LOS ANGELES - It's not easy playing an ape, even a highly intelligent one, but if Andy Serkis succeeds in captivating moviegoers, he will be thanking the obscure world of "motion capture," a digital technology that accurately translates performance into animation.
For "Dawn of the Planet of the Apes," opening in US theatres this weekend, director Matt Reeves says he pushed the boundaries of motion capture to achieve "photo-reality" in rendering the apes, particularly in their facial expressions.
In doing so, "Dawn" could usher in a new age for actors, allowing them to dream of delivering award-worthy dramatic performances using a technology generally utilized in sci-fi blockbusters.
"One of the hardest things to do is to create characters which are emotionally engaging and truthful," said Serkis, a British actor who has become a seminal figure for motion capture by bringing to life creatures such as Gollum in "Lord of the Rings" and King Kong.
Serkis said advancements now mean that a character's facial expressions and emotions have a "one to one" relation to the actor's.
In the sequel to 2011's "Rise of the Planet of the Apes," Serkis plays Caesar, a brainy ape who leads his species and negotiates their interactions with humans.
In motion (or "performance") capture, multiple cameras record an actor playing scenes in a suit covered in hundreds of dot-like sensors, often against a green screen that visual effects artists then digitally transform into locations. The cameras capture the movements and feed them to computer software, where digital-effects artists animate characters accordingly.
For "Dawn," Reeves eschewed the green screen and instead had the actors playing apes don their motion-capture suits on location, interacting with the actors playing humans.
Once filmed, the scenes featuring the apes were sent off to Weta Digital, the New Zealand-based company that created the fantastical world of Middle Earth in "Lord of the Rings" and "The Hobbit" films.
The Weta artists digitally layered ape qualities, from their anatomy to fur to movements, onto the faces and bodies of the actors. Lighting was often key to the illusion: each individual strand of fur and the glint in the apes' eyes responded to the light of the forest.
Joe Letteri, the Oscar-winning visual-effects supervisor at Weta working on "Dawn," said making human movements mimic an ape's took enormous effort, but the emotion came from Serkis.
"If you look at (the film) side by side, there's no question that's Andy's performance," he said.