Building an Empire
Issue: Volume: 27 Issue: 4 (April 2004)

Building an Empire

Rome wasn't built in a day. It took approximately six months. At least, that's how long it took Stargate Digital to create a photorealistic 3D version of the ancient city used in a dramatic 35-second sweeping shot for the two-part miniseries Spartacus, airing mid-month on the USA Network.

The television production, like the 1960 motion picture starring Kirk Douglas, is based on Howard Fast's novel of the same name. And like the original movie, the miniseries follows Fast's story line about the real-life hero Spartacus, an imprisoned gladiator who led a slave revolt against the powerful army of the growing Roman Empire.

Filmed in Bulgaria and directed by Robert Dornhelm, the four-hour production contains more than 100 visual effects shots created by Stargate to achieve a period look. The artists formed armies of digital people, constructed numerous buildings, created a wide range of backgrounds and foregrounds, and crafted a plethora of props and weaponry, all of which were composited into live-action scenes. Some of these effects are 3D, others 2D. Some contain CGI, others composited filmed imagery. Some scenes are totally synthetic, while others contain only a few digital enhancements.

While the type and scope of the effects differ greatly from scene to scene, they have one commonality—they were intended to be invisible. "Spartacus was never conceived as an effects movie in terms of its visuals. Yet there was no way we could have done this project without them," says Eric Grenaudier, visual effects supervisor. "The effects move the story along and provided a discreet, cost-effective solution for depicting locations—and an entire era—that no longer exist."

As a matter of fact, many of the CG shots were not planned, but rather evolved out of necessity, from the digital reconstruction of Rome to the whip marks used for enhancing a scene in which Spartacus is flogged by guards.

In 73 BC, at the time of the revolt, the great Roman Republic was starting to evolve into what became the even more powerful Roman Empire. During the second and first centuries BC, Rome's military forces were acquiring lands to the east and west of the region. Although art, literature, philosophy, and other culture flourished, Roman imperialism also produced vast military plunder, particularly in the form of captured slaves.

While it appears that Spartacus was once a Roman soldier, his heritage had little bearing as authorities sold him into slavery. Sent to a training school for gladiators in Capua, he and approximately 80 others soon rioted, seized weapons, and escaped to Mount Vesuvius, where their ranks swelled to nearly 100,000 as word of the insurrection spread.

While some in the group wanted to escape by pushing north across the Alps and dispersing, others wanted to remain in Italy and pillage. But before their plans could be realized, they had to fend off legions of Roman soldiers, including those led by Marcus Crassus. The slave army eventually broke through Crassus's lines and pushed south, planning to sail to Sicily aboard pirate ships hired by the slaves. But the ships left without the rebels. Cornered, the men scattered, and many were eventually captured and crucified along the road between Capua and Rome, although the body of Spartacus was never found.
The majority of shots in Spartacus are live action with integrated digital elements ranging from CGI objects to 2D matte paintings, including the one incorporated into the background in this shot of Rome.

Telling this action-packed story required a number of sets, which were constructed as accurately as possible to retain a historical perspective. For the most part, the main locales, including the gladiator arena, were built practically in Sofia, Bulgaria, where principal filming occurred.

"You won't see the Colosseum because it wasn't built yet," notes Grenaudier. "We didn't add things that weren't there at the time just to establish that it's Rome." He does admit, though, that some liberties were taken with the city architecture to enable the director to describe many of the story points within the confines of the sets.

In addition to these physical locations, there are 2D matte paintings—including those used for the city of Capua—which were designed and constructed in Adobe's Photoshop. For added realism, many of the mattes contain embedded live-action elements composited with Adobe's After Effects. Still other sets were built in the computer, including Rome, which was a combination of CG and digital mattes with 3D camera moves applied to the 2D elements using Alias Systems' Maya Live and 2d3's boujou matchmoving software.

"In Rome, smoke is emerging from the marketplace and people and animals are roaming around in the street," describes Grenaudier. "Sometimes the people and animals are computer generated, while other times they are composited live action."
In this photorealistic shot of the ancient city of Rome, the team at Stargate Digital built 3D models in Alias's Maya, to which they applied photographic textures.

Conversely, the city of Rome that was featured in the shot at the beginning of the miniseries was entirely CG. For this scene, which sets the stage for the story, the virtual camera pans from a wide view of the city until it pulls into a close-up of Crassus on his balcony.

"Not only is this the most ambitious shot of the show, but it's also the most ambitious thing we've done at Stargate in terms of building a set," says visual effects producer Sam Nicholson, founder of Stargate, which creates a number of digital back-lot sets for prime-time television shows including ER, Las Vegas, and Crossing Jordan. "We wanted to make the scene big and dramatic, so we started with a bird's-eye view of Rome, and in the middle of it, we nested thousands of computer-generated people. Eventually, we transitioned to live action on a real set with a close-up of our leading characters—all without interrupting the shot."

The first 25 seconds of this 35-second shot is entirely synthetic—the carts, the road, the trees, the ground, the grass, the sun, the buildings, the people, the clothing, the props...everything. "Any-thing we needed to build Rome, we made," says Grenaudier. The deep backgrounds were created as matte paintings in Photoshop, while the foreground objects were modeled and animated with Alias's Maya and composited within After Effects. The textures, meanwhile, were photographic-based, acquired from hundreds of digital pictures taken on location by Grenaudier. The final scene was then rendered in Maya running on a renderfarm of Boxx Technologies workstations containing 3Dlabs' Wildcat4 7110 graphics accelerator cards.

According to Grenaudier, this segment was planned with a practical set that would be augmented with CGI. "We had a beautiful set built by an Italian designer, though it was limit-ed in scope, containing the senate, the slave market, and the houses of the main characters," he says. "However, out of necessity and de-sire, we changed direction and in-stead built everything in the computer." Prompting this decision was a malfunctioning camera cabling system that ran from a 150-foot-high crane to the edge of the balcony, as extreme winds on the day of the shoot shook the cable, causing the camera to become too unsteady.
Artists spent months building this all-CG set of Rome for a dramatic opening shot in the miniseries. In addition to the buildings and trees, the scene also contains a number of digital actors.

"That forced us to reconsider using live action," says Nicholson. "So while CG was a necessity at first, we soon realized the advantages this new ap-proach provided, allowing us to showcase the city and giving us the flexibility to change camera angles for optimal results, since the director was no longer limited to a downward-angle shot from the upper right side of the set."

One of the biggest challenges was to ensure that the virtual shot was perfectly synchronized with the live action. To accomplish this, the Stargate team projected the shot of Crassus onto the CG balcony of the virtual set, thereby providing the artists with a transition point. Prior to that particular slice in time, the digital artists could do practically anything, says Grenaudier, "as long as we found an elegant way to get back to that transition point when we were done." Notably, the artists didn't employ digital "cheats" to make the transition easier, such as using a large object, like a pillar, as an intermediate shot between the two environments. Rather, the transition to live action occurs as the camera is moving across the CG set. Moreover, the sequence occurs in broad daylight, which made it even more difficult to complete.

In all, a team of artists spent approximately six months re-creating this virtual Rome. But once they completed it, the group was able to reuse sections throughout the miniseries in a number of ways. "We can re-light it, take it apart, and build other sets from it," says Nicholson. "And it becomes a tremendous asset for us to use in the future as part of our growing virtual back lot."

Another complex sequence in the movie calls for thousands of slaves to descend from a cliff on Mount Vesuvius for a surprise attack on the Roman camp below. Shot against greenscreen on a small set, this live-action scene originally involved a few actors climbing down a rope. Stargate later expanded the shots in height, width, and depth, so in the end, the scene contained more than 200 slaves using multiple ropes to ease down a tree-lined, 200-foot-tall cliff during the middle of the night. "We shot the actors 20 feet off the ground so they could do their own descent without danger," Grenaudier says.

The team considered doing a large part of this sequence practically, according to Grenaudier, especially with all the cliffs in Bulgaria that could have served as a backdrop. "But we couldn't get around the safety issue associated with shooting that live," he says. Alternatively, the artists created the cliff, trees, and rope extensions in 3D, to increase the size of the set. Then, using as many actual terrain references as possible, they painted a digital matte for the environment below, to which they added 3D elements such as fire and smoke.
Artists expanded this greenscreen shot of actors climbing down ropes, turning it into a dramatic scene with 200 slaves descending a cliff before attacking surprised Roman soldiers camped below.

"We took still photos of some beautiful locations, and once we got approval from the director, we went back and took hundreds of close-ups of stones, tree bark, grasses, branches, and other objects, and used them as textures for our CGI. So, even though we built the final cliff in the computer, the essence of it is based on reality."

To enhance the scene, the artists also added crowds, as only a handful of the soldiers are real. This was done by digitally multiplying the men in postproduction using traditional rotoscoping techniques. For other scenes, though, larger crowds were needed. Within the CG city of Rome, for example, the artists created a number of virtual extras as well.

Some of the more inventive "unplanned" digital shots were created for a scene in which Spartacus and his men find themselves cornered by Roman troops on a peninsula. As a diversion, the slaves sent cattle and other livestock out of a thickly wooded forest and toward the Roman fortification with flaming bundles of sticks attached to their heads, allowing the rebels to escape under the cover of darkness.

"We tried to do this practically using live cows with Maglites attached to their heads so we could track the light in the computer and add CG fire," explains Nicholson. "But cows don't like to run, especially at night with 'fire' on their heads." In fact, they wouldn't even walk in the given direction toward the camera. They'd shake their heads and hit them against the trees to get the light off their horns, causing the flashlights to fall off and break.
For this live-action shot, digital artists filmed background plates at the Black Sea for the background, into which they composited a 3D pirate ship, built using historical data as a reference, on the horizon.

"It was the perfect example of old filmmaking meets new," Nicholson adds. "In pre-production, you have a bunch of producers trying to figure out how to get the cows to do this. With all their years of experience, everyone is an expert, but no one has ever done it, so you come up with some obtuse plan. Eventually, you get out there on location with a bunch of cows, like Eric did, and the animals don't react as you'd planned. So after all that planning, the scene winds up becoming completely CG."

In the completed version, this sequence begins as tiny points of light (a crowd duplication of black-clad extras holding torches) maneuvering through the woods toward the camera. Next, CG herds run across the open field and into the Roman camp. "And when they got so close to the camera that the CG cows didn't hold up, we added a few select inserts of the animals as they were prodded along from behind," describes Nicholson.

"We always try to use a combination of traditional set work and digital photography," continues Nicholson, "but at the end of the day, the digital often becomes a whole lot more predictable, especially in this instance."
The city of Rome was constructed in 3D, while Capua was created mainly with matte backgrounds. The image to the left shows the live-action set with actors as they were filmed against greenscreen. The image below shows the completed shot containing the dig

To animate the computer-gen-erated cows, the artists used BioGraphic Technologies' AI.implant. The crowd-duplication software pro- vided real-time interactive artificial intelligence for the rich character interactions, enabling the group to add realistic dynamics to the digital animals in the scene.

All told, Spartacus required 58 days of principal photography and another several months for creating the CGI and completing the postproduction work for the high-def miniseries. And despite all their efforts, Nicholson and Grenaudier hope that viewers will not notice their work.

"One of the biggest compliments we can get is if people watch this and ask what we did," adds Grenaudier.

Karen Moltenbrey is a senior technical editor atComputer Graphics World.

Alias Systems
BioGraphic Technologies
Boxx Technologies