Stretch and Squash - Making the character compress and expand with the forces involved in the movement. This could be literally stretching and squashing a rubbery cartoon character. However, stretch and squash can be achieved without changing the characters shape by movement through the joints.
Anticipation - A minor, often opposite, movement that precedes an action. Anticipation allows the character to generate the necessary force to carry it through the action. It also prepares the audience for the action. The classic example of anticipation is crouching down before jumping. Without the crouch the character would seem to be being lifted off the ground instead of jumping under its own power.
Secondary Action - Parts of the character that attach to the moving body follow. Hair and clothing do not move on their own unless the character moves or they are acted upon by some other force. They follow the moving character instead of moving at the same time.
Overlapping Action - Related objects start and end their movements at different times. If every part of the character moves at the same time and same pace it looks unnatural. For example, when flicking one's wrist, the arm and hand move in opposite directions, the hand starts later and moves faster.
Follow-through - Things don't just come to a dead stop suddenly. The motion will continue as it decelerates. For example a batter doesn't stop swinging after he makes contact with the ball (or not) but continues through the swing,
Slow-in, Slow-out - Objects must accelerate before reaching full speed and must decelerate before stopping. Objects generally move fastest in the middle of an action and slower at the beginning and end.
Arcs and Trajectories - Objects in motion follow a path and do not suddenly change direction without a cause. Arcs and curves are beautiful to look at and see in motion.
Drag - Objects tend to remain where they are until moved by an a force.
Pacing - Characters do different actions at different speeds instead of every action taking the same amount of time. Varying the pacing prevents the motion from being monotonous.
Exaggeration - Animated characters can do much more than real life characters. Total realism is boring in animation. It is the responsibility of the animator to take things further.
Appeal - Character and motion should both be aesthetically pleasing. This is the hardest principle to define.
I have read these principles many times before. However, you don't really know the principles until you use them. As you can see, there is a lot of overlap in the principles. That is because all of these principles should be applied simultaneously in all character animation.
To help clarify these principles we were given four short exercises to apply the principles.
The first exercise is for the principle of drag. Here a spaceship is dragging a ribbon behind it.
The second exercise is secondary action. Here nun-chucks swing from a pendulum. The nun-chucks follow the primary action of the pendulum. I realize it is unrealistic for the nun-chucks to go higher on the second swing than on the first, but this is just an exercise and I wanted to try both a smaller movement and a larger one.
The Third exercise is for overlapping action. As the train hits the wall, when the front of the train is being pushed off the tracks the rear cars are still moving forward.
The forth exercise is for follow-through and secondary action. Here a ball is wearing a skirt. As it bounces it pulls the skirt with it. When the ball changes direction, the skirt continues its path until the ball pulls it the other direction. This was my favorite exercise.
Now these principles are applied to a character. This is exciting, after using the flour sac, to move onto a character with arms and legs. It is the next logical step since the character is basically a flour sac with arms and legs. The character looks very similar to Stitch from the Disney feature Lilo and Stitch, but he isn't; so don't sue me. Here, he jumps a couple times then falls on his face. The principle should all be in this animation and every animation I do for the rest of my career. A few example: Before he jumps, he crouches down, applying the principle of anticipation. When jumping, he follows an arc and moves slowest at the top of the arc. Here we see an arc, slow-in, slow-out and pacing. When he lands on the first jump, his force causes him to use his hand to catch himself, demonstrating follow-through. When he falls on his face, his hips land before his head and arms; then his hips bounce off the ground before the head. This demonstrates overlapping action.
