Stitching Together <em>Sucker Punch</em>

Yes, there is a method to the madness behind Zack Snyder's [1] Sucker Punch, the mind-bender about trying to escape from an insane asylum through the power of imagination. For her virtual rite of passage, Babydoll (Emily Browning) must defeat three massive samurai, a platoon of German zombies from World War I, a giant dragon and alien robots aboard a bullet train.

And when it came to dividing the four missions and 1,100 vfx shots, John DJ DesJardin [2], the overall visual effects supervisor, called on MPC Vancouver to tackle the Samurai sequence, Pixomondo to handle the World War I sequence, Animal Logic to create the Dragon sequence and Prime Focus to do the Bullet Train sequence.

"We extended what we learned from Watchmen as far as how we handled our digital characters and capturing shots on set and making the fights work right," confirms DesJardin. "It was a great chance for Zack, his long-time stunt coordinator Damon [Caro] and me to work closely.

"Damon and I came up with this idea called techvis with MPC. Zack could do action during rehearsal and we could quickly turn that into previs from what we captured with Damon and then we'd put that into our environment (a bullet train, a pagoda or a courtyard) and then Zack could set cameras in there. Then Zack would cut his scene before we even shot it in editorial, and Damon and I could take it apart and make these very complicated camera moves and fight moves that were pretty much maxed out in terms of what you could shoot for real and then identify with a lot of assurance what would be the CG stitching in between. We wanted to capitalize on what's been developed over the past several years to project actual footage onto geometry. We came to the conclusion early on that we could best help the girls in these fights if we took them to their limit and then use the CG to take them just a little further and then snap back into the range of what they could do so they're always grounded in something real."

Thus, it was in the creative stitching from digital double to live actor that really made the action smooth and seamless. This came out of two months of R&D that DesJardin initiated to deal with the Bullet Train sequence, which then became the axis for the whole movie.

The sequence required Prime Focus (supervised by Bryan Hirota) to develop a CG helicopter and helipad, alien-like terrains, interior and exterior shots of a magnetic levitation train that gets destroyed in a dramatic style, hoards of armed robots, CG doubles for the three actors and a futuristic metropolis called "Bunny City" inspired by Alien. One two-and-a-half minute shot, in particular, required the animation and render of nearly 20 minutes of material so Snyder could "time warp" everything down to the final length.

As for the robots, Snyder wanted a blank mirror face plate but with a little transparency so you could see underneath, where there's a camera system for an eye and other hardware.

Meanwhile, MPC (under the supervision of Guillaume Rocheron) brought the three samurais to life, combining real samurai armor pieces and detail onto the original, very stylized body proportions. Next, they accurately built the Japanese Pagoda and its surrounding environment, based on the original artwork and set plans by production designer Rick Carter [3] and his team so that each section and plank could be destroyed during the final fight against the machine gun samurai.

To handle the destruction work, MPC's software and vfx teams in Vancouver developed a new destruction system called "Kali" based on Pixelux's DMM, a finite elements solver usually used in the video game industry. This new approach allowed materials to flex and bend before breaking and the ability to define physical properties to realistically simulate wood, metal and stone breaking. It also gave the modelers the freedom to create assets without worrying about how they would break, eliminating the time consuming process of pre-cutting the geometry. MPC then implemented a full retiming solution into the pipeline, allowing artists to work on everything at 100fps and apply the final retime at render time to get accurate motion blur and animation interpolation. The compositing team then pieced together hundreds of CG layers for each shot.

Then, for the World War I sequence, in which Babydoll and her fellow inmates battle German storm troopers with steampowered mechanical faces on the battlefield and in the air, climaxing with the destruction of a giant Zeppelin, Pixomondo (under the supervision of Rainer Gombos) built and destroyed all aircraft, including a Meka, a futuristic armored endoskeleton. They used 3ds Max, Vray, Photoshop, Synthese, Nuke, FX Fume, Afterburner, Krakator, Thinking Particles and proprietary software.

"There were many meetings where Zack and Damon and I were talking Heavy Metal," DesJardin recalls, "and how that magazine, in particular, is responsible for a lot of us fanboys just thinking of these hybrid sci-fi/fantasy stories and environments: 'I want to have a WWI sequence where the girls go in and kick German ass. What if I have some zombies? Cool!'

"We knew Pixomondo's work from The Red Baron, so we figured they would be ideal at building the World War I environment and assets. The only thing we did was give them a face lift to give the scene a sci-fi, steampunk vibe. But Pixomondo made the giant Zeppelin. Rainer really tricked that thing out: there's detail that I never even dreamed of. He even pushed the steampunk guys that I asked for out on the strut near the engine to the nth degree."

For the Dragon sequence, Animal Logic (supervised by Andy Brown) designed and built the entire volcanic environment and a medieval castle. In order to establish the battle between knights and orcs, they used a combination of motion capture, Massive software and hero animation in Softimage. A proprietary tool was written for viewing and animating Massive crowds in Maya that added speed and efficiency. The dragon fire was created using the proprietary "Snap," developed on Snyder's Legend of the Guardians [4], but on a much larger scale for Sucker Punch. The R&D department also wrote a custom hair sim tool called "Alfro," for its first foray into digital doubles with long hair, when Babydoll hangs suspended from the dragon.

In fact, the dragon was inspired by Dragonslayer, per DesJardin's suggestion."Zack actually liked one of the Harry Potter dragons and we looked at that first," DesJardin explains. "We fine tuned it to make it more like Dragonslayer: immense wings for cool flight, the neck is shorter but the spikes come off the face the same way. We also studied the motion blur that Phil Tippett achieved with his Go-Motion technique. We took that and ran with it because we knew we had to do the flight attack with the airplane."

Bill Desowitz is senior editor of AWN & VFXWorld.