Roma's 'invisible effects' are a sight to behold

A foreign language, black-and-white film is probably not the first thing that springs to mind when it comes to visual effects. But Alfonso Cuaron's Oscar-winning Roma is filled with them, from digital set extensions and environments to CG animals and human performances.

To help us lock onto those incredibly well-hidden effects -- there's a reason they're called "invisible" -- one of Roma's VFX supervisors, Aaron Weintraub, took us through how his team at visual effects company Mr. X augmented several scenes.

Mr. X also released a handy YouTube video breaking down those scenes, which you can watch here.

"We replaced the entire façade and marquee of the cinema," Weintraub said via email. "Special attention was paid to the quality and texture of the stucco, and the painted quality of the signage."

"The original photography used multiple LED panels on the stage that projected the interactive light from the film onto the audience, so that their lighting would react with the changes in the light bouncing off the film screen," Weintraub said.

"Mr. X replaced the entire stage with a full-sized screen, added CG curtains that closed at the end of the film that warbled the image as it projected over them, and added atmosphere to illuminate the projection beam in the air and bounce light back into the environment. Special care was taken to preserve all the cigarette smoke and atmosphere from the original photography at it floated over top of the screen and through the beam."

"The backgrounds in these shots were completely replaced with street extensions, CG buildings, CG cars and trams, additional pedestrians, trolley tracks and wires, and all manner of period set dressing, TV antennas, water heaters, pipes, etc," Weintraub said.

"This was shot at the actual location represented in the film, but over the years, the hospital building had undergone a complete facelift and now required restoration to its 1970's glory," Weintraub said. "Mr. X replaced the building based on reference photographs of the original location and extended additional architecture into the deep background."

"The original photography had some great stuffed dog sculptures.  They helped establish the tone of the set and definitely set the scenes up for some of the best comedic moments in the film," Weintraub said. "Once photographed, however, Alfonso felt they were lacking some realism and that they didn't feel like actual dead dogs, so we replaced and augmented them with real dog elements."

"Mr. X added a burning falling CG tree, embers, additional ground fires and burning trees, cleaned up practical propane flame bars, and added fires wherever the kids were pouring water," Weintraub said.

"Not wanting to spend time to train an actual lizard to run and stop on cue, the plate was photographed with an actual lizard in the end position, waiting to be scooped up by the approaching hand," Weintraub said.

"Up until that point, the lizard was completely CG, modeled after the one in the shot and using additional reference photography to create the asset. The horned lizard was rigged and hand-animated to arrive into the position matching the original one, which was painted out of the plate and replaced to create a seamless pick-up event. It was integrated with lighting and shadows rolling over the rocky terrain to perfectly match the scene."

"One of the biggest shots in the film, the practical first-storey portion of the set was completely constructed from scratch on an empty lot," Weintraub said. "Concrete was poured and streetcar tracks were laid in so that they could bring in a practical trolley car, though because a historically accurate streetcar wasn't available, they painted a modern streetcar completely blue and ran that through the shot so that the actors and drivers had something physical to block their action.

"Mr. X digitally removed it and replaced it with a digital replica created using old photographs as reference. There was a bluescreen at the back of the set which allowed us to retain some of the foreground action without having to completely rotoscope the shot, but for anything that extended higher than the screen, roto was the only option. The street was digitally extended and populated with all manner of traffic, lamps, buildings, flashing signs, billboards, storefronts -- basically anything that filled up the frame and brought it to life in the way that Alfonso remembered it. The wet foreground concrete also had to be completely replaced, so that the puddles reflected all the digital additions to the architecture and traffic."