03 Principles

7/28/2019 03 Principles

1/29


2/29

CMPT 466 Summer 2013 Hao (Richard) Zhang2

Reading

R. Parent, Computer Animation: Chapter 1 J. Lasseter, Principles of Traditional Animation

Applied to 3D Computer Animation, Computer

Graphics, 35-44, 21(4), 1987 (SIGGRAPH 87) Course #1 at SIGGRAPH 1994:Animation

Tricks

K. Laybourne, The Animation Book, CrownPublishing, 1998

T. White, The Animator's Workbook, Watson-Guptill, 1988


3/29


Overview

Some principles of animationAnimation production


4/29


Principles of animation

Principles gained from hand-drawn animation From original animators of Disney, e.g., Lasseter Combining the physical and the artistic Each principle can be implemented by associated

computer animation techniques


5/29


Principles: simulating physics

Not true physics simulations to look right andsometimes with exaggeration

A lot of examples (following list only partial) Pick the most visually important Experiences gained from traditional animation

Physics based animation attempts to model themore complete set of physical principles


6/29


Simulating physics

Squash & stretch Distortion of shapes to emphasize motions It really happens, but here a form ofexaggeration To better reflect non-rigidity/mass/weight/volume

of the animated objects

E.g., bouncing ball, bodyweight of character walking

Perhaps the most importantelement to master


7/29


Simulating physics

Timing How actions are spaced across time, reflecting

characteristic or even personality of object/actor

E.g., heavy object moves slowly Slow-in (ease-in) and slow-out (ease-out) of

motions more natural and physically plausible

A lot coming from experience and observations


8/29


Simulating physics

Secondary actions Physically based reaction to support main action that

is primarily modeled

E.g., movement of skin or hair during movement ofhuman characters (can always exaggerate)

E.g., an angry walker moving the legs (main motion)

must be supported by movement of arms and heads Even modeling of reaction of other objects/actors


9/29


Simulating physics

Slow in & slow out --- example of timing How things move through space Objects slow in and slow out of poses, to model

inertia, friction, viscosity More drawing at start and end of motion sequences

Arcs: Movement often in arcs (not straight line) due to

gravity or underlying physical structure E.g., think of movement of arm, leg, fingers


10/29


Principles: aesthetic actions

Exaggeration Grab attention or make a point Very frequent, e.g., squash & stretch

Appeal Make it enjoyable to watch

Follow through and overlapping action Actions flow into another, continuity, e.g., squash & stretch

Solid drawings: to give illusion of 3D


11/29


12/29


Principles: presentations

Staging Directs the audience's attention to the story or idea being told so

that it is not missed by the audience

A pose or action should clearly communicate to the audience theattitude, mood, reaction or idea of the character as it relates to

the story and continuity of the story line.

The effective use of long, medium, or close up shots, as well as

camera angles also helps in telling the story.

Do not confuse the audience with too many actions at once.


13/29


Principles: production

Straight ahead Develop motion continually, first to last Principle followed by physically based animation

Pose-to-pose Identify key frames and then go back to interpolate Typical in conventional animation

Principles of film-marking, see Section 1.3.2


14/29

CMPT 466 Summer 2013 Hao (Richard) Zhang

Some examples

Three point lighting

180-rule Rule of the third Camera distance and angles

14

Key light

Above camera; high-intensity; shadow

All three lights

together

Rim light

Behind camera;brings objects out

of background

Fill light

Below camera;flood light; details


15/29


Animation production

Elements of a production: 4-level hierarchy Production

Entire animation Sequence

Major episodeAssociated with staging area

Shot

Continuous camera recording Frame: single recorded image


16/29


Animation production pipeline

A trial-and-error process with feedbacks between steps Preliminary story / script

Storyboard: sketches of representative frames Sheets:

Model sheet (character details, e.g., in diff poses) Exposure sheet (camera details, soundtrack cues) Route sheet (statistics and responsibilities of scenes)


17/29


Storyboards


18/29


Animation production pipeline

Animatic (or story reel) Recording of storyboard frames Each storyboard frame lasts as long as the corresponding

sequence

Presents a rough feel of timing (and story) Detailed story

Key-frames: chief/master animations job In-betweenings: associate/assistant animators job


19/29


Computer animation production

Very much mimicking theproduction pipeline of

traditional animation

Some differences, e.g., Clear separation of different

computer graphics tasks for

reuse, e.g., modeling, lighting

Use oflevel-of-details

Modeling dept.

Lighting dept.

Shading dept.

Animation dept.

Camera dept.

Layout dept.

Art dept.

Story dept.

Actual rendering

of the frames

Visuals and story reel

Lighting and appearance,

2D-to-3D, staging,


20/29


Post-production: video editing

Use of digital representation of films/frames Digital images can be copied without loss Analogue converted to digital

In the older days: Cutting and splicing tapes (physical medium): non-linear editing

(can follow any order) but tedious

Digital linear (electronic) editing: besides being linear, physicalwear and loss of quality due to physical tape copying process


21/29


Electronic editing

Output is assembled in

sequential order

linear editing


22/29


Digital non-linear editing

Flexible cut, drag,drop, overlap, etc.


23/29


24/29


25/29


Cinelerra


26/29


27/29


Video compression

Why do we need it?

The so-called true high definition video mode, 1080p, supports

a screen resolution of 1920 1080. Suppose that the video

content is to be displayed at 30 Hz and that we wish to provide

24 bits of color (8 bits per R, G, B). Then how many seconds of

video of this type could fit on a single-layer HD DVD, which has a

storage capacity of 15 Gigabytes?

Answer: 80 seconds!


28/29


Video compression

Codec (compression/decompression) Symmetric codec Equal time for compression and decompression

Typically, decompression has to be real-time Lossy vs. lossless Interframe vs. intraframe compression


29/29


Codecs

Compression methods Runlength encoding (stores runs of same data as

a single instance plus count; useful for animation)

Vector quantization Digital cosine transform (DCT = JPEG) Wavelet compression

Examples MPEG, DivX, etc

03 Principles

Documents

Transcript of 03 Principles