World War Z

CGSociety :: Production Focus

5 July 2013, by Paul Hellard





MPC, Cinesite and Framestore were among a clutch of VFX studios who collaborated closely to create the blockbuster of Max Brooks’ ‘World War Z’. CGSociety grabbed it and ran.



Starring Brad Pitt and directed by Marc Forster, World War Z revolves around an ex-United Nations investigator Gerry Lane (Pitt), who traverses the world in a race against time to stop a pandemic that is toppling armies and governments and threatening to decimate humanity itself. Under the guidance of Overall VFX Supervisor Scott Farrar, MPC VFX Supervisor Jessica Norman and the MPC the team completed more than 450 shots for World War Z. MPC’s main areas of work were creating the hordes in Jerusalem, the plane crash sequence, the Wales sequence and the epilogue.

“We did a sequence that is played in Israel, all actually shot in Malta,” explains Norman. “Some of the key shots would be what we call the Pyramid of Zombies. There are several shots with those kinds of pyramids. We built the big wall surrounding Jerusalem, protecting it from zombies. All the zombies tried coming in from outside trying their best to get there and therefore forming these pyramids.” Some of the zombies are climbing on the tower forming a little bit of a tentacle and grabbing the helicopter. “They do all the other crazy stuff like running down these little alleyways and they were almost like sloshing against the wall, they are behaving a little bit like water, just because of the sheer density of the crowd,” adds Norman.



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The largest portion of MPC’s work was for the Israel sequence, a combination of live action plates with added CG environments, CG humans, CG helicopters and FX passes for dust and helicopter wash. In creating all of the pyramids or towers of zombies, MPC started off doing a lot of motion capture. They started putting in layers since they are such a heavy crowd job. They didn’t want all the agents in there before knowing exactly what the shape needed to be. “So we would do rough blockings. We would put in geometry where the pyramids needed to be and try and define it first,” explains Norman. “Then we would populate the geometry or that area with our clips using our power crowd tool called ALICE, first used on 'Troy' for the battles on the beach, years ago. We showed a couple of guys like crawling on nets, crawling along and getting up, falling and all of that. So we would sort of populate the geometry and get all the zombies in the shape. There were specific little animated numbers to get like a little bit of interaction. There is one shot that begins really quite close up and the camera pulls back and reveals the whole pyramid. That falling was generated using our dynamic software, and sometimes there would be a crowd agent turning into a ragdoll falling, and then he would crash sometimes going into animation and sometimes back and up and running. So there is a lot of close work between our crowd and animation department.”

Fashion sense


The build was obviously quite massive. They needed to have so many zombies and then not have repeats, they created the build of 24 different body types, and then made a huge wardrobe of garments to throw on them, all in CG. The crowd characters were built from reference photography and scans gathered on set. Modeling Lead Ashley Tilley and Texture Lead Jung Yoon Choi oversaw the asset team, creating 24 different body types with different textures, which resulted in 3,000 crowd variations. Max Wood, MPC’s CG Supervisor, set up a little system so they could create many thousands of outfits. “I think we had 3,000 outfits that would be sort of ready-made to make sure that older women would not wear the flowery jeggings and all that,” explains Jessica Norman. “We could always go in and change it over if we liked. Using the ALICE crowd simulation software meant the MPC crew could call in those outfits as they saw fit. “We came up another little tool that was linked to ALICE again where we could make a QuickTime from a shot and it would tell you exactly who was in that shot by producing front and back views of those agents and also telling you exactly how many numbers,” she explained. “And then we wrote a little tool that would say these are all the guys that are wearing bright clothing, these are all the guys wearing blue and then we could reduce the numbers based on that. And that ended being really very useful, I don't think we thought about it before. So all the clothing items and the bodies were built based on the guys that were on site in Malta. So we had a photo booth set up, where we scanned and photographed the guys including clothing. So that is where the clothing idea comes from including their coloring. So then obviously on top of that we would do texture variations for each clothing item.” MPC’s Crowd team worked closely with the Animation department, lead by Animation Supervisor Gabrielle Zucchelli, to ensure that the figures moved realistically in a crowd and while interacting with the live action. For the larger crowds, they used MPC’s in-house cloth solver that is integrated with ALICE. One of the largest tasks for the lighting team, lead by Jonathan Attenborough and Wes Franklin, was to render crowds of up to 250,000 in a single shot.


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One of the greatest benefits in using the inhouse crowd sim for MPC is that it is so much part of their pipeline that they can very easily work closely in between departments. “We can create the crowd, go to animation and then take it back into the crowd sim. Adding in higher passes, and textures, clothes and such,” adds Norman. “It is just very useful in that way but it is sort of part of the whole MPC setup. Marco Carboni was our crowd lead and he did a fantastic job because there are always those improvements in all the areas that you need just to make the ALICE crowd software work just so.”

MPC did a lot of environment work. There were helicopters skimming over the towers and the helicopter crash. There were a bunch of plates set in this sequence where there was a crashing plane and then also a lot of work on the plane, you must have seen the trailer obviously, there is a whole blow and all that. There was some plastic prosthetic work but there is always need for some extra touch-up and extra crispiness. There were also a few shots towards the end of the movie where they get really close up to these characters so it just really calls for some very tight animation work. “Our animation team also did a fantastic job. It was just really good teamwork there,” adds Norman.



 

CINESITE

 



"Starting something new, you're taking a huge risk," adds director Marc Forster. "When you have a built-in audience, you can take bigger risks knowing it worked before. That's not a guarantee it's going to work again, but doing something more original I find more exciting and interesting."


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“Zombies are only part of the big effects in the ‘World War Z’ movie.” Matt Johnson - Cinesite



“The whole Zombie thing was thought about long and hard,” says Matt Johnson, VFX Supervisor at Cinesite. “ I know a lot of directors say this, but we did spend a lot of time in preproduction about the conventions and what form would our zombies take. In a film of this scale, we wanted to push the boundaries, to give it something different and distinct to some extent.”

The work involved extensive TD input and led to significant developments in Cinesite’s raytracing, lighting and shading pipelines. The way the zombies change and progress in the life-cycle can be seen in the behaviour of the creatures. As the movie progresses, the zombies can be seen to change and evolve and they become something different. There were four distinct zombie design stages which effect everything from their physicality of their appearance, through to their George Romaro movement, speed and behavior. Max Brooks the author of the graphic novel series, came along to the set and the VFX crew and modelers spoke with him at length about the story, the zombies as well as the part of the story which makes up the movie, because this is just one part of the complete World War Z story.

Pick apart Philadelphia


One large shot in the city reveal of Philadelphia had to be digitally evacuated of cars, pedestrians from the street, anything that would show a normal day. “Then in turn our crew populated the streets with waves of more desperate looking people walking on freeways, 100,000 people running.

The animation team tried to move away from the classic zombie movement and employed experimental dancers to study a new style. “The people we had in were in West End shows, in professional theatrical touring companies,” exclaimed Johnson. “We had the head of the troupe working on the stage play of ‘War Horse’ come in to help. The top experimental ballerinas in the world came in to experiment and improvise, and to work with the animation department to devise a new category of zombie movement in this new zombie movie.”

Even the best stunt man in the world, who Matt saw come on set at one stage, was helpful in devising the ravenous attack in the zombies. Rugby tackles were studied, where hands were leading to grab and pull the opponent down. Usually one’s hands are stretched out to lead, but also to protect one’s face. In these zombies, they were like humanoid attack dogs, leading with their jaws, to instantly bite and infect their target, before moving on. It’s a disturbing vision, but effective.”

Cinesite’s Matt Johnson supervised second unit for a lot of the work in Malta, even though it was finished by MPC. The collaboration was constant, open and deep. “We worked very closely with those guys I think we were all getting the movie looking as good as we can. I worked with Jessica Norman and we became good friends on set, coming up with a kind of cool look and obviously kind of sharing ideas to make the movie look as cohesive as possible,” says Johnson.


 

”It is just crazy seeing this kind of impossible tower of people so they are just kind of climbing on and standing on each other, all desperate to be the one that can get at the fresh meat to infect.



The close up crowd shots and the full frame digital doubles were definitely the most challenging shots. For the Philadelphia sequence there were several fully CG doubles. They had to create convincing, extreme close-ups of CG cloth and moving CG hair, especially for a zombie girl with a grey hoodie and long hair overhanging her face. There were close up crowd shots that were challenging because there were so many characters. It was too close to the camera to use a normal crowd approach, so we had to simulate everything as though they were going to be heroes.

The movie starts in the city of Philadelphia with stylistically a normal city life. They didn’t want it to look like a typical visual effects movie, but like ‘All The President’s Men’ film grading or that kind of visual style. There was lot of work done in the first part of the film but hopefully viewers won’t have any clue that there is VFX work done at all. “In fact,” says Johnson, “out of the entire production the only people who went to Philadelphia for shoot anything on the movie were myself and my visual effects still photographer Aviv Yaron. Everything else in Philadelphia is actually shot in Glasgow in Scotland.”

These guys had to take all the plate shots in Glasgow and create CG buildings, CG extensions, add elements of Philadelphia into the Glasgow location and impose a logic with some kind of weird kind of reality. “I worked out how you could take a layout in Glasgow and then the road layout in central Philadelphia and homogenise them to make them feel as though it was right,” says Johnson. “There are scenes featuring the Benjamin Franklin Bridge which is a kind of suspension bridge. We removed all the cars from that bridge and replaced the entire bridge with a gridlock which had police barricades, CG cop cars and CG traffic jams and then piled in hundreds of zombies and people swarming and fleeing.”

After the ambulance shunts past all the cars, including the one with our hero and his family, Brad exits his vehicle. He goes to pick up his smashed rear mirror of the road and you see Brad looking at the window reflection. He gets back in the car and a motorbike cop comes alongside. Suddenly a garbage truck smashes past the car and we work around to the inside of the car and you see the cop flying off into the air and the garbage truck just kind of driving down the street smashing cars out left right and centre, and then Brad and his family kind of drive in behind the garage truck trying to escape. While this was a VFX shot, Johnson and the Cinesite crew has four car interior mounted cameras capturing views of the exterior stunts as they were played out.

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“This allowed us to stitch those four plates together and then imposed camera moves, later on in post so for the motor bike cop, we were able to film the interaction a real actor and Brad in Glasgow and the vehicle. We shot plates with the cameras mounted in the Volvo where the garbage truck kind of came along and hit an articulated kind of dummy on the back of a very expensive Harley.”

This is a big budget movie so Matt tells me they just smashed that bike, an older vehicle tarted up for the shot. The garbage truck smashes through, so you have the impact of the garage truck and within a few frames, what is left is the real aftermath background sealed view from those four cameras, and a pan later into the reaction in the car, shot on the car interior in a green screen environment which was shot on stage at the studios in England. Looking through the windshield you have real Glasgow, real car and from that we have a full plate panorama of Glasgow with real stuntmen, real actions and assets. Shooting through the windshield of a car links the whole thing together. It takes place in under three seconds and no one will ever know. [Edt: until now.]


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On the roof


Johnson went to the top of the Town Hall in Philadelphia and shot huge high rise panoramic images so they could create exactly the kind of vista they wanted. There were views from the Harlem, mixed with buildings from the Lower East Side of New York. The elements were all brought back together using NUKE. There were some major developments to the render pipeline. This was the first movie where Cinesite adopted a physically plausible render pipeline, using RenderMan. This allowed the lighting crew to move away from using point-clouds to calculate indirect light to using ray-tracing instead. The lookdev became more important and we could set up shots much more quickly than before, with a consistent look across the show. “Using this hybrid approach of 3D projection, we were able to take the scene with the escaping family in the green screen. Projections consisted of traditional 2D, 3D and as they were rendered, we blurred the boundaries. The software is so integrated in terms of what you can do now, it is the lines between the traditional compositing package and the 3D package that are blurred so we thought we would take advantage of that as much as possible.”

Paramount Pictures and Skydance Productions present in association with Hemisphere Media Capital and GK Films a Plan B Entertainment / 2DUX² production.