No, it isn't entirely real: Director Alfonso Cuaron takes a subtle tack in his black-and-white look at life in 1970s Mexico City than he did in 2013's 'Gravity.' But the digital work, all in the service of naturalism, is just as magical.

On the face of it, Roma hardly looks like a typical visual effects movie. In scrupulously re-creating the middle-class family life he knew growing up in Mexico City during the early 1970s, writer-director Alfonso Cuaron aims for a low-key realism that finds drama in even the most routine moments of ordinary life. But, in fact, the majority of the $15 million film, which began streaming Dec. 14 on Netflix, involves some degree of visual effects work, according to VFX supervisor Dave Griffiths of the film's lead VFX house, MPC. Of course, Cuaron knows all about cutting-edge VFX techniques — his 2013 film Gravity, for which he won a best directing Oscar, was hailed for its effects. But while Gravity's VFX couldn't be ignored — how else do you set two A-list stars adrift in space? — in Roma, the effects work is virtually invisible.

Take the bravura extended tracking shot when the family's housekeeper, Cleo (Yalitza Aparicio), watches the family's kids at the beach as they charge into the water, then rushes into the pounding waves when two of the smaller children appear to be struggling. Cuaron presents the sequence as if it is one uninterrupted shot. But to achieve that appearance, several shots had to be stitched together and the whole setting digitally manipulated. "We ended up extending the shot by putting in a new middle section from other takes," explains Griffiths, "enhancing the drama and danger."

In effect, Cuaron, who served as his own cinematographer, was following in the footsteps of his frequent cinematographer, Emmanuel "Chivo" Lubezki, who won an Oscar for shooting 2014's Birdman as if the entire movie were filmed in one continuous take. In that case, Lubezki was able to use doorways and backstage passages to disguise where some of the shots were stitched together. The challenge in Roma's beach scene was that all the shots of sea, sky and sand had to be flawlessly matched to make the manufactured tracking shot convincing.

Several different takes of Cleo rescuing the children were involved, and some takes of the children were repositioned. Certain views of the sky also were replaced. "The time of day was different, so we had to match up and grade the actual water and reflection — it was a tricky shot," acknowledges Griffiths. Cuaron also requested that the height of the water be adjusted so that it would look deeper. "So there was a lot of work to do in compositing in that section," he adds, "and then at the end of the shot, we cut back to the original take."

Throughout the film, other digital tweaks were made. The neighborhood surrounding the family's home required a lot of bluescreen work to eliminate any modern sights and to extend the street on which the home sits into the distance. But the most challenging shot, says Griffiths, was actually one that looks the simplest: the opening sequence starts with water sloshing across a tile floor. As the shot proceeds, multiple takes were combined as the camera moves along the surface to follow Cleo at work. Notes Griffiths, "That was quite an intense shot."

This story first appeared in the Dec. 18 issue of The Hollywood Reporter magazine. To receive the magazine, click here to subscribe.