When (not actually) in Rome

Shift a tiger, create thousands of Romans, bring a dead film star back to life... it's all in a day's work at Mill Films, the London post-production company that used state-of-the-art digital effects in Gladiator

An old Hollywood staple - the Roman epic - is revived in Gladiator, the first of this summer's blockbusters, courtesy of British director Ridley Scott and London-based post-production effects specialist Mill Film. The end result uses state of the art digital-effects technology to produce a heightened-reality vision of Roman life more than 2000 years ago... and to complete a number or scenes left unfinished after the death of one of the film's stars, Oliver Reed.

All in all, some 100 shots in the film were computer generated by Mill Film, which won the project against stiff competition from Hollywood effects specialists including Digital Domain and Industrial Light & Magic. This equates to about 12 minutes of footage that took more than four months of work to produce.

The end result illustrates the way forward for film effects, which, increasingly, are becoming less overtly "effects-y" with an emphasis on seamless realism. It also marks the first use of new technology called WAM!NET, a compressed video delivery service launched last year, which enabled round-the-clock post-production on rushes edited in Hollywood and digitally enhanced in London.

"Ridley (Scott) had a very clear idea of the effects he wanted," explains Robin Shenfield, Mill Film's managing director. "When he wasn't with us during post-production he'd look at a particular shot from that day's edit, pull off stills, then draw on these what he'd like, before sending them through to us here in London via the WAM!NET link."

Previously, a similar transfer of material could be done using transatlantic ISDN links, but the process was much slower. The speed and capacity of WAM!NET, which is majority-owned by MCI Worldcom, is equivalent to 90 standard ISDN lines. Around one gigabyte of material was transmitted daily between Hollywood and London in this way.

The film's centrepiece is the computer-generated Colosseum. For this, the team at Mill Film used footage shot in Malta where a two-storey set in the shape of a letter "J" was built to approximately one-third of the Roman amphitheatre's actual size. Additional tiers where then computer-generated using SoftImages 3D software and added to the live action shots with light and darkness adjusted. Compositing of all of these different elements was done using Inferno, a cutting-edge digital effects system made by Montreal-based Discreet Logic.

In a number of scenes shot against the Colosseum's exterior, Mill Film was again called on to flatten the building's curvature to make it look even bigger behind the foreground action. "We did consider building on actual model of the Colosseum, but creating it digitally had a number of advantages - notably, the ability to match the lighting of the interior with the exterior, and it was easier to populate it with computer-generated crowds," Shenfield says.

A key scene in the film involves the gladiators' arrival in the Colosseum for the first time, watched by a snarling crowd. The actors were filmed in a 360-degree sweep using Steadicam - a complex camera move for the effects team to match - while the 50,000 crowd was a complete digital creation. Mill Film vision effects compositor, explains: "We shot around 50 real actors from different perspectives then randomly sampled them, adjusting the colours of their togas to create the crowd." All of this then had to be choreographed to match the live action camera sweep. Finally, live footage of the gladiators was incorporated on top.

Mill Film also worked on enhancing the gladiators' tiger fighting in the Colosseum - bringing stunt doubles and real tigers closer together to make the drama more exciting and, in one shot, adding a computer-generated arm to suggest the gladiator is really fighting back. The tigers were shot against blue screen and relevant scenes recomposited to tighten the suspense.

Another set piece occurs earlier in the film with a major battle involving tens of thousands of Roman troops. The aim was to create "a Private Ryan effect" with a vast expanse of battlefield, thousands of troops, flaming arrows and explosions. For this sequence the background was filmed in three sections from three different locked-off camera positions to gain a panoramic backdrop. The action was then digitally enhanced - perspective was created by Mill Film which also transformed some 200 extras into thousands with the same technique it used inside the Colosseum.

Mill Film also played a role in helping Oliver Reed complete his scenes in the film - after his death. When he died, Reed had completed around 90 per cent of his scenes. There were a number of possible ways of doing this, Shenfield says. Eventually, however, a combination of pragmatism and subtlety won the day. The script was altered to remove Reed's character from the plot earlier. It was then left to Mill Film to produce eight shots featuring the actor posthumously.

Contrary to some reports, there was no digitally recreated Reed, Shenfield insists. Instead, footage of Reed from earlier scenes was manipulated. For one later shot his hair was altered, the colour of his tunic changed and beard trimmed before he was digitally inserted into a new setting using Inferno. In another scene, existing footage of Reed was combined with new footage of a body double. "It took a lot of effort to find the best shots of Reed to create an elegant solution," says Stanley-Clamp.

The end result is a good illustration of the direction in which film effects work is now moving. "New technological developments are focused on the creation of an increasingly seamless blend of computer-generated material and real sets," Shenfield says. "Camera moves are no longer a restriction - previously they could be difficult to match with computer-generated material. And work can now be done round the clock - even if the material is being cut on one continent and with effects work done somewhere else."