Christmas has always been magical. 

But creating “Arthur Christmas” -- the computer-generated 3D comedy that opens Wednesday and features a high-tech Santa capable of delivering toys in a Millennium Falcon-like spaceship -- was itself something of a small miracle, the special effects gurus at Sony Pictures Animation said.

“It was a lot of very long days,” lead animator Josh Beveridge told FoxNews.com. “It started out as nine hour days, and then eventually became a series of very long twelve hour days.”

Beveridge spent over a year in Bristol, England, where he worked with three other lead animators and a special effects supervisor to make the “Arthur Christmas” characters come to life. “He was like a satellite with a team of twelve people on the other side of the world, dialing in by video conference call,” explained first-time director Sarah Smith. “It was a big collaboration.”

Smith wanted to have her film rich with detail, which taxed Sony’s block-long computer room to its limits. “We had shots that took 24 hours per frame to render,” Smith said of the process; some scenes required almost month to make just one second of film. “There’s so much detail in those scenes that the computer is doing gigantic calculations in order to render that shot.”

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“We use a Linux platform,” Beveridge explained. “Almost anything that we want to do in CG, we can -- it’s just a matter of rendering time.”

The incredible computing time the film required hearkens back to the very early days of CG thirty years ago, Smith told FoxNews.com. “Computing power has advanced since then ... but so has the ability for the team to build more visual information in the shots.”

“Arthur Christmas” tells the tale of the multi-generational Claus family, which mothballed the old family sleigh in favor of the high-tech S1, a mile-wide spaceship with stealth cloaking technology and a million elves, who work in “Mission: Impossible”-style teams of three to deliver presents in just 18.14 seconds.

The film is Sony Pictures Animation’s first collaboration with Aardman, the landmark British animation company best-known for the stop-motion films “Chicken Run” and “Wallace & Gromit: The Curse of the Were-Rabbit.”

The Claus family consists of Santa and Mrs. Santa; Santa’s father, Grandsanta, who may still have a few tricks up his sleeve despite his advanced age; alpha-male son Steve, who is more concerned with efficiency than emotions; and the film’s hero, son Arthur, whose earnestness and wonder is matched only by his awkwardness and bad skin.

Arthur Xmas

“The Clauses are a little bit like the British Royal Family,” Smith said. “Arthur would be a little bit like Prince Edward since he’s the one who didn’t go into the army. Steve’s character is a little like Price Charles, in that every year, he’s thinking he’s going to become [king] and it doesn’t happen.”

Wanting to bring the traditional charm of Aardman’s characters to the world of CG, Smith spent over six years perfecting “Arthur Christmas.” 

“It was ridiculously ambitious,” Smith admits of the laborious process. “It’s a little like childbirth: If you really knew exactly what was going to be involved, you probably would never start.”

The ability to create virtual sets allows wonderful creativity, but it’s deceptively challenging. Despite the computers creating the final film, animators still draw everything. 

"It comes down to human labor, building every single thing that you see in every frame -- it’s not like they magically push a button and it happens," Smith told FoxNews.com. "Somebody has to model it and texture it and so on. CG animation is a seductive and dangerous thing, because you can theoretically do everything -- but you're limited by the human resources of your team.”

Of the many involved sets, Mission Control at the North Pole was the most challenging. “I think we were all pretty terrified by some of the render times,” said Smith. "They told me that there were shots that were taking three weeks to render. At the end of the process, we were terrified that there were some shots that weren’t going to even make it into the movie, because they were so complex to produce!”

But of all the technological achievements of “Arthur Christmas,” Smith is most proud of Arthur’s Christmas sweater. “I wanted it to have this really big, chunky effect, and (the animators) would kind of look at me and go, ‘Heavy knitwear? You have no idea how difficult that is to create. That’s like what water and fur used to be for CG.’” Smith said.

Now that “Arthur Christmas” has wrapped, Smith is taking a well-deserved break to work on her next magical venture.

“I had a baby in the middle of making the movie, so I’m spending time with her now -- she’s my new project!”