Rotoscoping is specifically tracing over a sequence of images - usually video or film frames - to create a sequence of drawings that can be used in an animation workflow.
https://en.wikipedia.org/wiki/Rotoscoping
Spaceballs’ State Of The Art and 9 Fingers are a couple of Amiga demoscene productions that relied on rotoscoping.
Right, I suppose you would call what Norman Rockwell was doing was tracing?
I still see them as largely related? That not considered the case?