Sandra Bullock spent six months in physical training to prepare for shooting while reviewing the script with Cuarón in meticulous detail. Cuarón said, "More than anything else, we were just talking about the thematic element of the film, the possibility of rebirth after adversity." They worked out how she would perform each scene, and her notes were included the pre-vis animation and programming for the robots. Cuarón and Bullock zeroed in on one crucial aspect of the performance: Stone's breath, "and how that breath was going to dictate her emotions," he said. "That breath that is connected with stress in some instances, but also the breath that is dictated by lack of oxygen." Their conversations covered every detail of the script and Bullock's character. "She was involved so closely in every single decision throughout the whole thing," Cuarón said. "And it was a good thing, because once we started prepping for the shoot, it was almost more like a dance routine, where it was one-two-three left, left, four-five-six then on the right. She was amazing about the blocking and the rehearsal of that. So when we were shooting, everything was just about truthfulness and emotion."
James Cameron, best friend of Cuarón and a huge fan of the film, said Bullock's work is more impressive than the technology that supported it. "She's the one that had to take on this unbelievable challenge to perform it. (It was) probably no less demanding than a Cirque du Soleil performer, from what I can see." And of the result, he said, "There's an art to that, to creating moments that seem spontaneous but are very highly rehearsed and choreographed. Not too many people can do it. ... I think it's really important for people in Hollywood to understand what was accomplished here."
Though the film itself is scientifically accurate in depicting no sound in space, sound effects were added to the film's trailers to make them appear more exciting.
Alfonso Cuarón, cinematographer
Emmanuel Lubezki, and visual effects supervisor
Tim Webber decided that they couldn't make
Gravity as they wanted to by simply using traditional methods. So for the spacewalk scenes, says Webber, "We decided to shoot (the actors') faces and create everything else digitally. Which was quite a difficult decision." To do that, Lubezki reasoned, he would need to light the faces to match the all-digital environment they'd be put into. Whether the characters were floating gently, changing direction or tumbling in space, the facial light would have to be a perfect match for the Earth, sun and stars in the background. "That can break easily," explains Lubezki, "if the light is not moving at the speed that it has to move, if the position of the light is not right, if the contrast or density on the faces is wrong, et cetera." Lubezki suggested folding an LED screen into a box, putting the actor inside, and using the light from the screen to light the actor. That way, instead of moving either Bullock or Clooney in the middle of static lights, the projected image could move while they stayed still and safe. This "light box" became the key to the spacewalk scenes. But it was only a nine-foot cube, just big enough for one actor, not an actor and a camera crew.
Gravity had languished in development hell for four years, because the film's ambition - in terms of the cinematography, visual effects, and realistic "story atmosphere" of outer space - proved to be too challenging and Cuarón had to wait for the technology to be far more advanced and progressed to meet his vision; that was finally realized in 2009 with
James Cameron's
Avatar.
A chance meeting between their siblings lead to Astronaut Cady Coleman placing a phone call from the International Space Station to Sandra Bullock to speak with her about life in space.
Natalie Portman was the top choice for the lead role after
Angelina Jolie twice refused it. Portman turned down the role shortly before she announced her pregnancy.
Robert Downey Jr. was cast but dropped out due to scheduling conflicts.
Alfonso and 'Jonas Cuarón' developed the film's script at Universal Pictures, where Alfonso had co-written and directed
Children of Men for Universal in 2006. Universal was hoping to attach
Angelina Jolie to the project, but decided the picture would be too expensive, and put
Gravity into turnaround. Warners picked it up, and Cuarón cast Bullock and
Robert Downey Jr. in late 2010 for the leads. Downey subsequently dropped out and was replaced by Clooney at the end of the year.
Angelina Jolie was originally cast but dropped out later.
Rachel Weisz,
Naomi Watts,
Natalie Portman,
Marion Cotillard,
Abbie Cornish,
Carey Mulligan,
Sienna Miller,
Scarlett Johansson,
Blake Lively,
Rebecca Hall and
Olivia Wilde were all subsequently tested or approached for the lead role. Finally,
Sandra Bullock was cast.
This is the first film project for producer
David Heyman since the Harry Potter film series came concluded with
Harry Potter and the Deathly Hallows: Part 2 in 2011. This is also the first collaboration between Heyman and
Alfonso Cuarón since
Harry Potter and the Prisoner of Azkaban.