Wow. Released in Scotland next week, Alfonso Cuaron's science fiction drama is being heralded as a game changer for space movies and 3D.
Speaking at a London Film Festival masterclass last month, the Mexican director of Harry Potter And The Prisoner Of Azkaban, and Tim Webber of Framestore, the film's visual effects supervisor and the man who made the magic happen, were keen not to give away too many secrets. After all, everyone wants to go see the wizard, but who really wants to know what is behind the curtain?
"People should experience the film first and then eventually we will be very happy to spill all the beans for people who are interested in how things were done," said Cuaron. "The most important thing for us is that all of that stuff, all this technology, are nothing but tools to achieve a cinematic experience, a cinematic moment."
The two did, however, explore some of the previously final frontiers that had to be crossed to make the movie. Starring Sandra Bullock and George Clooney, Gravity is the tale of a team of astronauts working 370 miles above earth. The scientists and techies have set off on what is meant to be a routine mission. The only trouble is, no one has told space that.
Cuaron and Webber first worked together when the latter created the digital baby in Children Of Men. When Cuaron brought Webber the idea for Gravity it was thought the film would take a year to make. In the end, it took four and a half.
Webber, who handily has a degree in physics, thought Cuaron's vision could be realised, but he knew it would not be easy.
"I kind of knew it would be a challenging movie, but I don't suppose I knew quite how challenging."
Cuaron was also warned by fellow directors that interesting times might lie ahead. David Fincher (Alien 3) and James Cameron (Aliens, Avatar), both given special thanks in the credits, were among those Cuaron took soundings from when he had early scenes to show.
"Fincher said, 'Wow, this is great but you have to wait seven years for the technology to catch up'," recalled Cuaron. Cameron reckoned the technology was out there, but Cuaron had to invent the set of tools that could use it. He also thought the film could be made for £250 million (the budget is reported to be a quarter of that).
The first problem was creating the zero gravity of space. Webber and Cuaron tried a reduced gravity aircraft, dubbed a "vomit comet", which is mainly used for training astronauts. "Best piece of research ever," said Cuaron. "I was embarrassed to show the footage because it didn't look like I was working," said Webber.
A vomit comet was no use, however, for the kind of wide angle shots required in many scenes, and the extended shots that are Cuaron's trademark. Another option was to do the whole thing with computers, but Cuaron's response was "no way". Wires were not an option because they would be seen, and the astronauts would become tangled up as they rotated.
Once they eventually arrived at a solution - all will be revealed in a "making of" segment in the eventual DVD/Blu Ray, they promise - the next problem was lighting. Emmanuel "Chivo" Lubezki, the director of photography, had to find a way to recreate the way light behaves in space, and in particular the way it bounces off the earth. His eureka moment came at a Peter Gabriel concert when he watched the way the LED lights operated.
As the extremely long credits list testifies, it took a lot in the way of time, effort, bodies and talent to bring the story to the screen. At every stage, says Cuaron, the aim was to get as close a match as possible to actually shooting in space (they considered that for a while, too, until the estimate came in).
"At our first meeting I remember saying I want at the end of this film to receive a call from Nasa suing us for hiding cameras in their (ships)," says Cuaron, laughing. To keep everyone on track, he papered the production office with Nasa-produced, high resolution shots of space, continually asking, "Is it going to look like this, Tim?"
The shoot itself turned out to be a complex affair. When something went wrong it was the equivalent of that moment at Christmas when the lights on the tree stop working because of one defective bulb. In Gravity's case it was a question of hunt the cable. "The set was just rows and rows of computers and cables and geeks running around," said Cuaron.
All of the high tech, however, would be have been for nothing without the human element, and Bullock in particular.
"It was tough on her," said Cuaron. "I've never seen a film in which the collaboration between the visual effects supervisor, director of photography and actor is so close. Sandra would talk as much with me as with Tim and Chivo. On the one hand you had Chivo and Tim trying to make things as easy for Sandra, and Sandra was always trying to make things easier for them."
Webber recalled: "She was incredibly willing and incredibly able. Unbelievable."
Next week, seeing becomes believing.
Gravity opens in cinemas on November 8