Animation May 2008

Computer animation Animation: make objects move or change over time according to scripted actions and/or (physical) laws

Animation Animation is produced by the rapid display of consecutive still images. For a smooth visual effect, higher frame rates may be necessary, and timing of frame displaying is important.

Types of animation Hand-drawn Stop motion Animatronics Performance animation (mocap) Virtual models Effects

Early animation Early 'real' animation: creating each frame of a real scene by hand = stop motion animation. Example: King Kong (1933), hybrid of animatronic and stop motion animation.

Traditional Animation Animators work from storyboards Gross timing (usually) determined by dialogue soundtrack Older animation: –Static background –Characters painted on cels –Lead animator creates key frames –Second animator creates in between frames (inbetweens)

Traditional animation Many of the esthetic animation principles from traditional animation can -and often should- be applied in computer animation. Computer animation tools enable just about anybody to make an animation. Computer animation tools enable just about anybody to make a bad animation.

Traditional animation Fundamental principles of traditional animation (Disney): 1.Squash and stretch 2.Timing 3.Anticipation 4.Staging 5.Follow through and overlapping action 6.Straight ahead action and pose-to-pose action 7.Slow in and out 8.Arcs 9.Exaggeration 10.Secondary action 11.Appeal

Squash and stretch Movement shows rigidity of an object - soft objects deform more. Squashing and stretching emphasize natural movement, object rigidity and movement speed. Squash and stretch should preserve volume. Laws of physics may be broken (e.g. stretch before impact). Squash and stretch need not deform the object.

Squash and stretch Example with deformation

Squash and stretch Example without deformation

Squash and stretch Example?

Squash and stretch Squash and stretch helps avoid strobing effects.

Squash and stretch

Timing Timing is the speed of an action. It is an action generally consists of three phases: anticipation action Reaction Timing helps define an action (see next example).

The many meanings of a simple head turn.

Timing Proper timing is critical to make the audience understand an action: time the phases (anticipation/action/reaction) so that the action is understood (not too short!) without losing attention (not too long!). Timing defines weight of objects and characters –light objects move quickly –heavier objects move more slowly

Anticipation Anticipation is the preparation for an action.

Anticipation Often anatomical necessity. a muscle must extend before it can contract. no anticipation gives an unnatural movement. Prepares audience for an action. you know what is going to happen. Draws the attention. action is not missed and can be faster.

Anticipation Amount of anticipation (combined with timing) can affect perception of speed or weight. Light & FastHeavy & Slow

Staging Staging is the presentation of an idea so that it is clear. This idea can be an action, a personality, an expression, or a mood. –Actions are staged so that they are understood. –A personality so that they are recognizable. –An expression so that it’s visible. –A mood so that it affects the audience. For good staging the audience’s attention must be where it needs to be. Staging, anticipation and timing are crucial to leading the eye.

Staging Stage only one idea at a time (or it might be ‘upstaged’). Contrast the object of interest with the rest of the scene. The animator must use different techniques to ensure that the viewer is looking at the correct object at the correct time.

Staging For example, in Luxo, jr. The Father appears first, and so is the center of attention. Then the son bounds in, moving rapidly, so the center of attention shifts to him. At a certain point the son stops and looks up at the father, refocusing the attention on the father.

Staging In the early days at Disney all characters were black and white, with no gray. All action was shown in silhouette (to the side), because if a character moved its black arm in front of its black body it would disappear, so the action had to be against the white background. The Disney animators realized that even without this technological limitation action was more clearly visible in silhouette.

Staging Even with modern color 3D graphics, silhouette actions are more clearly delineated and thus to be preferred. over frontal action. An example would be a character waking up and scratching its side, it is easier to understand what it is doing than if it scratched its stomach.

Staging Staging is much clearer when done entirely in good silhouette. All parts are visible in the left picture Some are invisible in the right one (like one of the arms).

Staging

Show Luxo jr. Movie t_320.html

Follow Through and Overlapping Action Follow through is the proper termination of actions. Actions rarely end suddenly. An example is in throwing a ball - the hand continues to move after the ball is released.

Follow Through and Overlapping Action Most movements in an action are not simultaneous; there is a ‘lead’ and there are movements that follow (or drag) behind. In the movement of a complex object different parts of the object move at different times and different rates. For example, in walking, the hip leads, followed by the leg and then the foot. As the lead part stops, the lagging parts continue in motion.

Follow Through and Overlapping Action Heavier parts lag farther and stop slower. An example is in the antennae of an insect - they will lag behind and then move quickly to indicate the lighter mass. The movements may overlap in time. Overlapping means to start a second action before the first action has completely finished. This keeps the interest of the viewer, since there is no dead time between actions.

Follow Through and Overlapping Action Here is a quote about overlapping from Walt Disney: "It is not necessary for an animator to take a character to one point, complete that action completely, and then turn to the following action as if he had never given it a thought until after completing the first action. When a character knows what he is going to do he doesn't have to stop before each individual action and think to do it. He has it planned in advance in his mind."

Follow Through and Overlapping Action Show Movie mples/walk7.html

Straight Ahead and Pose-to-Pose Straight Ahead Action: –The animator starts at the first drawing in a scene and then draws all of the subsequent frames until he reaches the end of the scene. –This creates very spontaneous and zany looking animation and is used for wild, scrambling action.

Straight Ahead and Pose-to-Pose Pose-to-Pose Action –The animator carefully plans out the animation, draws a sequence of poses, i.e., the initial, some in-between, and the final poses. –then draws all the in-between frames (or another artist or the computer draws the in- between frames).

Straight Ahead and Pose-to-Pose This is used when the scene requires more thought and the poses and timing are important.

Straight Ahead and Pose-to-Pose This is similar to key-framing with computer graphics but it must be modified slightly since the in-betweens may be too unpredictable. For example, objects or parts of objects may intersect one another. Computer key-framing can take advantage of the hierarchical model structure of a complex object.

Straight Ahead and Pose-to-Pose Different parts of the hierarchy can be transformed at different key-frames. For example, in a jump, translation key- frames can be set for the entire model in the X and Z directions. Then other rotation or translation key- frames can be set for portions of the model, e.g., the legs and arms.

Slow In and Out A movement between two extremes is usually presented best when the movement is slowest at the extremes. May not be physically correct. Allows the viewer a little more time at the (interesting) extreme poses. Implemented by non-linear timing of the in- betweens.

Slow In and Out Rather than having a uniform velocity for an object, it is more appealing, and sometimes more realistic, to have the velocity vary at the extremes. Example1: No Slow-in Slow-outNo Slow-in Slow-out Example2: With Slow-in Slow-outWith Slow-in Slow-out

Slow In and Out Another example: A bouncing ball moves faster as it approaches or leaves the ground and slower as it approaches or leaves its maximum position. The name comes from having the object or character "slow out" of one pose and "slow in" to the next pose. Demo

Slow In and Out This is usually achieved by using splines to control the path of an object. The various spline parameters can be adjusted to give the required effect. In 3D Studio this is controlled by the parameters Ease To and Ease From in the Key info window (from the Track info window).

Slow In and Out When these are zero, there is a constant velocity in either direction, i.e., to/from the keyframe. When Ease To is set to a higher value, the motion is faster as it leaves the previous keyframe and slows as it approaches the current keyframe. When Ease From is set to a higher value the motion is slower leaving the current keyframe and speeds up as it approaches the next keyframe.

Slow In and Out The tick mark spacing shows the velocity with closer tick marks indicating a slower rate and spaced out ones indicating a faster rate.

Exaggeration Exaggeration of the motions that identify an emotional state makes this state easier to see. Do not arbitrarily distort object or actions, amplify only that which enhances the underlying reason for a motion. If only one thing is exaggerated then it may stand out too much. If everything is exaggerated, then the entire scene may appear too unrealistic.

Exaggeration

Secondary Action This is an action that directly results from another action. Actions have consequences. These should be part of the animation to enhance a realistic complexity. Should in general be kept subordinate to the main action, to avoid detracting attention.

Secondary Action An example might be the facial expression on a character. The body would be expressing the primary action while the expression adds to it. Another example would be the trailing electrical cord of Luxo, jr. Demo

Appeal Appeal means something that the audience will want to see. This is equivalent to charisma in a live actor. A scene or character should not be too simple (boring!) or too complex (can't understand it). One principle to achieve this is to avoid mirror symmetry. Asymmetry tends to be more interesting and appealing. Demo