An Introduction to Computer Animation

Dr Ian PalmerElectronic Imaging & Media

Communications DepartmentUniversity of Bradford

Outline

In the beginning Some computer graphics basics Digital animation in the entertainment

industry Special effects Animation

Today and the future

1

1979-20022

Early days

• Mid-nineteenth century: Zoetrope– Individual images on the

perimeter of a wheel– Wheel rotated and images

viewed through a fixed slot

• Turn of the century: Film– Allowed production

of individual frames– Winsor McKay’s

“Gertie the Dinosaur”

The birth of animation

• 1930’s: Walt Disney– Use of transparent cels to

produce layered images– Animation moves from

novelty to mass entertainment and art form

• 1930’s: Willis O’Brien– Stop-action model animation

in “King Kong” set a standard for special effects animation

Traditional animation

One hour of animation on film (24fps) requires 86,400 frames

If frames are generated one by one this is an enormous task

Key-framing was first used for feature length animation by Walt Disney ‘Master’ animators draw the key positions Less experience animators draw in-between frames

The use of computers

• 1970’s: First use of computers– New York Institute of Technology– 2D in-betweening– 3D in-betweening

• 1980-90’s: Advanced techniques– Motion capture– Dynamics and kinematics– Procedural and character systems

Some computer graphics basics

Computers must store models of objects to allow them to be animated.

Most models stored as a set of points that are connected together to form polygons, and then a number of polygons are connected to form a ‘mesh’

These object meshes can then be ‘moved’ through the 3D world - 3D animation

To show this on traditional displays (e.g. TV and film) a 2D picture has to be created of the 3D world - this is called rendering

All methods are based on some aspect of modelling the way light behaves

A common one is ray tracing which calculates how rays of light travel and are reflected from objects

Some computer graphics basics

Ray tracing

Animating

Once we have a way of creating objects and generating pictures of them, we need to animate them

We can key frame them in three dimensions

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First major example: Tron

1982: Disney produce a film which contains a substantial amount of computer generated imagery (15 minutes!)

Landmark in digital animation, but a commercial failure

3

After Tron

Digital animation retreated back into the research laboratory for the next few years

But another technique and landmark film hit the screens in 1982: The Wrath of Khan

Particle systems - a collection of small objects that combine to produce the desired effect

4

Particle system

• Some phenomena are made up of tiny particles, each of which is individually (virtually) invisible

• It is the combination of many thousands or millions of these particles that produces the effect

• Particle system is a collective name for the approach that attempts to approximate fire, smoke, etc. by producing a system of individual elements that collectively produce the desired effect

• There is no ‘surface’ as such (just as in a real fire the flames have no surface)

Meanwhile...

John Lasseter, inspired by Tron, was trying to convince Disney that digital animation was viable

Produced short animations, including the Oscar nominated Luxo Jnr (1986)

5

Back in the special effects department: The Abyss (1989)

Modelling of a fluid creature Modelling flexible bodies & reflections

Convinced John Cameron that SFX could play amajor part in a movie

6

1991: Terminator 2

Used similar techniques to The Abyss for many of the effects

Motion capture of actors Hollywood now

convinced - birth of the ‘SFX movie’

7

Motion capture

We can attach motion sensors to different parts of the body of an actor and then use the appropriate channels to drive the motion of parts of a character

When the actor moves, the character is driven in real time

1993: Jurassic Park

Behavourial modelling E.g. flocking of birds and animals

Each object must try and match the velocity of its neighbours whilst avoiding collisions and trying to remain close the the centre of the ‘flock’

Such animation makes the automated process of animated large numbers of (almost) identical objects much faster

8

1995: Toy Story

The first feature length digital animation (79 minutes) 114,240 frames 800,000 rendering hours 3.5 minutes a week produced on average

Example character: Buzz 34,846 lines of code 700 separate animation controls

Quality of Disney applied to a 3D world

9

1997: Titanic

Procedural modelling All modelling and animation is described by a

(usually text-based) scene file This is in a scene description language and is

usually created by using an interactive package initially but may be edited

The scene file contains procedures that define the animation, hence the name procedural modelling

10

1999: The Matrix

2001-3: Lord of the Rings

Combines state of the art techniques with older methods

Vast amount of special effects

Only now is it possible to create Tolkien’s vision

Today

Mass produced TV digital animation Starship Troupers, Max Steel, Excalibur…

Many SFX based movies (and many with little or no plot!)

Hugely successful CG movies: Finding Nemo the most successful animated film ever

Tools make it much easier to produce all kinds of computer animation...

11 & 12

Today & the Future

Driving forces are the film industry and the computer games industry

New tools and research are making the production process much easier

Complete virtual actors with autonomous behaviour