The London-based VFX house details its work on creating crowds of zombies for the Brad Pitt-starring blockbuster.
Summer blockbuster World War Z includes a lot of zombies – as thousands of the creatures rampage across the world killing (and turning) the people they encounter – and a large part of this was created by MPC, tapping their in-house crowd simulation software ALICE.
Led by MPC's VFX supervisor Jessica Norman, the house completed more than 450 shots for World War Z. The firm worked under both the film's original VFX supervisor John Nelson and his replacement, ILM's Scott Farrar. Key scenes that MPC worked on included creating hordes of zombies overwhelming Jerusalem, a plane-crash sequence, and the epilogue.
The largest portion of MPC’s work was for the sequence in Jerusalem, where live action plates gained a mix of CG environments, humans, zombies and helicopters – plus dust and other effects layered around these.
For the huge crowd scenes, MPC’s CG supervisor Max Wood captured mocap clips, adapted MPC’s proprietary crowd system ALICE, and tested the technology needed to render the scenes.
The crowd characters were built from reference photography and scans gathered on set. Modelling 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.
To attack the helicopters, the zombies climb on top of each other to form pyramids. For this the team began with geometry, which was then populated based on inclination using ALICE. The larger pyramids typically included around 5,000 agents.
In all of the complex crowd shots, MPC then added layers of hand animated figures. For falling and landing figures, they used PAPI, its in-house rigid body dynamic solver (based on the Havok physics engine).
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.