Before Steve Carell and director Robert Zemeckis went forward with Welcome to Marwen, their new movie about artist Mark Hogancamp, they first wanted to meet with him to get his OK.

Hogancamp is publicity-shy and understandably wary of outsiders. His work involves using action figures and dolls to construct miniature worlds, a process that’s helped him heal psychologically from a near-fatal beating, incurred when Hogancamp told some strangers at a bar that he liked to wear women’s shoes.

Would he accept these Hollywood big shots into his life?

Zemeckis got a clue when he entered Hogancamp’s house and saw collectibles from Zemeckis' beloved Back to the Future trilogy prominently on display.

“He’s a fan,” said Carell, who stopped in Philadelphia with Zemeckis last week. “He’s got it all.”

“He had his Marty McFly figures, his Doc Brown figures, and they were right there front and center," Zemeckis said.

It was a multilateral admiration society. Carell and Zemeckis each became intrigued with Hogancamp’s story and his work independently, viewing the documentary Marwencol, which chronicles the Upstate New York artist’s unique, outsider work.

Hogancamp built a replica WWII Belgian town in his backyard and posed the action figures and dolls in ways that told a story — featuring Hogancamp’s heroic 1/6 scale alter ego, “Hogie.” The dramas fictionalized and reimagined his assault in a way that helped him deal with the trauma he’d suffered. His photographs of these scenes became celebrated works of art.

“Obviously, we both loved the story of Mark’s journey, and the powerful theme of the healing power of artistic expression. On top of that, I just was fascinated with these elaborate stories that were going on in his imagination, and I thought, that’s something you can do in a movie,” Zemeckis said.

The director also saw it as a chance to further the motion-capture technology he helped pioneer in movies like The Polar Express. He uses sensors to capture the movements and expressions of an actor like Carell, then adds layers of animation to produce a finished image. It’s ideal for what Zemeckis wanted to do in Marwen, bringing Hogancamp’s action-figure fantasy realm to cinematic life via performance capture in collaboration with Carell, Janelle Monae, Leslie Mann, Diane Kruger, and others.

Carell does plenty of plain old live-action acting, too, and to that end, he found his meetings with Hogancamp invaluable.

“When I met Mark, I got a better sense of the type of man he is, a lovely human being, and that was the most important aspect of my work here,” Carell said. “There is also the time we spent corresponding since I met him. He’s private, but he’s also funny and warm and has a great sense of humor about his world that was inspiring to me. He gets that this is offbeat and that from an outsider’s view, it must seem like a strange thing.”

Maybe not so strange to Zemeckis, who knows a thing or two about creating imaginary worlds with scale models. You see one of them in Welcome to Marwen — Mark builds a time machine out of a familiar-looking DeLorean that leaves a trail of fire behind when it shoots into another dimension.

Back to the Future director Zemeckis remains committed to bringing the future closer by pushing movie technology “to stretch the art form so that you can do the things you can’t do in any other medium.”

He’s constantly refining and improving motion capture, and also to an extent defending it. There are those who worry it will supplant human performance, but Zemeckis isn’t one of them.

“The way to look at it and to feel comfortable about is to think about music. We can digitally record and reproduce exactly every single sound a philharmonic orchestra can produce. But we’re always going to start with the warmth of the human performance. Someone has to put their fingers on the keys. So that’s what’s happening with images now. You still need that human performance to drive it.”