Hi, I'm Mike Seymour of FXGUIDE.COM reporting for Wired

on the tech behind the visual effects of World War Z.

If I could get into Russia, where would I start?

Russia's a black hole. I need answers.

Some Amazing action sequences,

but to pull them off one of London's top visual effects

companies, the Moving Picture Company, or MPC,

had to effectively work out a formula for swarming zombies.

How did the filmmakers pull it off so well?

Well, the zombies are not animated by hand.

They're intelligent agents that are programmed

with a form of AI that allows them to interact.

MPC used their in-house program ALICE,

which normally allows these agents to avoid

bumping into each other, of course, here they needed

to climb all over each other as senior CG Supervisor

Max Wood from MPC explains.

MPC worked on many sequences in World War Z.

The largest of which was in Jerusalem, Israel.

The Israel sequence was shot in Malta.

The biggest challenge of this scene

was the large zombie crowd shots.

Our environment team built a large wall that surrounds

Jerusalem, and we see our zombies climb over it.

We also built a large CG environment outside the wall

with the wastelands in the backdrop showing Jerusalem,

all of this was built from photo reference.

Earlier on we received concept work showing

the different shapes the crowd could take.

Some were pyramid-like, and some were like

free-standing tentacles made of zombie crowd.

For the pyramid shots, we still have to find the shape

and the layout the crowd could take.

We then start populating the layer with motion-capture

clips including performers climbing up nets,

falling down ramps, and falling off objects.

The largest pyramid shots were made up

from around 5,000 zombies.

The digital zombies come from a database

built of motion-capture performances

which are then randomized with a core set of attributes

which have variance applied to bring out

what seems like thousands of different zombies.

Unlike, perhaps, the zombies in the film,

each of the intelligent agents in MPC's ALICE program

effectively have a mind of their own.

They act by being given an objective,

a set of rules to achieve it, and then a simulation is run.

Even the MPC artists have no idea exactly

whether or not they'll succeed when they started.

For the bus shot we used various different

motion-capture clips, including performers running up a ramp

jumping off from the height of the bus.

All the complex crowd shots have got layers

of hand-animated zombies, we start off setting the shots

of ALICE, our in-house crowd tool,

then we'd work out where we wanted to add

the additional animation detail.

One of the advantages of ALICE is it makes it really easy

to work between the different departments.

In the street scene we started off

working out the speed and the layout.

We got it to be very dense without having a flowing form.

In the front of the crowd we added fast-running zombies

that would sometimes fall over and end up

being eaten up by the zombies behind them.

As well as the end of the Israel sequence,

we see zombies attack a helicopter.

In some shots the helicopter was live action,

but in others, where they actually need to be more extreme

we added a CG helicopter that zombies could interact with.

What's amazing is not only did they simulate

all these agents, but they also simulated

their wave-like movement and then they added

cloth simulations, camera simulation,

and of course, photo-realistic lighting

on every single shot, that's a lot of simulations.

Well, if you want to learn more about the world

behind the visual effects of some of the

biggest blockbuster films, be sure to subscribe.

I'm Mike Seymour for Wired.