Digital Characters in the Motion Picture Industry:
Gollum in Peter Jackson's The Lord of the Rings

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The two main techniques used in animating Gollum were motion capture and the "older, traditional style of animation which is called 'key-frame animation.'" (Producer Barrie Osborne; "Taming of Smeagol," 2002). Key-frame animation is when animators create several frames of major movements, then a sophisticated computer program automatically fills in smaller movements, creating a steady motion from one frame to the next. Many Gollum scenes were filmed using motion capture, but some could only be done using key-frame animation. For instance, one scene in The Two Towers shows Gollum crawling vertically down a rock face. Because it would be very dangerous and time-consuming for Andy Serkis to actually do this, the scene was done entirely in key-frame animation. Another drawback to motion capture is that it can’t do very intricate things like finger movements, which can only be key-frame animated. Many scenes used a combination of motion capture and key-frame, getting the major movements animated first and then going back and adding details like finger movement.

For sequences where Gollum was very physically interacting with other actors, Weta used a technique they called “roto-animation.” For instance, at the beginning of The Two Towers, there is a scene where Gollum is fighting with Frodo and Sam. Since it would be practically impossible to do a convincing “mime pass” for this scene, “what we could do is sort of superimpose our Gollum character onto Andy and literally mimic Andy’s motion,” says Jim Rygiel, “So we’re basically rotoscoping, which is tracking his motion frame by frame.” (“Taming of Smeagol,” 2002). Since Gollum is thinner and smaller than Andy, the animators would place the digital image of Gollum into the frame and then digitally erase Andy from it. Peter Jackson goes further into detail on the technique of rotoscoping, explaining, “This is not a new technique. I mean, this has been around since Snow White and the Seven Dwarfs. Disney often shot live-action performers, and then had his animators basically use them as reference… That simple live-action reference that Disney found so helpful 50, 60 years ago, was also a really great way to go for us.” To the right is a sample picture of Andy Serkis on set fighting with Sean Astin (Sam) and Elijah Wood (Frodo), followed by the finished footage with Gollum digitally “roto-animated” into the scene.

After Andy shot the scenes on set, he would later do motion capture work for the same scene. Because of the special cameras and computer equipment need for motion capture, it was not possible for it to be done on set during the initial filming. Instead, it was done in an empty studio, with a few set pieces or blue screen representations of set pieces as needed. Peter Jackson describes the motion system as using, “not cameras that shoot film, but simply cameras that gather the electronic data that’s reflecting off of these little points… And the motion capture system allows you to look at that in real time. A very crude model of Gollum was actually on our screens as we were doing the motion capture, so over here would be Andy moving around and you’d just flick your eyes from Andy down to the screen and you were seeing a rough version of the Gollum character doing the same thing.” Remington Scott, Motion Capture Supervisor at Weta, adds, “What [motion capture] does is it gives us a 3D representation of Andy in the digital world. Basically what we’re getting is his body movement and his skeleton movement.”

Through these two processes, motion capture and key-frame animation, the digital effects team at Weta were able to create one of the most convincing digital characters in film history. The three Lord of the Rings films, The Fellowship of the Ring, The Two Towers, and The Return of the King went on to win many nominations and awards from film academies worldwide, including a total of 17 Oscars from the Academy Awards in the United States. The character of Gollum and the achievements of Weta Digital and the entire Lord of the Rings crew have set another milestone in the continuing development of visual effects in film.