Complex sentence: In motion capture sessions, movements of one or more actors are sampled many times per second, early techniques used images from multiple cameras and calculate 3D positions, motion capture often records only the movements of the actor, not his or her visual appearance.
Split into simpler sentences: In motion capture sessions, movements of one or more actors are sampled many times per second. Whereas early techniques used images from multiple cameras to calculate 3D positions, often the purpose of motion capture is to record only the movements of the actor, not his or her visual appearance.