Joe Letteri, visual effects supervisor for Weta, also created the digital Chicago skyline.

Creating the Future
Besides robot sequences, Letteri’s crew also tackled the creation of the futuristic Chicago skyline. Working from production paintings by Tatopoulos, Weta Digital used live-action plates of the Windy City to form the basis of the shots whenever possible. The first step was to map out a skyline in sketch form and submit it to Proyas. The concept was then blocked in digital form, once again submitted to Proyas, and finally redone in high resolution. “We built about 30 high resolution buildings for the foreground,” Letteri explains. “In the mid-ground, we had medium resolution buildings that were built from pieces of the main structures. By reorganizing the pieces and moving the buildings around, our cityscape would never look the same.”

The virtual Chicago was populated by extras that were either actors shot greenscreen for tight shots or CG models animated in Massive for long shots. “We also had six to eight different CG cars and about six truck models,” Letteri adds. “There again, by mixing pieces, we got enough vehicles to make a whole fleet.” Weta Digital also executed many digital set extensions, most notably on the glass-walled lobby of the US Robotics building, a responsibility shared with Digital Domain. “All the robot action was executed in keyframe animation,” Letteri notes. “The movements were too extreme to be motion captured. In several shots, Will Smith himself is a digital double. We used a CG model that was provided by Digital Domain — a very nice model, by the way. For the explosion that concludes the sequence, we had originally planned to use a miniature, but the action turned out to be too fast and too extreme for this approach. The explosion was eventually done in CG with particle systems and a series of tools that we had developed for the destruction of Mount Doom in Return of the King.”

Although it’s still hard to tell if Sonny will have the lasting impact of a C-3PO or a T-800, Proyas, Tatopoulos and the crews at Digital Domain and Weta Digital have definitely succeeded in creating a unique character. “What I’m the most proud of is that Sonny is the third biggest character in the movie and he’s completely digital all the time,” Jones concludes. “It was quite a challenge as I, Robot was Digital Domain’s first venture into large-scale character animation.”

Alain Bielik is the founder and special effects editor of renowned effects magazine S.F.X, published in France since 1991. He also contributes to various French publications and occasionally to Cinefex.