With thousands of shots and multiple iterations, compositing becomes a time-consuming endeavor unavailable for a television series. The Holy Grail of visual effects, a necessity for The Mandalorian, was made available with real-time, in-camera compositing. asc 
The solution was what might be described as the heir to rear projection — a dynamic, real-time, photo-real background played back on a massive LED video wall and ceiling, which not only provided the pixel-accurate representation of exotic background content, but was also rendered with correct camera positional data.
Notice where the led display meets the floor. enlarge
A behind the scenes look at the groundbreaking virtual production technology used on The Mandalorian.
Over 50 percent of The Mandalorian Season 1 was filmed using this ground-breaking new methodology, eliminating the need for location shoots entirely. Instead, actors in The Mandalorian performed in an immersive and massive 20’ high by 270-degree semicircular LED video wall and ceiling with a 75’-diameter performance space, where the practical set pieces were combined with digital extensions on the screens.
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Digital 3D environments created by ILM played back interactively on the LED walls, edited in real-time during the shoot, which allowed for pixel-accurate tracking and perspective-correct 3D imagery rendered at high resolution via systems powered by NVIDIA GPUs.
The environments were lit and rendered from the perspective of the camera to provide parallax in real-time, as if the camera were really capturing the physical environment with accurate interactive light on the actors and practical sets, giving showrunner Jon Favreau, executive producer and director Dave Filoni, visual effects supervisor Richard Bluff, and cinematographers Greig Fraser and Barry Baz Idoine, and the episodic directors the ability to make concrete creative choices for visual effects-driven work during photography and achieve real-time in-camera composites on set.
The technology and workflow required to make in-camera compositing and effects practical for on-set use combined the ingenuity of partners such as Golem Creations, Fuse, Lux Machina, Profile Studios, and ARRI together with ILM’s StageCraft virtual production filmmaking platform and ultimately the real-time interactivity of the Unreal Engine platform.