Rendering the Sea: Exocortex Technology, Part 2

Quite often, simple things that occur in the real world can become incredible technical problems for visual effects artists attempting to digitally recreate or adapt those occurrences for film. One such gremlin is liquid simulation.

Previously, we looked at how Gradient Effects used the Exocortex Technologies Slipstream tool to create the memory pool in Harry Potter and the Deathly Hallows: Part 2, a sequence that required mimicking the effect of ink dispersing in water — in large volume and high detail. Slipstream allowed Gradient Effects to complete the sequence with far less processing power, with greater efficiency and in far less time than other solutions, thanks to real-time rendering and a specialized production pipeline.

But while rendering ink in water is impressive, the power and majesty of the deep blue sea is something else entirely.

Remaking a Classic: “Moby Dick”

In the summer of 2009, Canadian VFX supervisor Will Garrett was involved in preproduction on Germany’s Tele Muenchen Group TV remake of “Moby Dick.” Filming was scheduled to start in early fall on location in Canada and Malta with William Hurt, Gillian Anderson and Ethan Hawke in the lead roles.

The large production presented Garrett with a number of VFX challenges, including finding a cost-effective way to replace William Hurt’s left leg with a peg for specific shots (which was achieved, by the way, by using a color-neutral gray sock with reflective markers and a lot of skilled compositing). He also needed to incorporate both live-action footage and a computer-generated whale in many of the ocean sequences.

Because these sequences, particularly those featuring the whale, would be critical for maintaining the movie’s emotional hold on the audience, it was important to choose the right technology while staying within the made-for-TV budget. Garrett selected Exocortex for its innovative technology, experience with liquid simulation and ability to quickly adapt its software to the specific needs of the “Moby Dick” production.

Exocortex’s Maelstrom Technology

While Gradient Effects used Exocortex’s Slipstream technology for Harry Potter and the Deathly Hallows: Part 2, Garrett chose Exocortex’s Maelstrom technology for his project.

Exocortex’s Maelstrom is similar to Slipstream in that both were designed to overcome the speed and scalability limitations of existing simulation approaches. However, Maelstrom uses a multi-patent-pending adaptive tetrahedra simulator core, a first in the VFX industry. The development of this unique adaptive tetrahedra simulator is the result of a three-year collaboration between Exocortex and Christopher Batty, a renowned researcher at The University of British Columbia and Columbia University.

Moby Dick Productions was the first production company to experience the benefits of this new approach to liquid simulation. “Garrett was fun to work with,” says Ben Houston, the founder of Exocortex. “He has that rare and very effective combination of great interpersonal skills, an eye for detail and the ability to leverage new technology in demanding situations.”

Building a Custom Solution for “Moby Dick”

The first stage of the 10-month project involved integrating the core simulator technology into Autodesk Softimage to allow rapid iteration and the ability to rerun simulations to add further detail.

Next, the team applied Batty’s research innovations to achieve high-quality interaction between the liquid simulator and the intricate meshes that represented the whale and the boats. A spray, foam and bubble system was also created to handle breaking-water situations.

Finally, Exocortex pushed the scalability of the simulator by automating and optimizing its adaptive nature.

The project was a joint learning experience: Both Exocortex and the “Moby Dick” team learned how best to use the simulator and improve the software to meet the needs of the production. The end result was a uniquely scalable and adaptive tetrahedral-based liquid simulation system tightly integrated into an Autodesk Softimage workflow.

The extensive feature set of the simulator allowed its use on a wide variety of water shots, including whale chases and underwater sequences. In the end, over 150 shots used the Exocortex liquid simulator. “Exocortex’s custom software significantly enhanced what we were able to achieve on a made-for-TV production budget,” says Garrett.