Making of Transformers 2

From Tech Radar, another article that gets into the technical challenges of creating the visual effects in Transformers: Revenge of the Fallen by Industrial Light & Magic and Digitial Domain. Few snippets below, the full article is here.

With animators often facing complicated 500-frame shots with three robots, Benza cast his staff according to their skill sets. "Some animators were interested in animating particular scenes, so I'd shift things around to give them a chance to do those shots," he says. "Specialists in animal behaviour would get the Ravage shots because he was a cat-based Decepticon. Others were specialists in dialogue and acting performances."

To create these performances, team members were aided by a rigging system developed by ILM for the previous movie, through which they could choose what parts of the model to connect. "An animator can animate any individual part or any groups of parts," Benza says. In addition, a new system provided the animators with a little procedural help on the more complex shots.

To make matters more complex, Devastator is so big and has so many parts that the animation crew couldn't treat him as a single asset. "When we tried to load the entire model in high res, it would grind the machines to a halt," Benza says. "We had two machines fail trying to work with him. One literally smoked. We don't know for sure if it was a direct result of working with this character, but it certainly did get overloaded – and fried."

"We designed the first version of the fight not knowing how it would be used in the movie, with Bumblebee and the cop car robot from the first movie, Barricade," says Benza. "Michael Bay liked how tight the edit was and the brutality when Bumblebee tears the limbs off, so he found a place for the fight in the movie and substituted a different robot [Rampage]."