Set Extension

Set extension is the VFX technique of extending a physical set built for camera with digital architecture, environment or detail beyond what was constructed. The technique is essential in productions where building the entire required environment is impractical or impossible: extending a real building's facade to make it look larger, replacing a flat wall behind an actor with a CG landscape, adding distant city skylines to a foreground real set. Modern set extensions use a combination of camera tracking (to determine where the camera was in 3D space), digital matte painting (traditional painted-on-glass replaced by Photoshop/Mari/Substance work), 3D modeling (for elements that require parallax with camera movement), atmospheric and lighting matching (the digital extension must match the on-set lighting conditions), and compositing (integrating the digital element with the live plate through edge work, color matching, grain matching). The shift to virtual production stages with LED walls (used heavily on The Mandalorian, Mandalorian-style backings) is changing the landscape: set extensions can now happen in real-time on the LED wall during photography rather than in post. However, traditional post-based set extension remains the workflow for most productions due to cost and flexibility. Reference: VES Handbook of Visual Effects, chapter on environment work.