One thing is clear from Hollywood's latest attempt at generating photo-realistic human characters through computer animation: The technology has not reached a level at which it can capture the awe of a child. This is a fundamental problem for "The Polar Express," which tries very hard to be an instant-classic Christmas movie.

The glitch is in the eyes -- there's just no life behind them. In this picture, they're pixel-driven doll orbs without personality or presence. And CGI animators still can't seem to create a blink that doesn't look animatronic. It's enough of a distraction that anyone over the age of 10 or 12 will likely wonder why director Robert Zemeckis (who dabbled in animation with "Who Framed Roger Rabbit") didn't shoot the film live-action -- unless he just wanted to show off, as he clearly did when CGI-ing President Clinton into several scenes in 1997's "Contact" for no good reason.

But in spirit, "The Polar Express" comes very close to embodying the magic of the holiday it's supposed to celebrate -- if you can get past several more Zemeckis-isms.

Adapted from the children's book by Chris Van Allsburg ("Jumanji"), it's the story of a little boy (voiced by "Spy Kids'" Daryl Sabara) whose fading belief in Santa Claus is restored when an enchanted steam train pulls up outside his house on Christmas Eve and takes him to the North Pole. Onboard he befriends two other kids, the train's fatherly conductor (with the voice, face and motion-captured body language of Tom Hanks), and a mysterious hobo who rides on the roof (also Hanks, who plays six characters).

It's a 93-minute film adapted from a 28-page book, and the stretch marks are readily apparent in inscrutable and pointlessly perilous scenes involving a missing golden train ticket and in the overuse of roller-coaster point-of-view shots barreling down crazy train tracks.

But upon arriving in the fully realized, idyllic but highly mechanized, redbrick city at the North Pole, "The Polar Express" becomes a behind-the-scenes adventure that captures a certain wonder the computer-created characters cannot touch on their own. The kids get lost and soon discover a cool control center for elf operations (half high-tech, half industrial revolution), have a wild ride on the massive conveyor-belt system that carries millions of presents to Santa's sleigh, and find themselves tumbling head-over-heels into the jolly fellow's big red bag of goodies.

These scenes have video-game plot advancement, with the children defeating each level of challenge to advance to the next, but slowly the film does warm the heart with genuine Christmas cheer, even if it's not clear about its message. "One thing about trains," says the conductor cryptically, "it doesn't matter where they're going. What matters is deciding to get on."

Children will, no doubt, enjoy every minute of "The Polar Express," even if it never quite realizes a level of magical realism that will lift the spirits of more discerning grown-ups. It's an entertaining Saturday matinee, but the movie is too prefabricated (especially its handful of rather forced musical numbers), and the characters are too unnatural (the eyes, the cold tight skin of computer-animated human faces), not to mention unintentionally mechanical (many have that tell-tale CGI waddle rather than a natural walk).

Computer animators striving for realism may some day discover a technique for giving human faces and bodies the same authenticity as the wet snow clinging to the side of this movie's train cars. But in the meantime, no matter how good the stories may be in pictures like "The Polar Express," there will remain something significant missing from their souls.