Check out the Knight and Day trailer and clips at AWNtv!

For Knight and Day, the lighthearted espionage thriller starring Tom Cruise and Cameron Diaz, director James Mangold naturally wanted real-looking bulls for the Spanish bull-run stampede. For Rhythm & Hues, it was a wonderful break from the usual talking animals.

"We had CG trains and cars and set extensions and greenscreen work and got to blow up a plane, but the biggest challenge were the CG bulls," suggests Greg Steele, the visual effects supervisor of Rhythm & Hues. "We went to Spain, blocked off a street and shot some footage with some running bulls in it and we had to augment that and increase the number of bulls. And actually some shots didn't have bulls, so we had to add them. There were usually nine to 15 bulls in each shot.

"It was actually nice not to do a talking animal for once. And that was Jim's really big thing: he wanted it to look realistic: the bio mechanics of how it moves and the weight of it."

The bulls were dangerous and uncontrollable to motion capture, but R&H shot as much reference footage as it needed to send back to the animators in LA. "We went out to the ranch where they were keeping all the bulls for this running stuff because we did have a couple of shots where we actually did put the bulls in there and Tom [Cruise] rode with them," Steele continues. "It was crazy and I can't believe that he did it.

"At the ranch, we set up a situation where we shot with three HD cameras and surveyed the place: a bull charging at someone, stopping and turning, the bulls skittering and bumping into each other. Then we also had an area where they ran along some fences to get some good biomechanical locomotion footage. We took some select pieces and tracked all of those and had some animators go in and rotomate to it. And that was important because it wasn't just a matter of replicating what the skin was doing; we had to also replicate what the bones were doing… and had to get to the core of what their motion was. So we had the animators go in and work the bone animation because we had simulations on top of all of this -- we built it from the inside out so the skin would simulate and would have all the right harmonics to the muscles as they moved through space and had the right gravity."

Steele says it was a fairly quick job: R&H had five months but didn't get most of the footage until mid-way through, which gave the studio about two months to build all of its assets.

"We started dropping these vignettes in and mixing things up," Steele adds. "Once the shot was locked in the way we wanted, we would go in and add nuance. For instance, two of the bulls are bumping into each other and we added some head rotations. We didn't want it to look too mechanical. The reference was great for all the texture detail and fur grooming that we needed to do."