This animated film, which opens Friday, features appealing characters, an interesting story, and highly innovative visual effects. Its principal weakness, such as it is, is that it goes by too fast and ends too soon.

Think life looked hard a millennium from now in Battlefield Earth? In Titan A.E., the 31st-century Earth is not merely conquered but destroyed; this happens in the film's first few minutes. (A.E. means "After Earth.") As the alien Drej attack, human survivors flee the planet. A young boy named Cale is separated from his father, inventor of a mysterious spaceship called the Titan.

A ragtag band of heroes

The story picks up 15 years later. Humans are refugees and drifters, looked down upon by self-respecting alien races and apparently heading for extinction. Cale (voiced by Matt Damon), who's never seen his father again, works on a ramshackle salvage station. He's a young man with a not-very-good attitude.

But he may also be humanity's last hope. The spaceship Valkyrie arrives, captained by Korso (Bill Pullman), one of Cale's dad's former associates, who reveals that the young man's hand contains a map that glows when activated and which points toward the hiding place of the enigmatic Titan.

Before long, Cale is off with Korso and his crew, including the beautiful Akima (Drew Barrymore), a highly skilled pilot whose first impressions of Cale are not favorable. The others on board are aliens of several species. While searching for the Titan, they must contend with the Drej, who also wish to obtain the spaceship and who remain determined to eliminate the "human threat."

The plot can be facile; Cale's escape from a Drej ship makes one wonder about the aliens' security techniques. But suspense builds nonetheless, as appealing characters are thrown into intense situations that are also visually spectacular.

Strange universe

The film has a very unusual look that's derived from combining relatively flat animated characters with deeper, computer-generated backgrounds. This makes for interesting contrasts, though on occasion the shift between styles and techniques becomes distracting. The Drej and their queen are impressively implemented as beings of "pure energy."

The backgrounds sometimes veer toward surrealism, yet exhibit impressive, realistic detail. Particularly noteworthy is the planet Sessharim, with its explosive "hydrogen trees." A less successful sequence occurs in the (equally fictitious) Ice Rings of Tigrin, which look somewhat like holiday ornaments. The Gau, beak-mouthed natives of Sessharim, are eerily intimidating.

The voice acting is strong overall. Barrymore shines as the tough, smart Akima. Damon is reasonably convincing as Cale, aided perhaps by the actor's resemblance to the character. John Leguizamo is noteworthy as the roundish Gune, a brilliant navigator, while Janeane Garofalo is amusingly irritable as Stith, a doglike weapons expert.

The score features music by various rock or pop bands, including Lit, Powerman 5000, Electrasy, and Bliss. These selections are adequate but generally not memorable. More interesting is the theme that accompanies the Drej, provided by chanters from the central Asian region of Tuva.