The Moving Camera
The persistence of vision or the illusion of continuous motion is frame-by-frame animation that is created with individual images which are then displayed in quick succession to create the illusion.
Keyframes help identify the major changes in a scene and are used as guides for creating the in-between frames that complete the look of the transitions placed between them. Classical frame-by-frame animation for film was extremely labor-intensive and involved creating drawings on compatible paper or semi-transparent vellum, back in the 1930s/40s.
Cel animation significantly reduced the labor required to layer foreground, middle-ground, and background elements onto sheets of celluloid film. Later the direct-to-film or camera-less technique was pioneered to create images/filmstrips with chemical compounds or similar processes such as burning, rubbing, stop-motion, etc.
Today, natural media tools on digital platforms give motion designers a much-needed sense of freedom. Interpolation software has the ability to calculate intermediate data between the keyframes placed to make linear or non-linear motions.
Spatial interpolation or path animation includes animating the position of an object through orientation or scale, while visual interpolation involves animating color, opacity, geometry, and the like. Temporal interpolation explains how the elements are chosen to move over time.
The temporal property of velocity is controlled by altering the distance between keyframes. Advanced techniques used in animation such as parenting and nesting allow the designer to connect and save specific types of motion and make changes to them on their own. Traditional camera motions are typically used in most cinematography as well as motion graphics applications.