capillary waves, bubbles, and foam to complete realistic water interactions.
We developed a new automation system that allowed us to tune different simulation settings in representative shots, and then propagate those settings across the sequence. The automation also enabled us to create geometric representations of water to help integrate the CG water and warp the plate, as well as generate speed diagnostics, whitecaps and water debris across multiple shots. Finally for the underwater shots, artists added turbidity, marine snow, and surface water to improve the underwater current and surface swell.