In the traditional animation process, animators will begin by drawing sequences of animation on sheets of transparent paper perforated to fit the peg bars in their desks, often using color pencils, one picture or “frame” at a time. A peg bar is an animation tool that is used in traditional (cel) animation to keep the drawings in place. The pins in the peg bar match the holes in the paper. It is attached to the animation desk or light table depending on which is being used. A key animator or lead animator will draw the key drawings in a scene, using the character layouts as a guide. The key animator draws enough of the frames to get across the major points of the action; in a sequence of a character jumping across a gap, the key animator may draw a frame of the character as he is about to leap, two or more frames as the character is flying through the air, and the frame for the character landing on the other side of the gap.
Timing is important for the animators drawing these frames; each frame must match exactly what is going on in the soundtrack at the moment the frame will appear, or else the discrepancy between sound and visual will be distracting to the audience. For example, in high-budget productions, extensive effort is given in making sure a speaking character’s mouth matches in shape the sound that character’s actor is producing as he or she speaks.
While working on a scene, a key animator will usually prepare a pencil test of the scene. A pencil test is a preliminary version of the final animated scene; the pencil drawings are quickly photographed or scanned and synced with the necessary soundtracks. This allows the animation to be reviewed and improved upon before passing the work on to his assistant animators, who will go add details and some of the missing frames in the scene. The work of the assistant animators is reviewed, pencil-tested, and corrected until the lead animator is ready to meet with the director and have his scene sweat boxed or reviewed by the director, producer, and other key creative team members. Similar to the story boarding stage, an animator may be required to re-do a scene many times before the director will approve it.
In high-budget animated productions, often each major character will have an animator or group of animators solely dedicated to drawing that character. The group will be made up of one supervising animator, a small group of key animators, and a larger group of assistant animators. For scenes where two characters interact, the key animators for both characters will decide which character is “leading” the scene, and that character will be drawn first. The second character will be animated to react to and support the actions of the “leading” character.
Once the key animation is approved, the lead animator forwards the scene on to the clean-up department, made up of the clean-up animators and the inbetweeners. The clean-up animators take the lead and assistant animators’ drawings and trace them onto a new sheet of paper, taking care in including all of the details present on the original model sheets, so that it appears that one person animated the entire film. The inbetweeners will draw in whatever frames are still missing in between the other animators’ drawings. This procedure is called tweening. The resulting drawings are again pencil-tested and sweat boxed until they meet approval.
At each stage during pencil animation, approved artwork is spliced into the Leica reel.
This process is the same for both character animation and special effects animation, which on most high-budget productions are done in separate departments. Effects animators animate anything that moves and is not a character, including props, vehicles, machinery and phenomena such as fire, rain, and explosions. Sometimes, instead of drawings, a number of special processes are used to produce special effects in animated films; rain, for example, has been created in Disney animated films since the late-1930s by filming slow footage of water in front of a black background, with the resulting film superimposed over the animation.