"Using the LED walls and #UnrealEngine for real-time in-camera visual effects enabled the #Westworld team to capture physically accurate lighting from the environment coming through the glass, with accurate reflections ... (and) with the right parallax"...
https://www.unrealengine.com/en-US/spotlights/hbo-s-westworld-turns-to-unreal-engine-for-in-camera-visual-effects