Saturday could end up being the most-documented day on the planet.

At least, that's the hope of the forces behind Life in a Day. On Saturday, people all over the world are invited to pick up a video camera, film something they consider to be a snapshot of their life and upload it to YouTube. The most compelling submissions will be woven together into a full-length documentary film.

The end result will have its premiere screening in January at the 2011 Sundance Film Festival. It also will be available on YouTube in 2011.

The goal of the Life in a Day project is to create a user-generated experimental documentary that will serve as a kind of visual time capsule for future generations.

The videos can be about anything that the people making them find meaningful, interesting or important. They can be about the ordinary or the extraordinary. Suggested themes people can work with include something they love, something they fear or something that makes them laugh. The aim is to record some aspect of life that conveys what it's like to be alive in that particular place and time.

The organizers also are encouraging people to organize "film-ups," where friends meet up and film together.

Guiding the project artistically are director Kevin Macdonald ("The Last King of Scotland," "Touching the Void") and producer Ridley Scott ("Black Hawk Down," "Thelma & Louise," "Robin Hood").

Mr. Macdonald will edit the videos chosen into the full-length film. He said he wanted to "make a film unlike any film that's ever been made before" in a YouTube video explaining the project.

"My aim is to make a film that is a snapshot of life on Earth during one 24-hour period. ... Ultimately, this is a unique experiment in social filmmaking and a time capsule that will forever tell future generations what it was like to be alive on July 24, 2010."

Videos must be filmed on Saturday. They can be uploaded to YouTube between July 24 and 31.

There's no cash prize for the winning entries, but those whose footage is used will get a co-director credit. Twenty contributors will be invited to Sundance for the premiere.

People must be at least 13 years old to enter. There's no limit to the number of clips an individual can submit.

Submissions don't need to be edited -- they're looking for raw footage to work with. People being filmed do need to give their permission, and filmmakers should try not to use music, because of copyright issues.

The videos submitted will begin to post on YouTube in August. All submissions will be featured on a YouTube Gallery later this year.

For details on entering the Life in a Day competition, visit YouTube's Life in a Day channel, www.youtube.com/lifeinaday.

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