Of the year’s 10 top-grossing films, three fit what the Academy celebrates via its 13-years-young animated feature category: “Despicable Me 2,” “Monsters University” and “The Croods.”

But then, what do you call “Iron Man 3,” “Oz the Great and Powerful,” “World War Z” and “Gravity”? Each of those more-digital-than-not blockbusters could be “animated” enough to fit the Acad’s definition, “in which movement and characters’ performances are created using a frame-by-frame technique.”

“Gravity” makes an especially intriguing case, since Sandra Bullock and George Clooney’s faces are often the only practical element that appears onscreen. Director Alfonso Cuaron has repeatedly described the innovative process they developed to create the film as being akin to that of making an animated movie. Only after the team had spent 2½ years nailing down the lighting, angles and character animation in a detailed previsualization did it reverse-engineer a way to shoot footage of the actors.

At last month’s VES Summit, Bill Kroyer pointed out the expansion of animation techniques into traditional filmmaking — an evolution that has been under way since such half-toon hybrids as “Song of the South” and “Mary Poppins,” well before the advent of computer-generated imagery.

“I believe every year we’ll see increased uses of animation techniques in filmmaking,” Kroyer says. As governor of the Academy’s short films and feature animation branch, Kroyer faces the unusual challenge of having to decide where to draw the line — though he believes the success of “Avatar” and “Life of Pi” illustrate that moviegoers aren’t the slightest bit distracted by how the lines are blurring.

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“The only people who have to worry are those of us at the Academy who reward the work; the audience can just enjoy it,” he says. “At the end of the day, it’s only us who has the problem (of deciding whether something qualifies as an animated feature). Because man, I’ll tell you, it’s pretty hard.”

This year, Sony Pictures Animation submitted “Smurfs 2” for consideration in the category — a film in which the animated blue-man gang coexists with flesh-and-blood actors onscreen. Back in 2009, however, Paramount didn’t even bother with “Where the Wild Things Are,” despite most of the characters being animated.

Although Academy’s rules stipulate that “a significant number of the major characters must be animated, and animation must figure in no less than 75% of the picture’s running time,” Kroyer says. “We’re long past the days of getting out the stopwatch and having to time the amount of animation in a movie, the way we did with films like ‘Stuart Little.’ ”

Now, it’s a question of whether the filmmaker considers the film to be animated, with the distinction often drawn between whether the animation is intended to look “realistic” (no matter how fantastical the creatures) or more stylized and “cartoonish.”

So, don’t expect any Marvel or DC entries in the category any time soon — at least, not any of the so-called “live-action” ones. But don’t be surprised if that changes down the road, especially now that the Academy has expanded the nominating process for the category to the entire membership.

In the past, members of the branch attended screenings of all eligible toons in November and voted to determine the noms. Now, any Academy member can participate, evaluating the contenders via DVD screener — a move that brings animated features in line with other categories.

And because the nominating members are expected to view all the animated contenders, don’t be surprised to find a few non-blockbusters among the final five.

“This is absolutely not a group that goes by box office, as you can see from their history, picking Miyazaki and ‘The Illusionist,’” Kroyer points out. “They are really looking for the thing that they as lifelong professionals respect and respond to.”