Short answers, pulled from the story.
StageCraft is visual effects technology designed by Industrial Light & Magic. It uses large LED screens to surround live-action actors with high-definition video walls displaying computer-generated imagery backdrops.
Cinematographer Greig Fraser faced limitations with traditional green screens while shooting Rogue One in 2016. This frustration sparked an idea that led Richard Bluff and Rob Bredow from Industrial Light & Magic to begin developing the concept.
A second permanent volume opened at Manhattan Beach Studios in Los Angeles in March 2021. Another location began operations at Pinewood Studios in London by February 2021, and a fourth volume was announced for Vancouver in November 2021.
Unreal Engine handles the real-time three-dimensional rendering of environments within StageCraft facilities. ILM also introduced specialized software called Helios during the upgrade to StageCraft 2.0 specifically for this hardware.
The Midnight Sky and The Batman both employed the technology upon release in 2020 and 2022 respectively. Thor: Love and Thunder and Black Adam integrated virtual production elements into their narratives following these initial releases.