The new Batsuit features a complex exoskeleton of sliding armor that required a separate animation rig running on top of the character rig. The Batcape, however, didn't change from Batman Begins.

The concept for the release of the Batpod required very intricate mechanical articulation of the car's structure combined with wild over-revving and slewing wheel spin, which wasn't possible to set up as a practical effect under the restrictions of the shoot schedule. The Batpod is finally revealed as the Batmobile's exterior armored panels explode off in a shower of fragments. The slewing wheel spin was animated via keyframe, while the panel wobble was driven by Double Negative's in-house rigid body solver dnDynamite. The dynamics toolset was also used to blow the panels off the car and send them skittering around the underground freeway.

The Batpod's key feature is the pair of oversized tires that come from the front end of the Batmobile. "We developed a special animation rig that allowed us to slide the wheels out from the exploding wreck of the Batmobile whilst smoothly animating the Batpod on its crazy ride down the street," Franklin adds. "The digital Batpod was built from a detailed Lidar scan of the actual practical stunt bike, and textured to play full screen at full IMAX resolution. We also built a special Batman stunt double for the sequence in order to match the look of the stuntman who was riding the bike during the chase shots."

Creating BatdoublesM
Cyberscans of both Christian Bale and stunt driver Jean-Pierre Goy -- both in the Batsuit -- formed the basis of the digital double models. Unlike in Batman Begins, the new Batsuit features a complex exoskeleton of sliding armor that required a separate animation rig running on top of the character rig. No motion capture was used -- the animation was completely keyframed.

The Batcape was the one part of the costume that didn't change between the films, which allowed the team to reuse some of the geometry from Batman Begins. "However, the demands of IMAX meant our cloth simulation needed to be much more detailed," Franklin observes. "The final cloth animation is a combination of the Syflex cloth simulation plug-in for Maya, Maya's own N-Cloth simulator, soft body animation and had keyframed shape animation. For the Batpod chase sequence, we had to heavily modify our cloth simulation techniques in order to match the vigorous flapping and whipping of the real thing. The Batsuit's unique texture was created via a custom set of shaders that generated a lot of the surface detail procedurally, with additional hand-painted maps controlling specularity."

Double Negative met another match-the-real-thing challenge with a helicopter crash sequence. The digital crash had to bridge the gap between shots of the live action chopper flying down LaSalle Street and a practical in-camera special effects burning helicopter wreck tumbling along the road deck. "Working from Lidar scans and photo reference, we modeled a high detail IMAX-ready Jet Ranger chopper which was animated via key frame to catch the cables laid in its path by the Joker's henchmen," Franklin notes. "The high angle shots of the chopper also featured completely digital street environments, as it was impossible to get plates of the real street from these positions. For the shot of the chopper crashing into the building, we used a new in-house tool to create the clouds of shattering glass and debris. The final impact on the road featured extensive use of Maya's fluid dynamics and dnDynamite. The explosion is completely digital with no live-action elements used -- the fireball was rendered with DNB, our proprietary volumetric renderer."

Take It to the Next Level
For the team at Double Negative, The Dark Knight presented a welcome opportunity to revisit the world of Gotham City that it had helped to bring to the screen for Batman Begins -- and even top it, as the 2005 movie was already considered to be a high point in the company's history. Then, it had to take it to the next level with the IMAX sequences. "The 64-bit compositing pipeline and the revamped 3D tool set performed way beyond expectation with the result that the terrors once held by 4K and up are no longer of any real concern," Franklin concludes. "The critical response to the movie in early previews has been stunning, and the fact that the vast majority of the critics are seemingly unaware of the substantial contribution that the visual effects made to the finished film only goes to vindicate the monumental effort that everyone on the team put into the show. We hope that The Dark Knight represents a major new stage in the development of digital visual effects as part of the cinematic story telling process. If the audiences believe our artifice to be the real thing, then that's OK by us!"

Alain Bielik is the founder and editor of renowned effects magazine S.F.X, published in France since 1991. He also contributes to various French publications, both print and online, and occasionally to Cinefex. In 2004, he organized a major special effects exhibition at the Musée International de la Miniature in Lyon, France.