Water, Water Everywhere

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Image Gallery from Sci-tech Winners

The Academy of Motion Picture Arts and Sciences'' Scientific and Technical Awards honored software innovation in fluid simulation such as the proprietary systems Industrial Light & Magic and Digital Domain used to create the ambitious sea battles in Pirates of the Caribbean: At World''s End. Photo: Industrial Light & Magic

If the Academy of Motion Picture Arts and Sciences' Scientific and Technical Awards had a mantra this year, it would be, “Water, water everywhere — and not a drop to drink.” With singular focus, the Academy turned its attention to the digital-fluid simulations that now swirl through movies, honoring six groups of software innovators at its annual February event in Los Angeles.

Fluid sims are proliferating in movies as directors envision ambitious sequences such as the sea battles in Pirates of the Caribbean: At World's End. Industrial Light & Magic (ILM) and Digital Domain contributed to that Oscar-nominated effects film, and teams from each studio received Scientific and Engineering Award plaques for their proprietary systems. The Academy's Technical Achievement certificates also recognized Rhythm & Hues' inhouse code, along with the developers of RealFlow, Autodesk Maya Fluid Effects, and Flowline software.

“One of the cool things this year is that the Academy is recognizing a lot of work done in the decade since Titanic [1997],” says Doug Roble, who shares the award for Digital Domain's Sim code with Nafees Bin Zafar and Ryo Sakaguchi. While Titanic famously employed a physical model, Roble says, “Tanks and models are very expensive when it comes to fluids. The basic rule of thumb is that fluids start to look stupid at about one-third scale. For Dante's Peak [also 1997], they flooded a valley with one-third-size cars, and it cost a bazillion dollars. That's when the bean counters said, ‘There's gotta be a better way.''”

For ILM, it found a better way in collaboration with Stanford University, whose PhysBAM (physically based modeling) engine helped the studio simulate monster waves for Poseidon (2006). That movie tanked, but the ILM-Stanford approach demonstrated that high-resolution simulation could be done on a production schedule. Previously, fluid simulation was so computer-intensive, it could take days to process a single sim. “We worked hard with Stanford to run our simulations across multiple machines,” says ILM's Nick Rasmussen, who shares the Academy prize with Frank Losasso Petterson and Stanford professor Ron Fedkiw. “By splitting sims into pieces and having our computers talking to each other, we were able to transcend what could fit on one machine.”

A ILM-Stanford solution to high-resolution fluid simulation on a production schedule garnered honors at the Sci-Tech Awards.

Poseidon also showcased simulations created with Flowline, the award-winning software developed at Munich-based Scanline Productions by Stephan Trojansky, Thomas Ganshorn, and Oliver Pilarski. That sim tool allowed the London-based shop Moving Picture Company (MPC) to convincingly flood the Poseidon's interior. Scanline then went on to sim the “liquid battlefield” in 300 (2007).

Fluid sims are becoming prevalent today, but moviegoers got early glimpses back in 1995's Waterworld, which reflected the research of Jerry Tessendorf, another of this year's Sci-Tech honorees. Tessendorf, who also contributed to the digital surface water in Titanic, was honored for the fluid dynamics software at Rhythm & Hues (R&H) — co-developed with Jonathan Cohen, Jeroen Molemaker, and Michael Kowalski. “One of the biggest challenges of simulating water is that we know a lot about what it looks like from everyday life,” Tessendorf says. “If you don't get it really close to right, it looks strange.”

Getting it “close to right” is a multipart problem — from the simulation of gross wave motion through secondary simulations of spray and mist. “One technical approach doesn't give you all the answers,” Tessendorf says. “When engineers research fluid dynamics to build bridges, they don't take one approach because it's an extremely complex problem. The Academy awards are very similar. … [They] cover a gamut of techniques.”

Jos Stam, an honoree for Autodesk Maya Fluid Effects, agrees. Stam has been researching simulation problems for a decade, and he has been recognized along with Duncan Brinsmead, Julia Pakalns, and Martin Werner. “Everyone has attacked the problem from different angles, although there are some things in common,” Stam says. Maya's approach defines a fluid as a grid comprised of interdependent cells that determine overall motion. But there's a computational limit to how fine you can make this grid. “That's where you add particles on top to ‘decorate'' the surface. The combination of grids and particles is the thing to do,” Stam says.

Accurately simulating the quick motions of water is difficult, covering a gamut of techniques—from the simulation of gross wave motion through secondary simulations of spray and mist.

While the science of fluid simulation may be clearer, the art of using it for movies is getting more complex. Director Gore Verbinski wanted the water in Pirates 3 to look realistic, but also do impossible things to serve the story.

“The term is ‘directability,''” says Ray Feeney, longtime member of the Academy's Sci-Tech committee. “You start with reality and then warp it to the director's vision.”

ILM's Rasmussen knows that challenge well. “You do water that's physically correct, but the director wants it deeper, or choppier. The challenge has been to do something plausible to the eye that obeys the laws of physics, but now we have to direct fluids to get the effect a director wants without overcontrolling it and making the physics go away.”

“You need a solid foundation of water that's physically correct, but that's just the starting point,” says Digital Domain (DD) honoree Ryo Sakaguchi, who worked on fluid sims in Pirates 3 and The Day After Tomorrow. “We then have to fight artistic controllability.”

Simulations that serve both the imagination of the audience and the vision of the director, were created by deserving recipients of technical honors at this year''s Sci-Tech Awards, such as Rhythm & Hues'' Michael Kowalski, Jeroen Molemaker, Jonathan Cohen, and Jerry Tessendorf (pictured, left to right).

“Everyone wants bigger, faster, and better simulations. But bigger sims get slower, and artistic control is all about doing more iterations,” Roble says. “Then there's that word ‘better.'' One of the big problems in fluid simulation is that it's easy to make a fluid simulator that simulates oil, but accurately simulating the quick motions of water is difficult. That's what we're all working on.”

“The trickiest part is the fine detail,” Tessendorf says. “It doesn't do any good to do a sim at low resolution and then try to build it up in stages. The whole process of adding details onto an existing simulation is an artistic demand that you can't meet by cranking up a number.” R&H uses a collection of software, including the AHAB sim tool and a scripting language for dealing with volumetric data called Fueled Expression Language Toolkit (FELT). “We can do brute-force simulations without a lot of detail, and we can then apply that in the scripting language to generate finer motion without much computational difficulty. You have to cheat the physics to make it work artistically,” Tessendorf says.

Animating believable fluids is one problem, and rendering it to look real is another. Today's sim systems feed directly into renderers. ILM's sim software operates within the studio's proprietary system Zeno, and current efforts are being directed at enabling artists to handle complex interactions between water and objects such as ships. “Everything we build is to achieve an effect — and then do lots of it,” Rasmussen says.

While proprietary sim systems provide the power and flexibility to achieve custom solutions, several studios that haven't built their own tools are still tackling fluid sims by purchasing Real Flow from Madrid-based Next Limit Technologies. Honored with a Technical Achievement Award, Real Flow has been used by Blue Sky Studios for Ice Age: The Meltdown, Asylum for National Treasure: Book of Secrets, and WETA Digital for The Lord of the Rings: The Return of the King. “Most of our customers come from the movie industry, so we've created a product for artistic use,” says Victor Gonzalez, who shares Next Limit's award with Ignacio Vargas and Angel Tena. “Artists don't want to deal with the math.”

Autodesk Maya Fluid Effects

Rhythm & Hues

Christien Tinsley won a Technical Achievement Award for the creation of the transfer techniques for creating and applying 2D and 3D makeup known as “Tinsley Transfers.”

Jörg Pöhler and Rüdiger Kleinke of OTTEC Technology GmbH won a Technical Achievement Award for the design and development of the battery-operated series of fog machines known as “Tiny Foggers.”

A Technical Achievement Award was presented to Sebastian Cramer for the invention and general design and Andreas Dasser (at podium), head of development at P&S Technik GmbH, for the mechanical design of the Skater Dolly and its family of products.

Left to right: Ignacio Vargas, Victor Gonzalez, and Angel Tena, who took home a Technical Achievement Award for the creation of the RealFlow software application.

Left to right: Jos Stam, Julia Pakalns, Duncan Brinsmead, and Martin Werner won a Technical Achievement Award for for the design and implementation of the Autodesk Maya Fluid Effects system.

Left to right: Thomas Ganshorn, Stephan Trojansky and Oliver Pilarski took home a Technical Achievement Award for the development of the Flowline fluid effects system.