For the longest time, special effects in movies depended on the elements of stagecraft, using makeup, lighting, and tricks of perspective to fool the audience's eye. Putting a camera into the theatrical realm actually made things easier, because the director could control the exact angle the action would be seen from and use film-editing techniques to assemble scenes that could never be staged live. It's easier to fool a camera than a big room full of people watching a play.

But once filmmaking entered the digital realm, most of the conventions of making films became obsolete, although it has taken some time for the technology to mature and for the movie industry to realize what it all could mean. There's certainly been a lot of digital work incorporated into films during the past two decades, but when people look back, 2004 will stand out as the year when the balance really began to shift from real-world to virtual production.

What prompted these thoughts was my attending a showing of Sky Captain and the World of Tomorrow, which is notable for being almost entirely created in a computer. Only the actors and a few minor props were actually filmed; everything else was composited-in graphics. How was the movie? Well, my inner 10-year-old would see it again but my outer 40-year-old won't take him. It's fairly watchable for most of its length, then starts to nosedive into tediousness, perhaps in part because you know consciously (and sense unconsciously) that everything is a little more fake than usual.

That overwhelming awareness of the artifice in filmmaking might actually lead to a change in the types of movies made. It's one thing to see an action film from the old days, made with stuntmen and pyrotechnics, but there's not much meat in a movie where you know some actor is just spinning around in front of a blue screen. The story line and performance quality have to be exceptional to bridge the increased credibility gap. I think of this as the Matrix Reloaded syndrome, because while watching that for the first time it occurred to me that the spectacular fight sequences were very dull and the only interesting scenes were the conversations that explained more of the concepts behind the Matrix world.

Which is not to say that a virtually en-hanced film is always worse than the real-world equivalent. If I were choosing a remake of Akira Kurosawa's Seven Samurai to watch, I'd pick the animated A Bug's Life over The Magnificent Seven every time. Unless you like dusty vistas, all the latter has to recommend it is a great soundtrack and occasional flashes of acting from Steve McQueen and Yul Brynner. It's a very stagy movie. A Bug's Life is better at immersing you in a story.

By the way, it wasn't Sky Captain that made me pick 2004 as a pivotal year; it's the fact that most of the trailers that ran before it were for upcoming computer-made films like Shark Tale, Team America: World Police, The Incredibles, and The SpongeBob SquarePants Movie (which could be the best of the bunch). Admittedly, the choice of coming attractions shown reflects the audience demographic at Sky Captain, but that's still a lot of computer-made films in one season. And who knows what subtle digital techniques were used to tweak even the most traditional of modern real-actor movies?

One other upcoming digital film that wasn't previewed at this screening is The Polar Express, which will feature actors that have been animated over, a technique that used to be called rotoscoping. In this case, it is combined with the techniques of motion capture originally developed for video-game production. People get dressed up in body suits covered with little white dots and are filmed moving about. Computer animators use the footage to generate realistic movements. The people behind Polar Express have refined the process even further and are bold enough to call it "performance capture".

What's the difference between capturing motion and performance? In theory, it comes down to the number of white dots on the body suit, the resolution of the data that's being captured. In this case, according to the October issue of Vanity Fair, the actors wore some 200 dots, three-quarters of which were on their faces. Instead of animators struggling to make realistic facial expressions (or fudging the issue by concentrating on nonhuman characters), a digital face mask can just be attached to the dots, which in turn carry the record of the subtle movements actors use to portray characters.

Tom Hanks actually provided the movements for three people in Polar Express (which is nothing Alec Guinness didn't do in the old days of Kind Hearts and Coronets). Hanks avoided spending a lot of hours in the makeup chair and he didn't have to film retakes if something looked fake--that's a programming problem.

As this technology filters down to the mainstream (like video-editing software already has), a whole lot more people are going to be able to make films. What's more, they'll be able to realize their visions more fully, for better or worse. Even low-budget filmmakers in the mould of Ed Wood Jr. or Roger Corman will be able to create effects that look believable. The question is, Will they end up making good movies? Poor special effects can usually be ignored in an otherwise good film, but great effects can't save a badly done effort. I expect we're about to endure a flurry of weak films built with great technology, and then all the excitement over the new toys will die down. Like all the other technical innovations in the history of cinema, after a while digital processes will just be another set of tools to be used when they're useful and ignored when they won't add anything.