Martin Scorsese’s “Hugo” is a children’s film for grownup film buffs.

It’s a charming and quite gorgeous exercise in the few corners of the medium in which the Oscar-winning filmmaker has next to no experience — children’s stories, comedy and 3-D.

And even though it is too long and the master has yet to develop much of a comic touch, this adaptation of Brian Selznick’s “The Invention of Hugo Cabret” is a stunning exercise in 3-D and a delightful celebration of Scorsese’s lifelong love of the movies — something he, like Hugo, developed in childhood.

Hugo (Asa Butterfield) lives in the bowels of a Paris train station in between the World Wars. He is an orphan who hides out, carrying on the job a drunken uncle left him with — servicing the huge clocks there. He slips in and out of the station, getting by on stealing food and drink, hoping not to be noticed by the station inspector, Gustav (Sacha Baron Cohen).

Hugo’s a tinkerer, something he picked up from his late father (Jude Law). His favorite project is an old clockwork automaton, a wind-up man he tries to fix with parts stolen from the toy shop run by a cranky old man played by Ben Kingsley. When the old man catches Hugo, he seizes the boy’s notebook, full of his father’s drawings and fixes for the automaton. Hugo must work in the shop to win back the notebook.

Isabel (Chloe Moretz) calls the old man “Pappa Georges,” and even she finds Hugo dubious company.

Hugo must win her over, elude Gustav and get back the notebook.

“Hugo” is the best-looking 3-D movie since “Alice in Wonderland.” The director peoples the set with character players (Richard Griffiths, Emily Mortimer, Christopher Lee), and sets in motion subplots about the lonely Gustav, the fate of Hugo’s drunken uncle (Ray Winstone of “The Departed”) and clues to the automaton’s and Pappa Georges’ past.

Moretz, slinging an English accent, is her usual delightful self. Cohen takes a number of scenes to make any sort of comic impression. And Kingsley makes the journey from ogre to charmer in his usual winning fashion.

But the story — period details and mysteries notwithstanding — is too slight to support this length.

Still, movie buffs, especially fans of early cinema history, will be transfixed by scenes in the latter acts — movie-making, as it was being invented.