It turns out that director Jon Chu was perfect for G.I. Joe: Retaliation. His previous experience with the last two movies in the Step Up dance franchise was the perfect training for the balletic action in the G.I. Joe sequel, in which the Joes are decimated and disgraced by a sneak Cobra attack.
And Retaliation required its own VFX Joes for support from Digital Domain, Industrial Light & Magic and Method Studios (under the overall supervision of James Madigan). But other than the obvious CG explosions and a brief bit of creepy morphing, the result is invisible VFX at its most proficient.
DD (supervised by Thad Beier) handled several key sequences, including an exploding motorcycle by baddie Firefly (Ray Stevenson), the Zeus space-based satellite, a tank battle, the reveal of the President as an imposter, and a massive ICBM explosion (the biggest simulation in DD history).
DD was challenged to create vehicles and aircraft that look fantastic but which are also plausible. That work included a fully-CG version of the Cobras' complex, high-tech HISS Tank, a counterpart to a practical tank model that had to appear photo-real and indistinguishable from the physical model, along with the Zeus satellite and the Cobra commander's dual jet engine-powered helicopter.
DD artists built two identical CG models of the HISS tanks, using a practical one as reference. Beier and the DD on-set team conducted a set survey, taking thousands of photos and HDR images of the tank and environment. Under Beier's supervision, artists from DD's partner team at Reliance in London then built the CG tank counterparts, with thousands of parts all shaded and textured, and integrated them into the plate footage of the practical HISS tank and mini-tank to create a massive battle. As the tanks roll, the treads pick up mud and dirt and kick up dust, all of which had to be created in CG to match the practical tank in every way, down to lighting, color and texture.
At the end, there is a spectacular explosion of a Zeus satellite, which is created and destroyed totally in CG. This sequence was actually a plot twist added just six weeks before delivery. Digital Domain was challenged to conduct the development work to determine how to explode the satellite in space and how best to break apart the model, as well as complete all shot work, in this extremely short period of time.
The art department created concept drawings of the satellite, and artists in London created a 3D model that was highly detailed, logically laid out and easily shared with other facilities. But because the detailed model looked so good, the filmmakers rewrote part of the movie's ending to add close-ups, and have it explode in space. This posed a challenge, so Beier envisioned an explosion in which flames would continue to expand and before eventually fading out. Digital artist Jeremy Hampton and the team created the effect in Houdini using a simulation that ripped the satellite apart in procedural way, based on DD's proprietary Drop system developed for 2012. The RBD simulation triggered and drove a pyroclastic blue fire explosion to finish off the effect.
Hampton and the team created the massive ICBM explosion, which, at 1 billion voxels, is the biggest simulation by far that the studio has ever created. The explosion was created based on reference footage of real MX Peacekeeper Missiles blowing up, where thousands of pieces of burning solid fuel leave distinctive smoke trails.
However, DD's most challenging shot lasts less than 10 seconds: the impersonation of the President by the Cobra henchman Zartan with the help of nanomites, the microscopic robots that form a living mask on his face, and reveal it in an unnerving scene where he appears to cut through his own skin to expose them.
Original plans for this shot were to achieve the transition between the President (Jonathan Pryce) and Zartan (Arnold Vosloo) photographically, by shooting both actors performing the same motion then blending them and adding the CG nanomites. When director Chu selected his desired performances, however, the two shots did not match, and the physical differences between the actors proved too disparate to bridge with a photographic approach.
Beier and the DD team then took the approach of creating CG models of each actor's head and using blend shapes, hand animation and the plate photography of the President to create the seamless transition from one to the other. The CG head models were created using the same geometry, point count and point order to enable the use of blend shapes to morph between the two models, using a 3D transition based on the topology of the face to control the movement of nanomites from one side to the other, which helped to even out the differences between the two head shapes. Because the shot is a full-face close-up, it was critical that the models maintained the features and characteristics of each actor, so in addition to using standard blend shapes, artists modeled and hand-animated facial expressions. Production VFX supervisor Madigan worked directly with DD's animators to art-direct specific facial movements. In the final shot, essentially the left side of the character's face (Zartan's likeness) is CG and the right side of his face (the President's likeness) is the plate photography, with the CG models of both faces blended between.
"In the end it looks mysterious and leaves you wanting more," remarks Beier.
Meanwhile, ILM (supervised by Bill George) got to tackle a stunning Himalayan fight sequence involving a group of ninjas hanging from ropes on the side of a sheer rock face. Interestingly, the sequence is based on the '84 G.I. Joe comic, Silent Interlude.
"We shot in an old warehouse where they constructed NASA rockets outside of New Orleans," George explains. "They created a green screen wall at a very steep angle with a lot of rigging above to swing the stunt people through for the fighting. But they couldn't move as fast as they wanted, so that's where we came in.
"We tried to capture the action with the stunt people going at it on ropes. So we'd take a performance that was 90% there and augmented it by, for instance, replacing an arm and having it swing in more aggressively. Getting onto the zip line was done CG. For us, it was the perfect scenario for doing digital doubles because they were completely covered up and the only face you saw was through their eye holes. It was a fairly easy match without cloth sim or hair sim to take it up to another level of difficulty."
Finally, Method in Vancouver and New York (supervised by Ollie Rankin) handled, among other things, an all-out assault on the G. I. Joe camp by a squadron of CG Apache attack helicopters, raining down machine gun tracer fire and missiles, blowing up every vehicle and killing almost everyone.
Later, a swarm of explosive CG robotic fireflies takes off and flies down the road toward a secret prison, activating their individual fluid-filled canister lights along the way and ultimately exploding once they are within range of the prison guards. Then, inside the prison, an escaped prisoner flees through a corridor as the malfunctioning cooling system explodes all around him, tearing up huge chunks of concrete and twisting metal. Software used included Maya, Mental Ray, Houdini, Mantra, Nuke, Photoshop and Avid.
"A lot of people get into VFX specifically for the opportunity to blow stuff up and G. I. Joe: Retaliation offered us at Method Studios many such opportunities, with Apache gunships on the attack, exploding robotic fireflies, Cobra ball grenades and a catastrophic cooling system meltdown," concludes Rankin.
Bill Desowitz is former senior editor of AWN and VFXWorld, the owner of Immersed in Movies (www.billdesowitz.com), a columnist for Thompson on Hollywood at Indiewire and author of James Bond Unmasked (www.jamesbondunmasked.com), which chronicles the 50-year evolution of 007 on screen, featuring interviews with all six actors.