Surrounded by zombies

IT was the wee hours of a rainy morning in New York City’s Washington Square -- and “I Am Legend’s” monsters weren’t working. “Our original ‘design’ was stunt people in foam latex prosthetic makeup running naked through the park at night,” says overall visual effects supervisor, Janek Sirrs (“Batman Begins”). Near frozen, the actors voiced legitimate fears about falling or, worse, breaking their necks on the slippery terrain.

That’s when director Francis Lawrence and producer Akiva Goldsman (who shares a screenplay credit with Mark Protosevich) realized it might have been a bit hasty to begin production without a beefier concept for the flesh-eating night creatures. They had planned to follow the playbook of previous adaptations of Richard Matheson’s seminal science fiction novel, “I Am Legend,” and use stuntmen to portray the victims of a deadly infection that destroys the entire human race except one man, Neville (“Legend’s” Will Smith).

Now, as the crew and stunt people shivered in the freezing rain, the filmmakers asked the effects team, “Can we buy ourselves time in the design process by making all the creatures digital?” Sirrs and the others agreed. “It was a big, big decision, but it was the only choice,” Sirrs says.

Sirrs turned to Sony Pictures Imageworks (SPI) -- which was already removing all signs of life from “Legend’s” locale, New York City -- to supply the digital boogeymen. SPI’s artists first looked at gibbons, hyenas and other animals to inspire a different kind of feral ferocity. But imposing animal traits on humans “seemed hokey,” says SPI’s visual effects supervisor, Jim Berney (“The Lion, the Witch and the Wardrobe”). Instead, “They had to be humans, amped.”

SPI’s solution: transform human motion capture data into supercharged CG character animation. Instead of being naked, the stuntmen would wear neoprene suits covered in capture markers on set, which enabled Smith to interact directly with his antagonists, the so-called Infected. “Will was able to feed right off the characters in the scene, instead of acting opposite a tennis ball,” says SPI animation supervisor David Schaub.

SPI’s artists used the data as a foundation for some of the shots of the Infected but mostly relied on the talents of their animators, who hand-animated their inhuman aspects and complex emotions -- without turning these rage-filled creatures into cartoons. “The Infected don’t speak, so there’s a lot of emoting through their eyes and expressions,” Schaub says. “They’ve got this really high metabolism, so they’re always hyperventilating. That’s not in the performance capture, that’s a layer of animation we added -- little twitches and things to give them that Infected quality.”

‘Supercharged’ Infected

In the end, the Infected aren’t merely anthropomorphic characters -- they’re basically us. Naturally, we’re going to look at them critically. So when they had to run at incredible speed, chasing Will Smith in his SUV, SPI’s artists kept asking themselves: What would Olympic athlete Carl Lewis do? “Take longer strides,” Schaub concluded. “We altered the motion capture data to extend their legs, so the Infected cover more distance without changing the run dynamic. It still looks believable but subtly supercharged.”

Subtlety went out the window when the Infected were exposed to sunlight, which acts like acid on their mutated flesh. “They throw themselves against walls, down stairs and flop around on the ground like fish,” Schaub explains. “We’d really amp the motion capture performances and animate their heads repeatedly slamming into the pavement -- because that feels better than getting burned!”

Pushing human-like movement to its limit revealed the virulent hive mentality of the Infected -- particularly when they attack Neville. “They’ll go after their prey even if it kills them,” Schaub says.

Finally, SPI’s modelers also put an insane level of digital detail into each Infected, whose translucent skin reveals multiple layers of bones and muscles beneath. “Detail is our friend,” says Berney, whose crew also built and animated Infected rats and dogs as well for a total of nearly 800 visual effects shots.

The benefits were legion. “Making the Infected humans completely digital freed us up to do things we couldn’t do with prosthetics,” Sirrs says. “We didn’t want to go too far, as these were meant to be people with a ‘problem’ -- they had to be monsters but also get the sympathy vote.”