Wired Science

How Physics and Computers bring an Ocean to Life for the Movies

Water seems like simple stuff, even when it's in motion. But try to fake it - like let’s say for a multimillion-dollar summer blockbuster movie - and you’ve got a problem. Until recently, computers couldn’t keep up with water's chaotic, differential equation - derived behavior. Then two movies came along, Poseidon, and the third Pirates of the Caribbean movie, that demanded serious computer-graphics derived water. So, the wizards at Industrial Light & Magic, along with some fluid dynamicists from Stanford, and a whole lot of computers, finally cracked perfect water.

Powerful forces like gravity, wind and motion make water difficult to simulate. In today's movies, effects makers use computers to create everything from a rat's fur to a starship. But water, with all its chaos, proved elusive.

For Pirates' climactic battle scene between two ships in a maelstrom, the effects team built two actual, 1-million-pound ships, mounted on gimbals to make them go up and down. That was the easy part. Then they had to figure out how to get computers to realistically generate the water, guided by the basic laws of physics.

In the end, it took a team-up of Industrial Light & Magic and a squad of computational physicists from Stanford University to teach computers to generate mathematically perfect water, based on a powerful set of rules known as the Navier-Stokes equations. Performing the simulation required thousands of computers running simultaneously - doing a job that would have taken a single computer about 1,000 years. The actual ships were then layered on top of those images. The result: a believable depiction of something that could never happen in the real world.

Take a closer look with Adam Rogers at how perfect water is created.