http://electronicdesign.com/article/embedded/prometheus-takes-flight-cuttingedge-vfx-technology-73934 skrev:

Only about half of Prometheus has digital effects. There also was a significant number of sets and exterior shots in a variety of locations from Iceland to Scotland to Jordan. Chroma key compositing can be used in some cases. “Green screen” is variation of chroma key compositing where an actor can be photographed in front of a green background that is then digially replaced in post production by another background. More often, the VFX support required a significant amount of rotoscaping to help replace the background.

Rotoscaping is a manually intensive process where an animator edits each frame to cut out what isn’t wanted. A spline outline for an adjacent frame is typically used with each frame because the frames tend to be similar, requiring minor adjustments. The process is the same for 3D, but there are twice as many frames to consider and 3D placement is an issue. Similar editing challenges arise in blending dusty environments.

Scott didn’t use motion capture in Prometheus, though one scene took a low-tech aproach as actors carried torches in a dark tunnel. An alien character was equipped with regular red LED markers on its joints. The actors then were able to interact with the alien, and the hand animation was added in post-production based on the LEDs. Other approaches using infrared LEDs or other motion capture sensors would have been more expensive and time consuming, while the red LEDs still got the job done.

Some objects were real but augmented, like the RT01 Transport (Fig. 4). It’s almost always easier to film a prop like this when the actors will interact with it. Of course, special effects sometimes are required, like when David 8 puts on a 3D light show after a discovery on an alien vessel (Fig. 5).

The Sounds Of Sci-Fi
Prometheus was recorded using Dolby Surround 7.1, the industry-standard eight-channel sound system. It already provides 3D audio that naturally complements 3D video. Doug Hemphill and Ron Bartlett were part of the post-production team responsible for combining the film’s dialog, music and sound effects.

Hemphill and Bartlett worked closely with Ridley Scott to deliver a “gritty track with highly styled acoustic environments” in this sci-fi horror film. Bartlett recorded Sanskrit syllables that were modified and used with controls, buttons, and background sounds to provide ancient language audio motifs.

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The filmmakers took advantage of 3D sound effects, which are the norm in the movie industry today, during the film’s production as well. For example, audio can be matched with the video to highlight visual artifacts that are in the foreground.

The audio effort was almost as massive as the video work. A 100-person choir was recorded at the Abbey Road studio. This recording was added at epic moments within the film. At one point, the producers were generating five different audio mixes of the entire film in one week.