King of the digital swingers: Can Peter Jackson's Weta studios allow anyone to play a gorilla?

David Phelan dons a motion-capture suit to try to ape CGI superstar Andy Serkis

In the breezy but temperate streets of Wellington, New Zealand, between one anonymous warehouse and another, sits a piece of Hollywood. Weta Digital, the special-effects house created by Sir Peter Jackson, has its headquarters in a sumptuous but understated mansion with spacious rooms and an elegant terrace. There's also a stunningly equipped screening room with flickering starlit sky above and super-comfy seats.

Weta was set up in 1993 and is responsible for the special effects on movies from Jackson's Lord of the Rings trilogy and King Kong as well as the recent Adventures of Tintin and Rise of the Planet of the Apes. It's earned them five Oscars, most recently for Best Visual Effects on James Cameron's Avatar.

In one of the rooms, I'm talking to Andy Serkis, supremely relaxed and affable, leaning comfortably into a voluminous leather sofa. Serkis rose to Hollywood prominence for his digitally enhanced performance as Gollum in The Lord of the Rings, a role he's reprising now in The Hobbit movies, filming now in New Zealand.

Right now, industry gossip is turning to next year's Oscar nominees and a campaign is under way on Twitter and elsewhere to get Andy Serkis nominated for his performance in Rise of the Planet of the Apes. He played Caesar, an ape with artificially enhanced intelligence, a central character in the movie. It's an arresting, detailed, utterly convincing performance. If the nomination happens, it will be a first for a motion-captured role.

Mocap, as it's abbreviated, is that process where an actor is poured into a form-fitting suit with tiny white balls attached and has his every movement digitally captured. Usually this is filmed separately to the main action, in a special studio called the Volume. However, Rise of the Planet of the Apes broke new ground by shooting mocap action outdoors, and with Serkis on location with the other actors, instead of being added in post-production.

Before speaking to Serkis, I tried on a mocap suit myself. My body was scanned as I performed basic movements and then my actions were recorded in the Weta Digital volume. It's a big, brightly-lit room with banks of desks creaking under the weight of computers, a carefully marked floor and scores of special cameras on the walls to register the mocap balls which were Velcroed to my every joint.

The new techniques used on Rise of the Planet of the Apes mean there's much more interaction between the actors than previously, as Serkis explains. He differentiates between motion capture and the latest techniques, called performance capture.

"At first with Gollum it wasn't even performance capture, it was motion capture and then the facial performance was shot on 35mm film. Then the animators rotoscoped – basically painted frame by frame over my expressions, matchframing every facial expression I made.

"The main difference now is this. I still filmed Gollum on location, I was in every single location and with the actors on real sets but the performance capture then had to be created months down the line in the Volume separately. So my performance was filmed on 35mm as Gollum. Then I repeated some of it for the motion capture. But with Rise of the Planet of the Apes, there's no disconnect. You're filming the live action actors and you're filming the performance captured performances in one hit. So it's all absolutely in the moment, everything happens on location, all in one beat and then we never have to go back and reshoot. And the same with Gollum this time."

The effects are so sophisticated and realistic now – there's not a real ape in the entire movie – does he think Hollywood will one day be able to manage without actors?

"That's entirely nonsense. Who is going to provide the emotional content to those scenes, who's going to drive that digital puppet if it's not an actor? Performance capture lends itself to live-action film-making.

"You can always tell the difference if you see a computer-generated character in a live action movie because it never has the right weight, it never feels its connected to the environment, there's never any messiness about it, it's too perfect."

So should a performance capture role be nominated for an Oscar? Serkis is too modest to suggest his own candidacy, but says: "For me as an actor there isn't any difference between playing a performance capture role or a live action role. I don't approach them any differently.

"For anyone who has been through the process of doing performance capture, it's just no more than acting. If I was wearing prosthetic make-up you wouldn't even be asking this. There are different ways of approaching performance capture but it's just digital make-up, basically."

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"I tried to convince myself and the actors that I was an ape. It's a complicated and intense process, involving a curious square-hipped walk, rolling shoulders and heavy leaning on crutch-like extensions to replicate ape dimensions. I did it for less than 15 minutes and was exhausted."

"When [director] Rupert Wyatt cuts the movie he's just editing for all the emotional content, for the pace of the scene, the drama. It doesn't really

matter what the make-up's like, is the emotional content there?"

Dressed in a grey tight-fitting suit, Serkis's face is covered with 51 dots for the mocap camera. "Head-mounted cameras are used to capture the face. So now you can go anywhere without worrying about occluding the cameras. You can get into all sorts of positions that the previous system didn't allow. So you have a lot more freedom to move."

"Caesar is based on a chimp called Oliver from the 1970s who walked upright. His expressions were almost human. And he'd sit down in a chair, pick up a glass and drink, have a cigar. He was believed to be progeny of man and ape, and when they discovered he wasn't, he was thrown into a sanctuary. They found him 30 years later, screwed up and broken."

"You don't actually get to see the visual effects until months down the line when they all start to come in and the visual effects shots begin to replace the actual thing, well after the final edit. And the animators can calibrate the character on the computer: you can dial the curvature of the spine, so you'll notice by the end of the movie Caesar's absolutely upright. He's more human in his movements."