Principles Of Animation

Animation is a graphic representation of drawings to show movement within those drawings.  A series of drawings are linked together and usually photographed by a camera.  The drawings have been slightly changed between individualized frames so when they are played back in rapid succession (24 frames per second) there appears to be seamless movement within the drawings.

The First Animated Feature film

Pioneers of animation include Winsor McCay of the United States and Emile Cohl and Georges Melies of France.  Some consider McCay’s Sinking of the Lusitania from 1918 as the first animated feature film.

Early animations, which started appearing before 1910, consisted of simple drawings photographed one at a time.  It was extremely labor intensive as there were literally hundreds of drawings per minute of film.  The development of celluloid around 1913 quickly made animation easier to manage.  Instead of numerous drawings, the animator now could make a complex background and/or foreground and sandwich moving characters in between several other pieces of celluloid, which is transparent except for where drawings are painted on it.  This made it unnecessary to repeatedly draw the background as it remained static and only the characters moved.  It also created an illusion of depth, especially if foreground elements were placed in the frames.

The 12 Principles of Animation

Many of the principles of traditional animation were developed in the 1930’s at the Walt Disney studios. These principles were developed to make animation, especially character animation, more realistic and entertaining. These principles can and should be applied to 3D computer animation.

The 12 basic principles of animation is a set of principles of animation introduced by the Disney animators Ollie Johnston and Frank Thomas in their 1981 book The Illusion of Life: Disney Animation. Johnston and Thomas in turn based their book on the work of the leading Disney animators from the 1930s onwards, and their effort to produce more realistic animations. The main purpose of the principles was to produce an illusion of characters adhering to the basic laws of physics, but they also dealt with more abstract issues, such as emotional timing and character appeal.

1.Squash and stretch

(Defining the rigidity and mass of an object by distorting its shape during an action)

The most important principle is “squash and stretch”,the purpose of which is to give a sense of weight and flexibility to drawn objects. It can be applied to simple objects, like a bouncing ball, or more complex constructions, like the musculature of a human face.

When real objects move only totally rigid ones, e.g., a chair, remain rigid in motion. Living creatures always deform in shape in some manner. For example, if you bend your arm, your bicep muscles contract and bulge out. They then lengthen and disappear when your arm straightens out. The squashed position shows the form flattened out and the stretched position shows the form extended. An important rule is that the volume of the object should remain constant at rest, squashed, or stretched. If this rule is not obeyed, then the object appears to shrink when squashed and to grow when stretched.

A classic example is a bouncing ball, that squashes when it hits the ground and stretches just before and after. The stretching, while not realistic, makes the ball appear to be moving faster right before and after it hits the ground.

When an object squashes or stretches, it appears to be made of a pliable material, if it doesn’t then it appears rigid. Objects that are partially pliable and partially rigid should have only the pliable parts deform.

Taken to an extreme point, a figure stretched or squashed to an exaggerated degree can have a comical effect. In realistic animation, however, the most important aspect of this principle is the fact that an object’s volume does not change when squashed or stretched. If the length of a ball is stretched vertically, its width (in three dimensions, also its depth) needs to contract correspondingly horizontally.

2. Anticipation

(The preparation for an action)

Anticipation can be the anatomical preparation for the action, e.g., retracting a foot before kicking a ball. It can also be a device to attract the viewer’s attention to the proper screen area and to prepare them for the action, e.g., raising the arms and staring at something before picking it up, or staring off-screen at something and then reacting to it before the action moves on-screen. An example of this is the opening scene of Luxo, jr.. The father is looking off-screen and then reacts to something.

An action occurs in three parts:

1. the preparation for the action – this is anticipation
2. the action
3. the termination of the action

A properly timed anticipation can enable the viewer to better understand a rapid action, e.g., preparing to run and then dashing off-screen.

Anticipation can also create the perception of weight or mass, e.g., a heavy person might put their arms on a chair before they rise, whereas a smaller person might just stand up.

3.Staging

(presenting an idea so that it is unmistakably clear)

The purpose of staging is to direct the audience’s attention, and make it clear what is of greatest importance in a scene; what is happening, and what is about to happen.This can be done by various means, such as the placement of a character in the frame, the use of light and shadow, and the angle and position of the camera.The essence of this principle is keeping focus on what is relevant, and avoiding unnecessary detail.

In the early days at Disney all characters were black and white, with no gray. All action was shown in silhouette (to the side), because if a character moved its black arm in front of its black body it would disappear, so the action had to be against the white background. The Disney animators realized that even without this technological limitation action was more clearly visible in silhouette.

Even with modern color 3D graphics, silhouette actions are more clearly delineated and thus to be preferred. over frontal action. An example would be a character waking up and scratching its side, it is easier to understand what it is doing than if it scratched its stomach.

4. Timing

(Spacing actions to define the weight and size of objects and the personality of characters)

The speed of an action, i.e., timing, gives meaning to movement, both physical and emotional meaning. The animator must spend the appropriate amount of time on the anticipation of an action, on the action, and on the reaction to the action. If too much time is spent, then the viewer may lose attention, if too little, then the viewer may not notice or understand the action.On a purely physical level, correct timing makes objects appear to abide to the laws of physics; for instance, an object’s weight decides how it reacts to an impetus, like a push. Theatrical timing is of a less technical nature, and is developed mostly through experience. It can be pure comic timing, or it can be used to convey deep emotions. It can also be a device to communicate aspects of a character’s personality

Timing can also affect the perception of mass of an object. A heavier object takes a greater force and a longer time to accelerate and decelerate. For example, if a character picks up a heavy object, e.g., a bowlng ball, they should do it much slower than picking up a light object such as a basketball. Similarly, timing affects the perception of object size. A larger object moves more slowly than a smaller object and has greater inertia. These effects are done not by changing the poses, but by varying the spaces or time (number of frames) between poses.

Timing can also indicate an emotional state. Consider a scenario with a head looking first over the right shoulder and then over the left shoulder. By varying the number of inbetween frames the following meanings can be implied:

• No in-betweens – the character has been hit by a strong force and its head almost snappedd off
• One in-betweens – the character has been hit by something substantial, .e.g., frying pan
• Two in-betweens – the character has a nervous twitch
• Three in-betweens – the character is dodging a flying object
• Four in-betweens – the character is giving a crisp order
• Six in-betweens – the character sees something inviting
• Nine in-betweens – the character is thinking about something
• Ten in-betweens – the character is stretching a sore muscle

5.Slow in & Slow out

(The spacing of the in-between frames to achieve subtlety of timing and movement)

The movement of the human body, and most other objects, needs time to accelerate and slow down. For this reason, an animation looks more realistic if it has more frames near the beginning and end of a movement, and fewer in the middle. This principle goes for characters moving between two extreme poses, such as sitting down and standing up, but also for inanimate, moving objects.

This is usually achieved by using splines to control the path of an object. The various spline parameters can be adjusted to give the required effect. In 3D Studio this is controlled by the parameters Ease To and Ease From in the Key info window (from the Track info window). When these are zero, there is a constant velocity in either direction, i.e., to/from the keyframe. When Ease To is set to a higher value, the motion is faster as it leaves the previous keyframe and slows as it approaches the current keyframe. When Ease From is set to a higher value the motion is slower leaving the current keyframe and speeds up as it approaches the next keyframe. The tick mark spacing shows the velocity with closer tick marks indicating a slower rate and spaced out ones indicating a faster rate.

6.Follow through and overlapping action

(The termination of an action and establishing its relationship to the next action)

These closely related techniques help render movement more realistic, and give the impression that characters follow the laws of physics. “Follow through” means that separate parts of a body will continue moving after the character has stopped.”Overlapping action” is when a character changes direction, and parts of the body continue in the direction he was previously going.

An example is in throwing a ball – the hand continues to move after the ball is released. In the movement of a complex object different parts of the object move at different times and different rates. For example, in walking, the hip leads, followed by the leg and then the foot. As the lead part stops, the lagging parts continue in motion.

Here is a quote about overlapping from Walt Disney:

“It is not necessary for an animator to take a character to one point, complete that action completely, and then turn to the following action as if he had never given it a thought until after completing the first action. When a character knows what he is going to do he doesn’t have to stop before each individual action and think to do it. He has it planned in advance in his mind.”

7.Straight ahead action and pose to pose

(The two contrasting approaches to the creation of movement)

Straight Ahead Action in hand drawn animation is when the animator starts at the first drawing in a scene and then draws all of the subsequent frames until he reaches the end of the scene. This creates very spontaneous and zany looking animation and is used for wild, scrambling action.

Pose-to-Pose Action is when the animator carefully plans out the animation, draws a sequence of poses, i.e., the initial, some in-between, and the final poses and then draws all the in-between frames (or another artist or the computer draws the inbetween frames). This is used when the scene requires more thought and the poses and timing are important.

Computer animation removes the problems of proportion related to “straight ahead action” drawing; however, “pose to pose” is still used for computer animation, because of the advantages it brings in composition. The use of computers facilitates this method, as computers can fill in the missing sequences in between poses automatically. It is, however, still important to oversee this process, and apply the other principles discussed.

8.Appeal

(Creating a design or an action that the audience enjoys watching)

Appeal in a cartoon character corresponds to what would be called charisma in an actor. A character who is appealing is not necessarily sympathetic — villains or monsters can also be appealing — the important thing is that the viewer feels the character is real and interesting.

9.Exaggeration.

(Accentuating the essence of an idea via the design and the action.)

Exaggeration does not mean just distorting the actions or objects arbitrarily, but the animator must carefully choose which properties to exaggerate. If only one thing is exaggerated then it may stand out too much. If everything is exaggerated, then the entire scene may appear too unrealistic.

It is an effect especially useful for animation, as perfect imitation of reality can look static and dull in cartoons. The level of exaggeration depends on whether one seeks realism or a particular style, like a caricature or the style of an artist. The classical definition of exaggeration, employed by Disney, was to remain true to reality, just presenting it in a wilder, more extreme form. Other forms of exaggeration can involve the supernatural or surreal, alterations in the physical features of a character, or elements in the storyline itself. It is important to employ a certain level of restraint when using exaggeration; if a scene contains several elements, there should be a balance in how those elements are exaggerated in relation to each other, to avoid confusing or overawing the viewer.

10.Arcs

(The visual path of action for natural movement)

Most human and animal actions occur along an arched trajectory, and animation should reproduce these movements for greater realism. This can apply to a limb moving by rotating a joint, or a thrown object moving along a parabolic trajectory. The exception is mechanical movement, which typically moves in straight lines.

11.Secondary action.

(The action of an object resulting from another action)

This is an action that directly results from another action. It can be used to increase the complexity and interest in a scene. It should always be subordinate to and not compete with the primary action in the scene. An example might be the facial expression on a character.

Adding secondary actions to the main action gives a scene more life, and can help to support the main action. A person walking can simultaneously swing his arms or keep them in his pockets, he can speak or whistle, or he can express emotions through facial expressions. The important thing about secondary actions is that they emphasize, rather than take attention away from the main action. If the latter is the case, those actions are better left out. In the case of facial expressions, during a dramatic movement these will often go unnoticed. In these cases it is better to include them at the beginning and the end of the movement, rather than during.

12.Solid Drawing.

The principle of solid — or good — drawing, really means that the same principles apply to an animator as to an academic artist. The drawer has to understand the basics of anatomy, composition, weight, balance, light and shadow etc. For the classical animator, this involved taking art classes and doing sketches from life. One thing in particular that Johnston and Thomas warned against was creating “twins”: characters whose left and right sides mirrored each other, and looked lifeless. Modern-day computer animators in theory do not need to draw at all, yet their work can still benefit greatly from a basic understanding of these principles.