While the likes of Pixar and Disney transformed animation using CGI principles and George Lucas and Steven Spielberg leveraged ever-more believable CGI and compositing work into their films, it was Peter Jackson who truly propelled the technology into its next stage by incorporating artificial intelligence into the huge battle scenes that featured throughout The Lord of the Rings trilogy.
Jackson wanted software that would allow hundreds of humans and orcs to interact naturally without the need to animate each character individually. Each soldier had to fight the right enemy and behave as a character would in battle. The answer came via a developer named Stephen Regelous, who created Massive. This program allowed developers to quickly create thousands of individual characters, each of which responded differently to its surroundings.
The reactions of every character affected other characters in turn, changing how they acted and allowing motion-captured animations to create a realistic scene. Without Massive, the battle scenes of Middle Earth would have been near-impossible to create. An apocryphal tale recalls how Massive's AI was so sharp that when confronted with thousands of baying orcs, the armies of Middle Earth quite sensibly turned tail and ran away in terror. In reality, a bug in Massive caused the glitch, but the other story is an excellent anecdote.
Blending fact and fiction
Most will cite the likes of Toy Story, Shrek and The Lord of the Rings trilogy when thinking about CGI, but the real skill of special effects studios is blending real-life footage with elements of CGI for a rich, believable tapestry. Green-screen compositing and rotoscoping effects – as seen in Sin City, 300 and A Scanner Darkly – have blurred the line between reality and fiction. In some cases, the effects have been purposefully 'virtual'; for example, A Scanner Darkly used the Rotoshop digital technique to achieve a classic look.
The recent blockbuster Iron Man clearly needed to use huge elements of CGI, but for certain passages of the film it's hard to tell what is composited and what is real life footage. The Iron Man's cybernetic costumes started life as hardware, but Stan Winston Studio built practical versions of all the suits, along with those worn by Iron Man's nemesis, Iron Monger. These suits were used during the live shoot, but the physical props were replaced with digital versions when needed.
Visual effects giant Industrial Light and Magic (ILM) did the bulk of the compositing and animation for the film, including building the virtual suit. Because ILM was also responsible for Transformers, it had experience of rendering metal objects. But Iron Man was a different kind of movie: "The designs needed to be believable," says digital model supervisor Bruce Holcomb, who moved onto Iron Man from Transformers. "For Transformers, we constructed alien robots with lots of parts, and the visual confusion added to the enjoyment. Iron Man was more about design. The suits didn't have ambiguous parts moving for no reason."
Creating by removing
Just as it can add elements, CGI can also remove them. The 2007 release I Am Legend needed to depict a post-apocalyptic New York City. Director Francis Lawrence didn't want an obviously computer-created set, so he blended CGI with the motion capture.
Special effects were used to dilapidate NYC, remove stray New Yorkers from windows and stall moving cars seen in wide shots. "We didn't want to make an apocalyptic movie where the landscape felt apocalyptic," said Lawrence. "There's something magical about an empty city, as opposed to it being dark and scary."
Whether adding fantastical characters and scenery, removing human elements or simulating epic battles, CGI is now a staple element of modern movie making. It may seem odd that the common tools of the trade are commercially available software packages, but this only goes to show that the real skill of special effects lies in the artistic expression used rather than the sheer processing power of the technology.
The Best Visual Effects Oscar, established properly in 1996, sets out to reward "the artistry, skill and fidelity with which the visual illusions are achieved". As a result, even in today's world of super-powerful computers, the award is still won by skilled creatives rather than nimble programmers.
Liked this? Then check out Populous to The Sims: a history of playing god
First published in PC Plus Issue 280
Sign up for the free weekly TechRadar newsletter
Get tech news delivered straight to your inbox. Register for the free TechRadar newsletter and stay on top of the week's biggest stories and product releases. Sign up at http://www.techradar.com/register