3D Art Essentials: Chapter 8 "Animation - It's alive!"

These are my notes from reading chapter 8 of 3D Art Essentials by Ami Chopine. I have included notes from nearly all of the subjects she talks about, but have only included bullet points that are useful to / interest me. I have also highlighted important parts which I will need to remember especially for my animation.

There is a practical task at the end of the chapter which I will do in another blog post later this week.


The Twelve Basic Principles of Animation

• 'The purpose of animation is to serve the story - to capture images of life, and in the process communicate to others, even if it just means giving them a thrill ride'.
• Animators at Walt Disney Studio wanted animation to feel real and allow audience to respond to character and story.
• They developed a set of animation guidelines which are still used to this day, though modified for computer animation.

Squash and stretch

• This is the most important principle.
• Bouncing ball is an example: as it hits ground it squashes, but its volume must stay the same, and it therefore stretches.
• Squashing and stretching give weight to objects.
• Isn't limited to balls and tummies, and collision with floors or objects is not required.
• These movements happen in facial expressions, and any other kind of motion.
• Bodies have weight and respond to gravity, they must retain their volume.

Anticipation

• Iron Man crouches and places hand on ground, and you know he's about to spring into action; this is an example of anticipation.
• It helps audience clue in that something will happen next.
• Anything which invites audience to watch what happens next is anticipation.
• If there's no anticipation, it can surprise the audience, if nothing happens, it's an anticlimax.
• Understanding this can help move story forward, set up comedic effects, or startle audience.

Staging

• Art of communcating idea clearly through imagery, be it personality, a clue, a mood, foreshadowing, etc.
• Is done with how character, objects and surroundings are presentated.
• Don't have anything unnecessary in scenes, or it will lose focus.
• Not real life, it's life through a filter; it is emotion, conflict, resolution.
• With computer animation, you have control over everything in scene and character, expressions, gestures; use this to your advantage.
• Staging can also be set in postproduction, with lighting and colour adjustments. 

Straight-Ahead Action and Pose to Pose

• Styles of drawing your animation
• Straight-Ahead is animating frame by frame, it's good for dynamic action and spontaneity
• It can be bad because when hand-drawn, proportions and volume are lost, and you may end up at a dead end.
• Pose to pose let's animator carefully plan animation, draw key poses, then fill in movement between.
• Computer animation makes pose to pose natural, computer fills in movement between key poses.
• Motion capture and dynamic simulations are straight-ahead action.

Follow through and Overlapping Action

• When things like hair, clothing and loose flesh continue moving after character stops, it's called follow through.
• Could also be when characters move and things must catch up, or the expressive reaction of character to their action.
• Overlapping action is when things move at different rates, ie head turning whilst arm is moving

Slow In and Slow Out

• Action never stops instantly, or it's too robotic.
• Action starts slowly, speeds up, then ends slowly.
• Leave out slow in and slow out for surprise or comedy gags.
• Graph editor is good for creating this motion.

Arcs

• People, creatures and sometimes objects move in an arc.
• Try waving arm / hand, you can trace the arc it moves in.

Secondary Action

• Hair, clothes and background leaves are secondary actions to main character.
• They can be good for setting the stage.
• Can also show personality, such as how a character moving their arms while walking.
• If it distracts from main action, you need to eliminate or rethink it.

Timing

• Physical action is making sure the right actions occur at the right pace, in consistence to laws of physics.
• Cruise ship going to take longer to get under way than small yacht.
• Story timing is each shot, scene, and act; a part of both acting and storytelling.

Exaggeration

• Taking reality and making it more extreme.
• Realistic action and visuals fall flat when illustrated.
• Can be used for comedy, superheores, portraying mood, etc.
• Body, head shape, expressions, action, aspects of setting, storyline, anything can be exaggerated.

Solid Drawing

• Important to know where each muscle is placed before can be bulged out.
• Reference real life.
• Even if just interested in 3D art, take drawing classes and learn proportion, composition, perspective.

Appeal

• Characters need to appeal to audience.
• If not sympathetic, villains can look cool.
• Has to do with features you give them, clothing, facial expressions, the way they act towards others.
• Symmetry is considered beutiful by people.
• Features that parallel the young (large head to body, large eyes, get more sympathy).
• For less sympathy, go opposite, with small beady eyes and narrow head.
• Must be believable, must be clear, audience must care about characters.

Keyframing

• Images that make up motion picture when sequenced are called frames.
• Typical framerates are 24 to 30 fps
• In 3D animation, computer renders each frame based on models, lighting, background etc and how you direct their movement.
• With keyframing, you define start, middle and ending positions and attributes of objects.
• Example of Susuan throwing a ball: start frame is when ball is in cocked hand, ending keyframe is when arm is stretched forward.
• Computer figures out frames that go between the key poses.
• New keyframes would need to be added to show the balls arc.

Animating with Graphs

• When you place keyframe, this will become a point on an animation graph.
• For the x axis of the graph you have the timeline, for y axis, the numeric value of object's attributes and position are shown.
• Computer interpolates between frames, and animation graph is where you see the values of the interpolation,  drawn as lines of curves.
• There are three main types of interpolation.
• Stepped interpolation don't change until next keyframe, resulting in instant change from one to next.
• Linear interpolation connects keyframes by lines, giving smoother but still jerky movement.
• Curved interpolation connects points by curves, movement can be eased in and out to change speed.
• Manipulating curves on graphs is good for more exact animation, but should be used in conjunction with 3D view animation.

Motion Capture

• Motion capture lets a performer drive the animation of a character.
• Actor wears suit covered in lots of markers, sometimes on face for facial animation.
• Multiple cameras film them acting, then translate it into 3D space using markers.
• Rig must match up with actor well enough to give accurate data.
• Problems such as interacting limbs, body and face different from actors, and plain errors in capture.
• Animators must clean this up as well as exaggerate or enhance some poses, making it a collaboration between actors and animators.

Facial Animation

• There are six universal expressions: happiness, surprise, disgust, fear, sadness, and anger.
• Study expressions and get them right to avoid the uncanny valley, where expressions are close but not quite realistic, making the audience feel revulsion.
• Rig should involve deformation, skeleton rig with the jaw, good underlying topology.
• Use facial rig to create expressions called morph targets, which use sliders to move between two morphs.
• For talking, the sound of speech can be broken into phonemes.
• The shapes of jaw, tongue and mouth must make for phonemes can be called visemes.
• Problem with visemes is that they blend together during speech.
• Using sliders for morph targets and keying blended viseme in, can achieve more realistic speech.
• Important for mouth animation to sync to recorded speech.
• As well as speech track, you will have each sound plotted out to each frame.

Automation

• Lots of motion in animation can be automated.
• You can link any kinds of characteristics of objects to each other.
• The position of a switch can determine if light in the scene is on.
• As a cart moves forward, the wheels can turn at a rate which matches distance travelled to circumference of the wheel, making the wheel turn in time.
• Can also add animation without keyframing with dynamics and scripting.

Fence-Post Errors

• When filming at 24fps, a frame is captured over 1/24th of a second.
• In computer animation a rendered image only represents a point in time with 1/24th of a second between each frame.
• Can create fence-post errors, like when time is no longer moving forward so computer does not add motion blur where it needs to.
• Usually up to animator to correct such problems.
• Frames should be thought of as periods of time, not points in time.

Animation Workflow

• First few steps of a good workflow happen away from the computer.
• Should have a script by this point, may have a storyboard.
• During brainstorming, gather reference videos and pictures.
• Act out the motions yourself and get a feel for how it should go.
• A good animator is an actor who uses computer for their performance.
• Draw quick thumbnail sketches of ideas for poses, emphasis on quick as they are disposable.
• Brainstorming means quantity, not quality.
• Draw a pose, if it doesn't work, throw it out.
• These are key poses, and you need to consider timing of poses.
• Can arrange poses on exposure sheet (or 'dope sheet').
• Exposure sheet is used to write instructions for each frame, which gives a rough idea of timing.
• Once complete, get back to computer, take rigged model, and keyframe all poses.
• Work with heavy things first: legs, torso
• Work your way from main parts and big motions to tiny motions and facial expressions.
• Once all key poses are present, do a preview render whilst in stepped mode.
• Look at the timing and refine the pose positions.
• Character moves into poses at the same time, looking robotic.
• Could create more poses, the traditional method, gives more visual control and may save time with organization.
• Other method is modify poses using animation graph, to offset parts of the model.
• Don't render each section as you progress, refine whole shot then do another test render.
• Though most work is on refinement, if others can't see what's wrong, then it's fine.
• Some production houses have high quantity output, not quality; though something isn't good enough for you, it can be good enough for them.
• Most animating will be done with low poly versions of characters, as 3D modellers aren't finished; tweaks could be deleted and redone when final version is imported.
• Don't lose sight of the art, even if computers can do stuff for you, you may want to do it yourself; the computer has no heart or even a brain.