The in-camera special effect, used in countless films, as old as cinema itself.
First the what, then the how. Fandor explains rear projection, and the history of its use in Hollywood cinema:
After seeking advice from professor of cinematography Charles Haine, Ted from Indy Mogul recreates a more traditional style rear projection shoot:
Try It Yourself
Give filmmakersworld‘s creative TV-backdrop shot a try (via No Film School):
In their exercise, Film Riot utilise a high contrast, short-throw projector:
The example above makes mention of the immersive, wrap-around LCD panel environment known as The Volume, pioneered in productions such as the Disney / Star Wars series, The Mandalorian – more on that here: