In real life, most actions have an arched trajectory. To achieve greater realism, animators should follow this principle. Whether you’re creating the effect of limbs moving or an object thrown into the air, movements that follow natural arcs will create fluidity and avoid unnatural, erratic animation.
To keep arcs in mind, traditional animators often draw them lightly on paper to use as reference and to erase when they’re no longer needed. Speed and timing are important with arcs, as sometimes they happen so quickly that they blur to the point they’re unrecognisable.
Of course, this is sometimes done deliberately, to give the impression of something unrealistically or amusingly fast. This is known as an animation smear. Chuck Jones, one of the greatest animators of the 20th century, was an expert at these. He was behind one of the first examples in a short for Warner Bros in 1942. Jones only used it to save time, but liked it and would return to the trope for many animations in the Looney Tunes series. It's still used today in The Simpsons.
8. Secondary Action.
This principle of animation helps emphasise the main action within a scene by adding an extra dimension to your characters and objects. Subtleties, such as the way a person swings their arms while walking down the street, give colour to your creations and make them appear more human.
Providing they don’t take attention away from the main action, secondary actions can really bring a scene to life.
As in real life, animation is all about timing. Get this principle right and it grounds your animation in realism, as everything will appear to follow the laws of physics. Think about the size and weight of your characters in relation to what and who are around them. A lightweight person or object is going to react quicker to being pushed than a heavy one.
To get your timing right in animation, get your number of frames or drawings right. As with the ease in, ease out animation principle, the slower the action, the more frames or drawings you’ll need to add.
This is a fine art and one that Disney animators are experts at. Many of the 12 principles of animation are grounded in realism and this is no exception. However, if you totally avoid exaggeration, animation can often be too real and is in danger of looking dull.
Disney believes that exaggeration should be true to reality to an extent, but made more extreme - often pushed just beyond the realms of realism, to make their characters pop and add fun to their adventures.
A classic trope and great example of exaggeration in animation is the jaw drop. When a character is surprised, shocked or falls in love at first sight, animators often don’t just show a slightly stunned, open-mouthed expression. They get their point across by showing their character’s mouth dropping way beyond realism - often literally to the floor.
11. Solid Drawing.
Solid drawing in animation is one of the more difficult principles to get right, especially in traditional animation. This is because you need to make your creations feel 3D and give them weight and volume. Art classes are useful to give you deeper knowledge of weight, balance, gravity, light, shadow and more. In The Illusion of Life, Johnston and Thomas warned of the danger of creating ‘twins’, where characters would appear lifeless because their left and right sides were exactly the same.