The Principles of Animation
People often talk about “computer animation” and “3D animation” as if they are something completely new, but this is not the case. The only thing that’s new is the medium, i.e. the tools used to create it. Yes, it may be “3D” and it may be created on a “computer”, but it is still animation! Luckily for us, animation has been around for decades, and a lot has been learned about how to make good animation. Probably the most influential discoveries were made by Walt Disney and his team during the early days of the Disney studio. Their quest to truly bring to life their animation is documented in the book “The Illusion of Life” by Frank Thomas and Ollie Johnston, and it is from their findings that the “12 principles of animation” were established.
Not
all of these principles are completely relevant to 3D computer animation, but
most of them are, so I will concentrate on the most important ones.
Here’s
a quick quote from John Lasseter of Pixar Animation Studios (Toy Story, A Bugs
Life etc) just in case you don’t believe me…
"When
I presented the first animation I had created with a computer, "The
Aventures of André and Wally B.," at Siggraph ‘84, a number of people
asked me what cool new software I had used to achieve such believable
characters. I explained to them that the software was a key frame animation
system, not much different in theory than other systems that were around then.
What was different was that I was using basic animation principles that I had
learned as a traditional animator. It was not the software that gave life to the
characters, it was these principles of animation, these tricks of the trade that
animators had developed over fifty years ago. I was surprised at how few people
in the computer animation community were aware of these principles".
-
John
Lasseter
Taken from Course 1 at SIGGRAPH 94,
"Animation Tricks".
Read the full article HERE
So,
now that we’re all convinced of the need for animation principles, let's find
out what they are…
The
12 principles of animation are:
1)
Squash and Stretch
2)
Anticipation
3)
Follow Through and Overlapping Action
4)
Arcs
5)
Slow In and Slow Out
6)
Timing
7)
Secondary Action
8)
Exaggeration
9)
Staging
10)
Straight Ahead Action and Pose to Pose
11)
Solid Drawing
12)
Appeal
Squash and Stretch
When an object moves,
unless it is completely rigid, it will deform as it moves.
This is especially true of things composed of living flesh. For example,
when a character is crouching down, his body becomes squashed, and then when he
leaps into the air his body becomes stretched. One thing that is important to
remember is that no matter how much the character squashes or stretches, he must
always maintain the same volume. The amount of squash and stretch will depend on
the pliability of the material concerned. Traditional animation usually contains
very exaggerated amounts of squash and stretch. In 3D animation people tend to
be a bit more reserved in their use of exaggerated squash and stretch, as it
doesn’t always complement the realism of the medium. A good example of squash
and stretch is a bouncing ball: when it hits the ground it squashes, and the
then it propels itself up again by stretching.
Anticipation
People watching your
animation will not understand the actions taking place on screen unless they are
expecting them. It is up to us to create a clear sequence of events that lead
from one action to another. We can do this by preceding each action with a
movement that anticipates the action for the audience, so that when the action
actually occurs, they are ready for it and expecting it. Confused? It’s really
very simple! Sometimes, the anticipation move is something that we physically
cannot do without. For example, stand with your feet together and then jump
forward. The jump was the action, but before you can jump, you simply have
to crouch. Try jumping without crouching. You can’t do it can you?! However,
when we’re animating, we can jump without crouching, but it just
won’t look real. As well as anticipation being something that can be
“physically” required, most of the time we just use it as a theatrical tool.
It is used to make sure each of our actions creates maximum impact. Most actions
take place very quickly, and if we do not give the audience time to prepare for
the action, they may miss it completely.
Follow
Through and Overlapping Action
“Things do not come to a stop all at once…; first there’s one part and then another”.
-
Walt Disney
This is quite a complex
principle, so it is broken down into a few different sub-headings. The
fundamental idea behind all of these is that different parts of an object will
move at different speeds depending on their mass.
A: Appendages
Appendages such as a
cloak or long flowing hair will “lag” behind a character due to their
lighter mass, and will continue to move after the character has stopped.
B: The Body
The body does not all
move at once. The arms, for example, will continue to swing after the body has
stopped. If a character suddenly turns to his right, first his head will move,
then his shoulders, and then his arms will follow. When the head and shoulders
stop, the arms may still be swinging around to catch up with them. Then, if the
character suddenly turned to look in the opposite direction, the arms could
still be moving in their initial direction before they are affected by the new
movement. This is what we mean by “overlapping action”.
C: Loose Flesh
The loose flesh on a
character must move slower than the skeletal parts. We sometimes refer to this
as “drag”.
D: Completion of an
Action
The way an action is completed can
often reveal far more about a character than the action itself. The action
itself happens very quickly, whereas the aftermath can take as long as you like.
E: The Moving Hold
This is really important
so listen carefully! In order for the audience to really absorb a certain pose
or expression, it is often necessary for us to hold that pose for a short while.
However, if you just freeze the character, then he no longer looks alive. Living
things just don’t stay still!! So, those clever people at Disney developed
something called the “moving hold”. This involved taking two very similar
poses, one slightly stronger/more extreme than the other, and then interpolating
between them. By doing this, we
hold a certain pose, but the character never stops moving.
Acceleration
and Deceleration (Slow in Slow Out)
In the real world,
nothing really moves at a constant speed. The best example to explain this is
once again the bouncing ball. Imagine this: we hold a ball 30cm from the ground.
We then drop the ball.
The first thing that
will happen is that the ball will begin to accelerate because gravity is
affecting it.
Then it will hit the
ground travelling at top speed. When it hits the ground it will squash, and then
propel itself back up into the air almost immediately and at much the same
speed.
Then gravity will
begin to affect it again, this time making it decelerate, until it eventually
comes to a standstill and the process begins again.
So, we can see that
there is a lot of acceleration and deceleration going on. Now consider this
picture:
This picture shows a
bouncing ball at 2 frame intervals. Notice how the images get closer together at
the top. This is because the ball is moving slower at the top, and therefore
covers more frames. On the other hand, when the ball bounces off the ground, it
all happens very quickly, so only covers a few frames. The top of the bounce
would be considered “Slow In – Slow Out”, while the bottom of the bounce
would be considered “Fast in – Fast Out”. These kinds of affects are
achieved by adjusting the animation curves (Function Curves) of the object.
Arcs
Almost everything in the
natural world moves in arcs. There are two major reasons for this:
1: Rotational Joints
Your body is made up of
a series of rotational joints, so when you move your body, it’s actually the
result of your various limbs rotating around your joints. Because of this, our
movements tend to follow arcs. A
human walk cycle is full of arcs. The body moves up and down, as well as moving
forward, tracing an arc through the air:
2: Gravity
Gravity also causes
objects to move along Arcs. Take the example of the bouncing ball. If you throw
it forward, it is also pushed down by gravity, making it move in an arc.
The main lesson to learn
from "Arcs" is to try and avoid having any truly linear motion in your
animation unless it is mechanical.
Timing
Timing is one of the
most crucial aspects of animation. Even very small changes in timing can
completely change an animation. I like to think of timing in two different
categories: “Physical Timing” and “Theatrical Timing”.
Physical timing:
This is to do with the
world of Physics. The timing of an object can be affected by a great deal of
real world physical laws. Its weight is always a huge factor in determining how
it should move. Gravity is another. All of this kind of timing is basically
trying to make an object's movement “physically” believable.
Theatrical Timing:
This is more concerned
with the meaning of an action. All character animation is basically striving to
make the audience believe that a character is actually thinking, and that the
characters actions are the direct result of his thoughts. Tiny changes in the
timing of an action, or the pause in between actions, can dramatically alter the
meaning of that action.
Consider the following action: A man turns his head and looks
behind him.
Now ask yourself WHY?
Why did he turn his head? The answer will determine the timing.
Here are 3 scenarios for
a character. Act out each one and note the difference in the timing of the
action:
Scenario1: He is waiting for a bus and he is bored. He wonders if there is anything interesting to look at behind him. He looks over his shoulder.
Scenario 2: He is a burglar about to break into a house. He wants to make one last check that there is no one behind him watching. He looks over his shoulder.
Scenario 3: He is in a house full of vampires. He suddenly heard a snarl right behind him. He looks over his shoulder.
All of these actions should be different. I could talk for hours about this, so I’d better stop! I think you get the idea.
Secondary Action
Secondary actions are the little extra touches that you add in after you have created the main actions, just to bring your character to life even more. For example, your character is reading a book. He is studying the pages intently. The main action here is him looking at the book, and maybe running his finger across the page and moving his eyes. However, why don’t we also have him scratch his chin and then push his glasses up his nose? The important thing to remember is that the secondary action should never detract from the main action; it is just there to support it. Some people also tend to refer to some of the movement discussed in “follow through and overlapping action” as being “secondary motion”; for example, you might animate an alien’s head, and then afterwards animate his antenna waving around as well.
Exaggeration
Exaggeration is an important part of most animation. It is used more in traditional 2D animation, and is sometimes not used at all in 3D these days, for example “Final Fantasy: The Spirits Within”, where the goal was ultra realism, and exaggeration would not have worked. However, most of the time, it’s best to overstate everything in an animation, or the audience tend to miss it. A character’s pose should be exaggerated at least slightly to make it clearer to the audience.
Staging
Staging is extremely important to all animation and film making practices. It’s almost impossible for me to discuss staging in any kind of detail here, but I’ll just try and sum it all up in one sentence for you!
Every shot should be staged in such a way that the message of the shot is as clear as possible.
To find out more about The Principles of animation, try these links:
Siggraph paper on the Principles of animation (Good coverage of all principles)
Speech by John Lasseter of Pixar (speech by John Lasseter on creating thinking characters)
Michael Comet's breakdown of the Principles (good site, easy to follow, with pics and demo movies)
Please do go and look at those sites, as everyone has a slightly different way of explaining these principles, and you can learn something new from each.
Also check out my Links section, as there are 100's more sites with useful info about animation principles.
Right I think that’s enough for one day. Just remember, these are only principles, the magic happens when you actually put them into practice!