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“Spider-Man: Into the Spider-Verse” follows the adventures of an Afro-Latino teenager, Miles Morales, who has been bitten by a radioactive spider in New York City and joins forces with other Spideys from alternate dimensions. It’s one of the animation surprises of the season: both a box office hit and a critical favorite.

One reason is the fresh animation style. Many recent American animated features look homogenized. More powerful computers and software have made it possible to produce intricately detailed backgrounds and characters: You can see every leaf on every tree and every stitch in a sweater. But characters of all shapes and sizes seem to have very similar walks, runs and expressions.

“Spider-Verse’s” three directors — Bob Persichetti, Peter Ramsey and Rodney Rothman — wanted to move away from that sameness, in part because Miles is so unlike the Spider-Man fans know from the live-action movies.

“That made it doubly important for the film to look new, so viewers would feel like they’re seeing Spider-Man for the first time,” Ramsey said.

”In CGI films, many things you see on-screen are the result of the desire to automate the process: simulations for hair, cloth, wind, rain, etc.,” Persichetti explained. One of the first decisions they made was to eliminate motion blur. In live action, some movements are so fast the images appear smeared in individual frames of film. Computer animation can simulate the effect, giving the imagery a smoother feel; eliminating the blur produced more staccato accents.

The artists made a bigger decision to break with the way most computer-animated motion is achieved. Usually movements are created by advancing the image — say, a character raising his arm — in each frame, 24 times per second. It’s called “animating on ones.” The resulting motion is fluid and smooth, but it can look too regular, even stolid. Having worked at Disney, Persichetti wanted to borrow ideas from hand-drawn techniques.

In traditional animation, much of the movement is done “on twos”: A new drawing is made or the image shifted every second frame. Using animation on twos gave the artists more control over the speed and power of the movements. Working on ones and twos let the artists vary the rhythms of movements. When Miles dashes through a snowy forest, his run is animated on ones to emphasize his speed. When he stumbles and falls, he rises on twos as he slowly pushes against gravity to get back on his feet.

The animation also allows the filmmakers to stress dynamic poses that telegraph how Miles is leaping and spinning through Manhattan. Screenwriter/producer Phil Lord explained: “Telling stories in sequential art is all about the key pose and going from pose to pose and frame to frame. Stan Lee laid it out in ‘How to Draw Comics the Marvel Way.’ ”

One of their directives was that “if it looks and feels like something from an animated film, it’s not our movie,” Persichetti said. Miller concluded: “The technical challenges ended up being much more complicated than just doing the animation on twos. But the techniques gave the film a signature look that emphasized the individual images.”

“From the beginning,” Miller said, “we wanted someone to be able to freeze any frame of the movie and have it look so good, they’d want to frame it and hang it on the wall.”