The real process
Some actors talk or write about motion capture and 3D animation as ‘painting’ in the image. Painting? Really? That would make sense if you took a time machine back 100 years before computers and tried to explain it I suppose. But these days it makes as much sense as saying Michelangelo ‘doodled’ the David sculpture.
Short form: The performance of the actor is recorded and applied in some form to a Computer Graphic (CG) animated character.
Much much more can be read here.