Screen-relative speed
Describing the speed of an object by the share of the frame it crosses in a given time, rather than with an adjective.
Why it matters in production
Video generators slow fast objects down to keep the image coherent. “The plane takes off” gives a plane that floats; “it crosses half the frame in two seconds and exits through the top edge” gives a real take-off. We measure on the failed shot, rewrite in fractions of the frame, regenerate.
Other names
frame-relative motion
