One of the main job I dreamed about during my teens was 2D animator: giving life to drawing in Disney movies, cartoons and animes. I was entranced by the movement of drawing, by the illusion of life it created.
For better or for worse, I was never particularly visual, and I didn't like drawing; -- so I eventually abandoned this dream for more conceptual endeavors (leading to epistemology and this blog!)
But in all these years, I never stopped thinking from time to time about The 12 Principles of Animation. These are rules and methods developed by Disney animators that codified animation and turned it from jittery gag cartoons to an art form. These principles are still taught to every new animator, applied in 3D animation, and generally provide the basis of modern innovations. They are the soil on which the art of animation grows.
I didn't know at the time, but what was so fascinating to me in the 12 principles was that they actually capture and share some of the most important abstractions for thinking about animation. They encode what to focus on and what to neglect, as well as constraints that made the animator's life easier (even thought they were not strictly speaking necessary). From the infinite of all possible sequences of drawing, these principles highlight particular features that every animator must keep in mind, for they impact the feeling of life itself.
So in honor of my past dream, let's go through the kind of abstraction that these principles provide!
(For copyright reasons, I cannot share the great pictures that illustrate and explain these principles in the book I'm reading. But I can recommend the book! It's The Illusion of Life, a great book discussing the history of Disney animation by two of the Nine Old Men)
Let's start by going through the 12 principles quickly. Then I'm going to deconstruct what they offer the animator, and we'll see the complex underlying structure of the knowledge, abstractions, and design choices they capture.
Squash and Stretch: living things don't move perfectly rigidly; instead they compress (squash) and extend (stretch). So animation that feels alive should also squash and stretch.
For example, before jumping characters squash themselves, and after they push they extend themselves in the direction of the jump.
Anticipation: what is going to happen should be made obvious so the audience can understand it (and potentially be surprised by some subversion of the expectation).
For example, the character might look at his pocket and bring his arm back before going to get a sandwich out of it.
Staging: As quoted from the book “it is the presentation of an idea so that it is completely and unmistakably clear. An action is staged so that it is understood, a personality so that it is recognizable, a mood so that it will affect the audience.”
For example, the camera angle is not a panorama if the core of the scene is the facial expression of the character.
Straight Ahead Action and Pose to Pose: there are two methods for creating an animation:
Straight Ahead Action starts for the first drawing, and then draws all others in order, giving a wild and organic feel;
Pose to Pose fixes and refine the key poses, then draw the in-betweens, giving structure and flowing movement.
Follow Through and Overlapping Action: when a character finishes a movement (say a big jump), instead of having them stand still, use the various speed of different parts of body, flesh, appendages, clothes, to maintain some form of movement. And also, the character can overreach the final pose, and then go back.
Slow In and Slow Out: to produce a feeling of zipping from one key pose to another, crowd the in-betweens around the key poses, giving much more time frames to going into and out of them.
Arcs: Living beings move in arcs, not straight-lines. So draw in-between in arcs.
Secondary Action: Use smaller complimentary actions to reinforce a movement, a mood, a personality.
For example, add a slouched body expression to a tearful face
Timing: How many drawing there are in an action, and how they are spaced, greatly influence our reading of what the action is about, and the personality it reveals.
A few drawings makes the action a snap, whereas a lot of drawings makes the action leisurely, maybe even searching and unsure.
Exaggeration: Animation can be more real than reality by getting to the core of a movement or an emotion, and amping it up.
Solid Drawing: Fundamentals of shape, volume, and line matter much more than tricks and sophisticated details.
Appeal: Characters should have some charm. To quote from the book again “To us, it means anything that a person likes to see, a quality of charm, pleasing design, simplicity, communication, and magnetism.”
Already you can see that the principles vary wildly: some are observations about living beings, other are constraints, still others are methods or techniques to solve specific problems or produce particular effects.
What I'm interested in is the general system of thinking that the 12 principles teach us. If some animator internalizes them, how are they going to make them better able to find the right animation for the right time?
First, like any practical advice, the principles build on a foundation of regularities in the world. That is, they build on some patterns in the system of interest that are powerful and reliable enough to be exploited.
For an animator, what matters is primarily the regularities on how movement is perceived by humans, which constitute the audience. And particularly, movement of living things, such as humans and animals.
Most principles in the 12 offer some insight on what matters in movement, often mixed with techniques to exploit that regularity and design choices on what is the goal of animation.
Squash and stretch highlights that living beings are made of flesh, and that this flesh doesn't move rigidly, but compresses and extends. It also makes the stronger observation that this is one of the key ways people recognize the movement of living beings.
Anticipation points out that almost all movements in living beings have some kind of preparation/startup, but more importantly that the clarity of such preparation strongly impacts how readable and understandable the action is for the audience.
Staging discusses what in the way a scene is composed impacts its readability, from the camera angle to the background and the silhouettes.
Follow Through and Overlapping Action leverage the observation that most parts of the body (flesh and skeleton, clothes, appendages) don't move at the same speed, and so don't finish their movement at exactly the same time. It also uses the idea of some inertia in movement, which makes living being overshoot and then correct back to their intended final position.
Arcs clearly is all about a regularity: that living beings move in arcs and not straight lines.
Secondary Action reminds the animator that multiple independent parts of a movement often reinforce the same impression, mood, personality.
Timing points out how the time taken by an action affects the audience interpretation of what the action means, and even of the personality of the character.
Exaggeration makes clear that the regularities in the other principles are in some sense sufficient to a sense of life and living movement -- as long as they are respected, the movement can be wildly intensified and exaggerated, and still work.
Solid Drawing lastly points out how the feeling of shape and volume, of asymmetry in perspective, matters much more for the audience perception of reality and substance than any trick or little detail.
So we get a model of what creates the illusion of life, what makes the audience feels like the characters are real and believable in their movements.
Next, I want to disentangle the design choices made by Disney animators from the principle themselves. You see, these principles were forged in order to accomplish concrete goals that Disney studios had, and so they are making a few design choices on what the goal and needs of animations are. It's good to make them explicit so we can keep in mind which ones we want to keep and which one don't apply to us.
I mostly see three design decisions embedded in the 12 principles:
Animation should create an illusion of life by making characters feel like living breathing beings
Every scene and action should be made as clear as possible.
This is made explicit in staging, and in secondary action.
Every character should have appeal, that is not be ugly or uninteresting
This is made explicit in appeal
Clearly, 1 is pretty much applicable to all animation, 2 is a more limiting constraint (but it also lead to rules and approaches which can easily be extended to more complex and intentionally messy scenes), and 3 has a quaint feel very typical of old Disney movies.
Thankfully, 3, the design decision that generalizes the worst, is only tied to a single principle, Appeal. So we can easily apply the rest without binding ourselves to 3. This is what has happened when animators outside of Disney applied the principle, and focused more on charisma than beauty for example, or went for true horror animation.
These design choices then shape a set of recurrent problems to solve for the animator:
How to animate in a way that feels alive?
How to make a scene as clear as possible?
How to make a scene interesting despite it being clear and focused?
And many more concrete ones, such as "How to stop a movement without the character reaching a weirdly static stand still?"
This leads us, at last, to the most practically relevant aspect of the 12 principles: the solutions to these problems! Or rather, the set of tools that the animator can use to tackle these problems.
These tools can take the form of knobs, that is explicit relevant degree of freedom (Squash and Stretch for compression and extension, Anticipation for preparing the next movement, Timing for the number of drawings in a movement...), or they can be constraints (Arcs for the shape of living movement, Solid Drawing for avoiding twins — overly symmetric drawings...), or they can be specific answers to practical problems (Follow-Through and Overlapping Action for what to do at the end of a movement, Secondary Action for giving more life to a very clear scene...).
We thus see that the 12 principles contain a whole language for the animator! They provide a model of movement and how it is perceived, explicit design choices about what matters in animation, convergent problems that appear across the field, and various tools to tackle these problems!
Once again, if you want to learn more about these principles from two masters of the craft, I highly recommend The Illusion of Life by Frank Thomas and Ollie Johnston.