"Step Up 3D" does 3-D right, despite the corny story line

Step Up 3-D is, in one significant respect, a step up.

That is, in contrast to the recent spate of postproduction 3-D conversions (see The Last Airbender, see Clash of the Titans), this one actually looks good.

Conceived and shot as a 3-D dance spectacle with specialized cameras and technology, the film has dancers spinning and bobbing, popping and locking, jumping off the screen. There's even a Busby Berkeley-inspired number where the point-of-view goes overhead, capturing a crew of street dancers spinning crazily below.

The images are vivid, the actors (if you want to call them that) stand out (none of those fuzzy dimensional shadows), and there are cool stereoscopic effects, like the spray from an Icee straw sending a stream of giant, artificially-colored bubbles out into the audience.

That's the good news.

The bad news: This second sequel in the hit hip-hop series boasts more clichés than you can shake one of those Icee straws at (follow your dream, believe in yourself, it's the journey not the destination, how could you do that to us?). And while director Jon M. Chu's acrobatic cast proves adept at moonwalks and break-dances - and even tangos and tap - not a one displays anything even closely approximating charisma.

Moving from Baltimore, site of the first two Step Ups, to New York, and foisting the first sequel's nebbishy teenage sidekick, Moose (Adam G. Sevani) into a lead role, Step Up 3-D is essentially a series of big, busy production numbers beaded together with cheesy melodrama and scenarios out of Rent. It's also one long commercial for NYU, the school where Moose and his childhood pal Camille (Alyson Stoner) are now wide-eyed enrollees.

Luke (Rick Malambri) is a sensitive filmmaker and dancer who hosts a "pseudo family" of misfit hoofers in his sprawling Brooklyn loft - a loft that evil bankers are planning to foreclose on. Natalie (Sharni Vinson) is a lithe and limber sensitive gal who claims to be broke, and to whom Luke offers a bed and some Urban Outfitters furnishings.

Luke's gang, dubbed the Pirates, is gearing up for the World Jam - an epic dance-off with a cash prize that could help with those pesky mortgage payments, and which would give 'em their moment of So You Think You Can Dance glory. The Pirates' archenemies: the Samurai, a rival gang of dancers led by the sneering Julien (Joe Slaughter).

To tracks by T-Pain and Jay-Z, MIMS and Major Lazer, the Roots and Rye Rye (and some Bach and Benatar thrown in for good measure), the various dancers dance, and the various conflicts play out. Luke and Natalie look good until Natalie does something bad. Moose and Camille look good until Moose fails to show for the Halloween party - he and Camille were going as the Olsen Twins.

Aimed at teens and tweens, the almost-squeaky-clean Step Up 3-D shamelessly piles on the corn, stacking it so high that it's bound to tilt over and collapse. But at least it goes tumbling down in three dimensions. And the dancers go tumbling along with it - tumbling right at ya.EndText