Artist Spencer Tunick had an idea: Photograph nude people -- lots and lots of them -- in mind-boggling locations around the world. If this sounds like a gimmick, well, it is. But this gimmick actually turns out to be interesting. First, because the images Tunick comes up with are amazing. Second, because Tunick’s process succeeds in revealing cultural attitudes about art and what it means to be bare. "Naked World" is a documentary film about Tunick’s one-year trek to Tokyo, Paris, Sao Paulo and other cities to coordinate and photograph large groups of people in the nude. You can see it at the Indianapolis Museum of Art on Jan. 31 at 7 p.m. It’s free.