“The challenge was in maintaining a level of visible detail on the characters while making them work together as a unit,” he explains.

One of Digital Domain’s more challenging visual-effects shots involved the awakening of the Foundation Army. In this sequence, thousands of dead labourers buried at the foot of the great wall of China, shake themselves free of the earth and rise from the ground.

“It was particularly tricky getting the scale correct for this effect,” says Andre. “We had to make it look as if it was a really big earth-shaking movement, as the supernatural army comes up out of the ground. It was something that we didn’t really have a lot of reference for in terms of a film that had done this before, but Rob had a pretty clear idea of what he wanted. While it was a challenging shot, it’s also one of the cooler shots in the film.”

“It was technically difficult because the sheer amount of volumetric data involved meant we had lots of layers to composite,” adds Larsson. “The layering was also constantly shifting depending on where the camera was, so combining the layers could be tricky because we had to make sure we couldn’t see through a layer to the one beneath.”

For the climactic battle between the rival armies, Digital Domain used Massive, the award-winning crowd-simulation software, combining Massive with motion-capture data.

“Massive was a natural choice for this, as the sheer number of soldiers demanded a procedural solution that would not only generate the number of characters but also give them the individuality the director desired,” say Larsson.

“It couldn’t be just a bunch of guys running around randomly; they needed to interact with each other and interact with the contents of the scene itself.”

The team used Massive for the background mass of characters, and the hero vignettes in the mid-ground and foreground. For characters seen in close-up, hand animation was added onto the mocap data. The team looked to Mel Gibson’s historical "The armies want to tear the hell out of each other. The final result is pretty gory – limbs get hacked off" epic Braveheart for inspiration when it came to the battle-scene.

“It’s one of the best battle films out there,” says Andre. “But what became apparent when looking at this film is that shots are set up where you see these two armies running at each other but you don’t actually see them hit.”

He goes on: “The shot goes from them running at each other to a little vignette of fighting, but in our shot we wanted to see the actual impact where these two armies that have thousands of years of hatred between them finally meet. They want to tear the hell out of each other and we wanted to show this. The final result is pretty gory, with characters getting stabbed and gouged and limbs being hacked off.”

Around 200 people worked for nine months at Digital Domain to create the visual effects shots. But, says Andre, working with Rob Cohen made those nine months fun.

“He is fantastic to work with – absolutely one of the best directors around,” says Andre. “He understand things from an artistic and story standpoint; and from a visual-effects standpoint. He even goes the extra mile to learn everyone’s name, which may sound minor but actually goes a long way to keeping morale up during the long weeks and months spent creating beautiful images for the film.”

Creating the Dragon Emperor mummy

Much like a Russian doll, the Emperor Qin mummy is formed of two hero characters – an ‘under-mummy’ that resemble a desiccated, burnt Jet Li, and the terracotta outer shell that resembles the actor in a more stylized way. The Mummy’s face was a mix of hand animation and meticulous procedural work, including stress maps that cracked the overlayed terracotta shell when it stretched beyond certain points.


The ZBrush model of the mummy


The basic animation model


A rough composite


The final composite




Massive was used extensively for the large scale battle at the end of the film. The software agents were built on the back of motion capture sequences and the shot was split into layers depending on the detail. Massive agents were used in all the background shots, with hand-animation added to mid-ground and close-to-camera characters. All the warriors were based on motion-capture data provided by four weeks of capture by Giant Studios.


Digital performer

Actor Jet Li is seen only briefly in human form at the start and end of the film, but key to the successful performance of the CG mummy was motion capture data and a photographic scan of the actor’s face. These, coupled with video references, of Li’s vocal performance helped bring the CG character to life.

CREDITS

Project: The Mummy: Tomb of the Dragon Emperor Client: Universal Studios
Studio: Digital Domain, digitaldomain.com
Software: Autodesk Maya, Pixar RenderMan, Pixologic ZBrush, Side Effects Houdini, The Foundry Nuke, Track, Storm (proprietary),Massive