computers in film making

Computers in Film Making

Snow White (1937)

Computers in Film Making Slide 1

Snow White - Disney’s Folly

Original Budget $250,000Production Cost $1,488,422Frames 127,000Production time 3.5 years

but

Gross revenue $184,925,486

Moral:

• Animated films are high risk, but very profitable

• Creation of these films required enormous human input

Computers:

• Could automate some of the human tasks


212D Graphics - Tweening

By the 1970s computers were sufficiently powerful tohelp with drawing cartoons, and assembling “cell based”animation.

Some work was done to support “tweening” - drawing theframes that go between two keyframes - but this provedhard to automate.


3D Animation - Polygon rendering

Military simulator circa 1990

Early computer animationsystems (flight/militarysimulators) used planarpolygons to create 3Dworlds.

Costs were high and thequality was too low forfilm.


The Graphics Pipeline: 1980


Silicon Graphics Reality Engine (1992)

Nowadays you can buy afar more powerful Graph-ics Processing Unit to pluginto your PC.

Special purpose hardwarefor interactive graphics

OpenGL: General purposedesign language


Polygon Rendering in films

Toy Story (1995)


Ray Tracing (1980)

Each pixel of the image is computed independently

Reflections and refractions can be created.


Ray Tracing Examples

morphine molecule (1983)



Street Scene (2011)



Titanic (1997)


Gorilla Filmstars - are they Computer Generated?


Gorilla Filmstars - are they Computer Generated?

King Kong 1976 King Kong 2005 Real Gorilla

Real Gorilla King Kong 1933 Trading Places 1989


Motion Capture

One approach to createrealistic movement is to usemotion capture - for exampleGollum in the Lord of theRings films.

The actor’s movements arefilmed and turned into 3Dmovements, then mapped tothe avatar.

The Fellowship of the Rings 2001


Complexities of Motion

Natural motions arecomplex, as shown byEadweard Muybridge’shorse photographs of(1878).

Both the geometric mo-tion and the dynamics(velocity and accelera-tion) are difficult to de-scribe.


Skeleton based Animation

The skeleton geometry is well defined and constrains themotion.

However there are many different types of joints.


Inverse Kinematics

One approach to moving a skeleton is to specify how theextema (hands feet) move, and calculate the positions ofthe other joints. Each link is specified in the coordinatesystem of its predecessor

However there is no unique solution, so there is an openresearch question - How do we constrain the solution toachieve natural movement?


Amorphous Objects

A major challenge for the com-puter scientist was (and stillis) creating amorphous movingobjects such as fire, smokeclouds and water.

The problem has two aspects:

• modelling• rendering


Particle Systems

One modelling method is to ap-proximate amorphous objectsby a discrete set of small par-ticles. Particles can have:

• Mass• Position• Velocity• Temperature• Shape• Lifetime

Particle Fountain


Particle Fires - The Wrath of Khan (1983)

Particle systems were first usedin film to create fire in the film“The Wrath of Khan”.

The Genesis Bomb:

• A special bomb is droppedon a baren planet

• The bomb and fire createlife on the planet

(Doesn’t sound very likely to me)


Rendering Particle Fires

The Wrath of Khan renderedeach particle by drawing a lineshowing its path during eachframe.

The line was temperaturecoloured:

• Yellow -very hot• Red -hot• &c.

This worked well in long shotsbut poorly in close up.


Ray Tracing Particles

More realistic rendering, includ-ing translucency, can be doneby ray tracing the particles

• Particles are given a radius

• As the ray passes through aparticle sphere it takes onsome of its colour.

• Rays that miss all theparticles take on thebackground colour

• Rays that pass through a fewparticles mix their colour withthe background


Fluid Fires

More realistic modelling can beachieved by treating the fire asa fluid in motion.

• Flames are incandescentgasses in motion

• Fluid motion is described by adifferential equation namedthe Navier-Stokes Equation

• Numerical solutions can beused to find a velocity field

• Particles move at thevelocities defined in the field


Ocean Waves

Another fluid modellingproblem is how to createocean waves.

Surface tension and driv-ing forces need to bemodelled.

A current research prob-lem is how to make thembreak


In Summary

• Computers have been a major force in film makingfor forty years.

• Computer Scientists contribute to the industry inmany ways:

• Analysis of 3D geometry• Specialised Hardware Design (GPU)• Describing and constraining behaviour• &c

• The challenges to computer scientists are:• Achieving Visual Realism• Creating Natural Movements for Avatars• Modelling and Rendering Amorphous Objects

• There are many small hi-tech companies in the fieldwanting excellent computer science graduates.


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