Step Up 3D

First off, the idea of the “Step Up’’ series is worth getting behind: cheaply made urban hip-hop dance parties with talented no-name casts and plots that are essentially dusted off Mickey-and-Judy let’s-put-on-a-show chestnuts. Dazzling narrative originality isn’t the point of these engaged B-flicks. The moves are.

That said, could Disney please get on the soul train for at least one of the films? The original “Step Up’’ (2006) starred Channing Tatum, and the novelty there was discovering the big lug could actually dance. Since then it has been one blandly interchangeable Caucasian lead duo after another, fronting a cast of African-Americans, Hispanics, Asians, and other ethnics who, in “Step Up 3D,’’ literally stand on the sidelines and cheer when Luke (Rick Malambri) and Natalie (Sharni Vinson) — both of them apparently the product of a shopping-mall eugenics franchise and both of them dull, dull, dull — kiss as they prepare to journey from New York to California. By train.

Obviously travel planning is not among the characters’ skill sets, nor is the ability to speak any language but Movie Cliché. (“The most important decisions in life are never easy,’’ intones the Yoda-like Ugandan dancer played by Keith Stallworth, at which point the screening audience I was with dissolved into laughter. Well, yeah.) “Step Up 3D’’ follows the old battle-of-the-bands story line, with the Pirates, Luke’s multi-culti crew (threatened with eviction from their Brooklyn squat, naturally), facing off against the mean old Samurais, who are also led by a scrawny white guy (Joe Slaughter, acting just as bad as he can) and who stand around with their arms folded a lot, yo.

But the dancing. As directed by Jon Chu and choreographed by a consortium of Jamal Sims, Nadine “Hi-Hat’’ Ruffin, Dave Scott, and brothers Richmond and Anthony Talauega, “Step Up 3D’’ is a riotous explosion of massed bodies, over-edited unto grand mal overkill but just as often allowed to group and disperse in thrilling patterns. Apparently there are a lot of “So You Think You Can Dance’’ finalists here, as well as gifted dancers with names like Ivan “Flipz’’ Velez, Oren “Flearock’’ Michaeli, and Ricardo “Boogie Frantick’’ Rodriguez Jr., none of whom will ever get the lead in a “Step Up’’ sequel as long as Walt’s ghost has anything to do with it.

There are dance sequences in shallow pools of water, the footstomps sending up joyous sprays, and a ridiculous but fun number with the Pirates wearing LED uniforms. There’s even a delightfully simple single-take sequence where the geeky comic relief (Adam G. Sevani) and his plain-Jane girlfriend (Alyson Stoner) hoof it down the street to Fred Astaire singing “I Won’t Dance,’’ their steps referencing such classic MGM musicals as “Singin’ in the Rain’’ and “It’s Always Fair Weather.’’ (Psst, kids, you can find those movies on Netflix and they’re really good.)

Here’s the caveat: Everything’s in 3-D. It works and it doesn’t. Chu spends far too much time throwing dancers and their limbs at the camera — though there is that one scene where a female Samurai finger-tuts her way right into the center of your cerebral cortex — and the technology can’t keep up with the moves. The busy camerawork, flailing limbs, and reflective surfaces defeat the eye’s ability to process visual information and too much of the choreography judders like a video game on an undercooked computer system.

Every now and then, though, “Step Up 3D’’ breaks out of its morass of idiot dialogue, institutionalized media racism, and hectic head-spinning, and it soars. You see the potential for movie dance unbounded by the flat 2-D scrim of the screen, and you see how a forward-thinking director — it might even turn out to be Chu someday — could become a Busby Berkeley for the 21st century. In the meantime, I dare Disney to put this series back in the black.

Ty Burr can be reached at tburr@globe.com.