World War Z VFX Supervisor for MPC, Jessica Norman, reveals how to create virtual armies of zombies, plane crashes and transform one city into another.

Introduction

It's a busy Thursday morning at The Moving Picture Company where the company's London office has just turned in their final shots for World War Z, the post-apocalyptic epic starring Brad Pitt as a former UN investigator tracking down the source of a zombie pandemic.



With MPC's work on the film finally finished, visual effects supervisor Jessica Norman sat down to talk about the company's high-profile contribution, a large part of which involved extensive use of Alice, their in-house crowd system, to create entire armies of fast-moving zombies. "I've been on this show for two years," Norman relates, "so it's a bit sad after working with your little team for such a long time."

Building a Better Zombie

Much of the film's initial VFX shot list was initially divided between MPC and Cinesite, with two different tracks of design work done by Framestore and Legacy FX. As Norman recalls, "The split about which sequences went to which house was handled by the client, but one thing we did share was some of the zombie assets, with MPC doing the large build, for which we obviously built a lot of different characters.



"We had four different body types to deal with, and then we had to make a huge wardrobe of different clothing that could be mixed and matched. We would then send our human and zombie builds to Cinesite at various stages, and I believe we also built some of their costumes for the Philadelphia scenes. Apart from that, we really weren't working on the same sequences.

"Basically when people first turn into zombies, they are not as affected by disease, and I think the scenes that Cinesite were working on were just the first zombie stages, whereas we were working on stages one through three."



The bulk of MPC's early work took place for the Malta shoot, which doubled for Israel during scenes where armies of zombies form swarming human pyramids in order to scale the city walls and attack the panicked residents.



"We had to create a mix of stage one to three zombies all the way through the sequences," Norman explains, "so you might see different stages in the crowd, and depending on how close-up a shot would be, maybe the zombies would be stage three to get more readability on them, as well as to see the difference between zombies and humans. We also had to dirty down the zombie clothing, adding rips and holes to it, which worked better if they were all stage three."

"We had a photo booth set up in Malta, where we took scans of those characters, so we were able to build our characters based on what the makeups looked like"

A big challenge for the MPC team was the fact that their virtual zombies had to integrate seamlessly with the live-action zombie actors. "We had some excellent makeup and prosthetic work in Malta," recalls Norman, "as well as a number of performance artists who were trained in zombie 'body language,' and we used some of those characters as part of our motion-capture work in order to capture the essence of those performances in our CG characters. We had a photo booth set up in Malta, where we took scans of those characters, so we were able to build our characters based on what the makeups looked like.

"There were also shots where a digi-double takes over for an actor, when we had guys jumping over roofs and things like that, and there were a few cases where we did some CG enhancement on zombies, adjusting their heads or contorting their arms or legs. In the story, they come over the wall and land, so we did some augmentation to make it a little more brutal without being too in-your-face."



One of the biggest innovations in terms of zombie movement was the idea that the infected creatures would cluster together in fast-moving groups, even climbing over each other, ant-like, to reach their quarry.

"Some of those pyramids had 5,000 zombies in them"

"During pre-production," Norman remembers, "there was a lot of discussion about how they moved, how they ran, and how they would do anything - even climbing on top of each other - to get to their target. And then we talked about how that would look on a bigger scale. We started looking at patterns in things like schools of fish, or how these dense crowds would run down narrow alleyways and how the zombies with more energy would reach the front only to be taken down by the guys behind them.

"For the human 'pyramids,' we used a combination of different techniques. There was one scene where a bus is turned over by a massive army of zombies, so we used things like ramps with stunt performers coming over them. For the pyramids, we would start off by defining the general shape of it and then add different clips to it based on the inclination of the pyramid."

"We were constantly talking about things like our zombies being really fast, but you don't want to push it"

Despite the often frenzied movement of their digital zombies, Norman insists they still had to obey the basic laws of physics. "We were constantly talking about things like our zombies being really fast, but you don't want to push it. If we had some super-fast performances you just wouldn't believe it; the same with some of our large-scale crowd shots. Some of those pyramids had 5,000 zombies in them, so we had to rely on our crowd system - which worked really well - and pick our moments to make something you could believe.



"In order to make sure general physics applied, we had to make sure that the various characters were motion-captured at the angle the pyramid was at. And then we used things like Dynamic Solver, or as soon as somebody fell, you used Gravity or Rag Doll and all of that."

Re-drawing the Map

In addition to their work with digital zombies, the MPC team had a number of different responsibilities, from a sequence aboard a zombie-infested airplane in which the fuselage is blown open, disgorging most of its passengers, to several shots for the epilogue that take place from Egypt to India.

In other instances, existing locations had to be digitally transformed into other environments, such as turning Malta into Israel. "One of main scenes is set in the entrance where the buses come in, having travelled into the safe area of Jerusalem," Norman relates. "We had to replace the water in the real world outside with flat land, as well as buildings that were half-torn down and weathered, so we had to mix that in, adding more walls to a lot of shots.



"And at the end of the sequence where we look back and see Jerusalem, we used a combination of aerial plates we shot in Malta of smaller buildings and little villages. To sell the fact that it was really Jerusalem, we also used a lot of stills taken - rather handily - by one of our comp leads, a camera fanatic who was in Jerusalem on holiday. It was the perfect combination."

Looking Back on the Apocalypse

With the Moving Picture Company's work on World War Z finally completed, it seems a good time to ask Norman what lessons, if any, the shop will be able to take on to future projects.



"That's a difficult question to answer," she muses, "especially today where we've only just delivered, touch wood, our final shots. I think you sometimes need a bit of distance, especially when you've been working on something for such a long time. Because you've got so many 'babies', or zombies in this case, it's hard to decide what your favourites are.



"I think we learned a lot about the process of working between departments, using Alice our crowd tool as one of the things that brought everything together, and how well it worked. That was something I really enjoyed. I think some of those processes will be valuable, as we continue improving the tools we will be using in the future."

World War Z: Original Website

World War Z: Official Trailer

Jessica Norman: IMDB