Animation supervisor Andy Jones (left) and visual effects supervisor Erik Nash for Digital Domain were challenged by the sequence in which Smith walks into a hangar with 1,600 robots.

Once the MoCap data was converted into Maya files, Digital Domain wrote a program that allowed the animators to use both keyframing and motion capture within a single shot. First developed by Jones on Final Fantasy and The Animatrix, the tool mapped motion capture data onto keyframe controls. With this technique, a shot could start with 20 frames of MoCap of a running robot, then continue with 15 frames of a keyframed jump and resume with 20 frames of a motion captured walk cycle, all in one fluid continuous move.

Jones’ crew met a real challenge with a sequence in which Spooner walks among thousands of robots in a gigantic hangar. “We thought it’d be easy,” Jones recalls. “After all, the robots were standing still and we ‘only’ had to run some animation cycles… However, since the camera was moving, the shots featured a lot of parallax changes, which meant that we couldn’t simply project robot textures onto cardboard cutouts. In the tracking shots, they had to be three-dimensional models, a pretty amazing undertaking considering that there were 1,600 of them on screen. Interestingly enough, the script called for 1,000 robots but it just didn’t look enough once the scene was completed. So we kept adding robots until the shots finally looked right. The hangar itself was also completely digital, except for the portion around Will Smith. In the end, we had to pull every trick in the book to make this sequence work.”

Weta Digital was called in to create the car chase sequence in which Smith is attacked by robots. They completed the complex scenes in just 10 weeks. Photo credit: Weta Digital.

Attack of the Clones
Although Digital Domain remained the main provider of robot animation, Weta Digital was called in late in post-production to help complete the ambitious effort. “We started late in March 2004 and had only 10 weeks of full production time to deliver almost 300 shots,” observes in-house visual effects supervisor Joe Letteri. “It was a tremendous amount of work in a very short period of time. The main sequence that we worked on was the car chase. Spooner is attacked by two robot-driven trucks in a tunnel. When the robots fail to crush him with their vehicles, they call in for back-up and soon Spooner’s vehicle is swarming with dozens of machines, up to 160 units at the climax of the chase.”

Live-action plates were shot on a greenscreen stage with Smith performing the action in a car mock-up. The exterior of the vehicle was later completely replaced by a digital version and inserted into a CG tunnel. The timing of the animation was critical as the spacing of the light fixtures in the virtual environment had to be synchronized with the interactive light effects that had been used in the live-action photography. Working in Maya, animators created the complex choreography of the two trucks attempting to crush the car, and the movements of up to 50 robots at a time.