How do you shoot a film like Lord of the Rings — which regularly has scenes of 10,000-Orc armies clashing with an equally massive sprawl of elves, humans and dwarves? Well, you could try to create computer-generated Orcs one by one, and figure out ways to animate them. But as it turns out, that makes the armies seem curiously stiff and scripted.

The solution? Use A.I. A New Zealand programmer for the movie created Massive, a program that gives each Orc a bit of artificial intelligence — and turns them loose. Each individual Orc tries to kill opponents and stay away from bad situations, much like the A.I. opponents in games like Quake or Half-Life. The result is a scene that has the same level of realistic chaos you’d get if you had 10,000 actual human extras acting it out:

Like real people, agents’ body types, clothing and the weather influence their capabilities. Agents aren’t robots, though. Each makes subtle responses to its surroundings with fuzzy logic rather than yes-no, on-off decisions. And every agent has thousands of brain nodes, such as their combat node, which has rules for their level of aggression.

When an animator places agents into a simulation, they’re released to do what they will. It’s not crowd control but anarchy. That’s because each agent makes decisions from its point of view. Still, when properly genetically engineered, the right character will always win the fight.

“It’s possible to rig fights, but it hasn’t been done,” [Stephen] Regelous [creator of Massive] said. “In the first test fight we had 1,000 silver guys and 1,000 golden guys. We set off the simulation, and in the distance you could see several guys running for the hills.”

It’s a neat examplar of what I call the new “military/entertainment complex.” It used to be that the military innovated — and perfected — the technology that was later used by entertainment (the way, for example, ballistics algorithms and computer circuity developed for warfare were later used for video games). That’s frequently reversed now. As Wired noted several issues ago, the best A.I. work now is in video games and movies; they innovate, and the government follows. It’s a side-effect of cheapening computer power and the infinite-monkeys rule: If you have a million geeks working on kewl stuff for fun, they’re quite often going to develop toys faster and better than even NASA.