From a technical standpoint, the summer's most difficult movie to make wasn't "Pearl Harbor," "Jurassic Park 3," nor "Planet of the Apes."

Instead, it was one that received a fraction of the marketing fanfare of those three—and, as a result, a fraction of the box office: "Final Fantasy: The Spirits Within," now available on DVD.

The reason the futuristic sci-fi film was such a challenge is that it's the first animated movie to seriously attempt realistic human characters. On that score, many critics called it a success.

"One of the reasons people have been avoiding it before is that we look at ourselves in the mirror every day. We know exactly what human beings should look like," says co-director Motonori Sakakibara. "When the minor details are off in the human face, it looks totally foreign to us. In that sense, compared to animals, we really had to pay extra attention to the most minute details."

More to the point, while the "JP3" dinosaurs may have wowed audiences, nobody really knows what a dinosaur looks like. Or how they walked. Or how they pursued their prey.

But humans, we know pretty well.

And getting the characters in "Final Fantasy" (2001; PG-13 for sci-fi action violence; 1 hour, 46 minutes; $29.95) as close as possible to the real thing was a primary mission.

The movie, which earned an OK $32 million at theaters, takes place in 2065 after a meteor has struck Earth and the planet is infested with alien creatures. The best chance at survival lies with a beautiful scientist, Dr. Aki Ross (voiced by Ming-Na).

She is aided in her efforts by Dr. Sid (Donald Sutherland) and Capt. Gray Edwards (Alec Baldwin), who leads the Deep Eyes Military Squadron.

But what really makes the movie isn't the storyline, which has been done dozens of times before on television and in earlier movies. It's the digital animation.

Fortunately, the two-disc DVD plays up that aspect, with a making-of featurette, and two feature-length commentaries, including one by Sakakibara.

The Japanese-speaking filmmaker, who uses a translator, figures "Final Fantasy" came to within 70 percent of creating a realistic animated human. While that may not seem like much, it's a huge stride from past movies that could at best manage a human from a distance—often in a dark scene—without many details (remember the Propeller Guy in "Titanic"?).

"Right now, with the technology we have today, we can actually do the remaining 30 percent—but only with a still photo or still image," Sakakibara says.

Making those images come alive—with details like muscle movements, wrinkles and hair, and getting light to bounce off the subjects just right to make them look realistic—will take some work.

"The hardware to do that would need to improve quite a bit," he says.

Does Sakakibara plan to take filmmaking to that next step? It's possible, but it would be a lot of work. "Final Fantasy" was a computer-generated project four years in the making.

"We're considering different story ideas, one of which would allow us to utilize the technology and the knowledge we have.