In Hahn's estimate, there are roughly 550 visual effects shots in "Hancock," and the majority of them are divided among the big set pieces in the movie, including a freeway chase, a train derailment, a bank robbery and a battle on Hollywood Boulevard. The latter involved closing down a block to traffic for multiple days and lots of CG augmentation.
One reason for that was the swarm of tornadoes they needed to add, which were revised numerous times. According to Hahn, it was difficult to devise a twister that looked real but still fit the stylized esthetic Berg was aiming for. "He wanted them to move in a very specific way," adds Villegas.
The 125-member Imageworks team was also responsible for effects you don't notice -- and aren't supposed to -- if they're done right. These include digitally erasing wires and palm trees, "putting walls where there weren't walls, and windows where there weren't windows. That's the most seamless work we've done in the movie," says Villegas proudly.
"Sometimes we'll add inn cityscapes," adds Hahn, offering the train derailment scene as an example. It was shot in Long Beach, California, but per Berg's instructions, "We added a vista of downtown Los Angeles in the background."
Imageworks also worked its digital eraser on some extra people in the Malibu beach scene involving Hancock and a beached whale, in addition to creating the CG leviathan. For reference on set, "A very small section of the whale, the front right quarter, was built as an animatronics with a moving eye," says Hahn, and a tossable prop was provided for Will Smith, but the effects team created a new cetacean from scratch in post-production.
Another tricky element for the VFX specialists involved close-up shots "that would transition from live actor to our CG version, or vice versa, within the context of one shot," says Hahn. The solution? Motion capture, a technique used in all-CG films like "Beowulf" and "The Polar Express" but also applicable to scenes in live action movies requiring digital doubles.
"After principal photography was done and there was a rough edit, we identified the transitions and we brought in Will and Charlize for a day each and had them act out very similar performances," outlines Hahn. To get as much detail as possible, they dotted the actors' faces with nearly 300 tiny markers, almost twice the amount used in "Beowulf." The result? A seamless, undetectable morph.
For Hahn and his team, previous experience on "Spider-Man" and other films was a distinct advantage. "I had some sense of what was achievable because of what we'd done previously. You're not constantly having to reinvent the wheel all the time," he says.
Nevertheless, the stakes are constantly rising. Filmmakers "want to improve upon things they've seen in the past, and do it faster and cheaper," notes Villegas. "And we never want to go in and recreate something we've seen before. We always try to bring something new to the table."
There were also some challenges to filming on location. Fly over to the next section to read about some of those.