Director Steven Spielberg set an ambitious goal for himself and his “Ready Player One” VFX team: weaving viewers in and out of a virtual world within the storytelling parameters of a traditional film. The movie, released by Warner Bros. in March, is one of five up for a visual effects Oscar this year.

To adapt Ernest Cline’s 2011 young adult novel about kids who escape a dystopian 2045 by immersing themselves in a massively multiplayer online simulation game, the talents of no fewer than 11 tech firms were required. The bulk of the work fell to three companies: Digital Domain, Industrial Light & Magic and Territory Studio.

The plot focuses on teenage gamer Wade Watts (Tye Sheridan), who, like most of the underemployed population, spends what seems like every waking hour role-playing inside the virtual world called Oasis. In the game, he competes in a series of puzzles, the successful completion of which will result in ownership of the Oasis itself.

The film’s two distinct worlds — a dingy, overcrowded reality in which people live piled on top of each other in housing units called stacks, and the vividly extravagant Oasis — provided a natural division of labor for the effects teams: Digital Domain managed previsualization for the entire film, handled motion capture and virtual sets and also created the real-world effects. ILM conjured the CGI for the Oasis; Territory Studio created graphics that bridged the two worlds — seen mainly on monitors and in HUDs, or heads-up displays (transparently shown information that doesn’t require viewers to look away from their reference point on the screen).

“Eighty minutes of the [140-minute] film — the length of an animated feature — takes place in the Oasis,” explains ILM visual effects supervisor Grady Cofer. “It was daunting, world-building on a massive scale.” He notes that the Oasis “travelogue” included 60 distinct environments, “every aspect of which had to be designed and populated with interesting characters.” Cinematic references abound, with cameos by the Iron Giant, King Kong, Batman and the dinosaurs of “Jurassic Park,” along with props like the flying DeLorean of “Back to the Future” and Ripley’s pulse gun from “Aliens.”

“For pop culture fans, of which I’m a card-carrying member, it was a dream come true — nearly 1,000 assets that we created,” Cofer notes. In all, ILM contributed about 900 finished shots via its headquarters in San Francisco and studios in Vancouver, London and Singapore.

Digital Domain delivered more than 300 finished shots, according to visual effects supervisor Matthew Butler (with Territory coming in at 260). In addition to the real-world effects, under the direction of virtual production supervisor Gary Roberts, Digital Domain set up a motion-capture stage in London, created 14 hours of motion capture, processed it and sent it to ILM to use in the Oasis.

A proprietary aspect of DD’s motion capture is its use of game engines to power real-time virtual sets. “Because everything lived in a game engine, we were able to have Steven put on a headset and scout the sets and make adjustments,” says Digital Domain previsualization supervisor Scott Meadows. The actors could also put on headsets to inform their performance, and the sets were displayed on reference monitors as well.

“Getting the performances right was very important to Steven,” says Roberts. “He was cutting back and forth between the avatar and the live-action actor, so the audience would be able to make comparisons directly.” As a result, when it came to the avatar animations, Spielberg scrutinized facial performance “to the nth degree,” says Cofer. “We could execute a shot to technical perfection, but if it wasn’t making an emotional connection to the character, it was a fail.”

A subtle design touch specified by Spielberg was that in extreme close-ups, the avatars’ faces would show a sort of chain-mail texture instead of pores. “Steven really wanted the CG sequences to feel like a live-action movie, with characters moving in and out of darkness and using lighting and framing to tell a story,” adds U.K.-based ILM visual effects supervisor Roger Guyett.

The DD capture stage was also used for stunts, including wire work to create a lively club sequence at a night spot called the Distracted Globe, where dancers twirl through the air. It’s one in a series of elaborate set-pieces that also include a road race through a morphing Manhattan landscape and an homage to Stanley Kubrick’s 1980 film “The Shining,” camped up with zombies.

The apocalyptic battle at the climax of the film lasts for roughly 30 minutes and was a production unto itself. “We started the third act with sketches Steven drew on his vacation and filmed with his iPhone, talking over it while he pushed in or panned across,” recalls Meadows. “It was very informative. He gave us about two hours of material.”

The motion capture for the battle scene was especially tricky due to characters of widely varying sizes interacting and appearing side by side. For the big battle, ILM drew on a new crowd system called Arcade. The software “makes heavy use of motion-capture vignettes,” Cofer says, “allowing them to populate a mo-cap database of unique characters that were highly directable.”

When all was said and done, Meadows notes that Spielberg used the virtual camera for more than 6,500 shots. “That’s the way Steven shoots,” he says. “He likes long, continuous shots. So he would shoot, then editorial would cut it up as needed, but you still have to do all the work and prepare those shots.”

Finally, stitching reality and Oasis together “took a real design sensibility,” explains Andrew Popplestone, creative director of Territory, whose credits include “Blade Runner 2049” and “Ghost in the Shell.” “Initially we worked very closely with production designer Adam Stockhausen from a brief that asked, how can we intrinsically knit the real world and virtual world?”

The answer, says Popplestone, was a graphic language. “What we wound up with was a graphical interface using the HUDs. It was a subtle thing, and important to make it seamless. We were the glue between those two worlds, as well as between the Digital Domain and ILM worlds.”