CS 551/851Advanced Computer Graphics

David Brogan

General Goals

• Learn more about graphics and animation– Read and present SIGGRAPH papers

• Be aware of state of the art research

– Cover much of Parent’s animation text• Understand fundamental techniques

– Learn by doing – programming assignments

Prerequisites

• Introduction to computer graphics– Knowledge of textbook fundamentals

• OpenGL programming– Use the computer as a tool to quickly build

graphical applications

• Curiosity– Class participation is required and the

assignments will be dynamic

This course does not…

• teach how to use canned software– We won’t learn Maya or Photoshop

• require artistic skills

• focus on film making or animated cartoons– Though we occasionally turn to these fields

for insight and motivation

Let’s think about what we’ve learned already

• Virtual cameras– Transformations– Perspective

• Photorealism– Decent lighting models– Polygonal rendering

• Geometry algorithms– Line/Plane equations– Intersection computations

You’re pretty smart alreadyAmong the studies of natural causes and laws,

it is light that most delights its students. Among all the great branches of mathematics, the certainty of its demonstrations pre-eminently elevates the minds of its investigators. Perspective, therefore, should be preferred above all man’s discourses and disciplines. In this subject the visual rays are elucidated by means and demonstrations which derive their glory nor only from mathematics but also from physics; the one is adorned equally with the flowers of the other.

Leonardo da Vinci (1400’s) quoting John Pecham (1200’s)

But we labor on…• There are some who look at the things

produced by nature through glass, or other surfaces or transparent veils. They trace outlines on the surface of the transparent medium… But such an invention is to be condemned in those who do not know how to portray things without it, no how to reason about nature with their minds… They are always poor and mean in every invention and in the composition of narratives, which is the final aim of this science

Leonardo da Vinci

Advanced topics

• More realistic modeling and lighting

• Non photorealistic rendering

• Animation

• Optimization

• Perception

What do these things mean to you?

• What do you think this course should be about?

What do these things mean to you?

• Ideas from

• Video games

• Movie special effects

• Computer animated films

• Office of the future

• Video screens everywhere

• Ubiquitous computing

Topics from textbook

• Curves

• Morphing/Warping

• Kinematics/Inverse kinematics

• Physical simulation

• Particle systems

• Implicit surfaces

Topics from textbook

• Natural phenomena (plants, water, gas)

• Modeling and animating articulated characters– Facial animation– Motion capture

Topics from SIGGRAPH

• Evolving Virtual Creatures• Clouds• Spacetime Constraints• Artificial Fishes• Tour Into the Picture• Virtual Cinematographer• Virtual Reality• Others…

Other Topics

• Movie special effects– The “Making Of” movies

• Traditional film making

• Traditional animation

Potential Projects

• Build a curve editor / surface modeler

• Motion capture blending

Potential Projects

• Plant modeling

Potential Projects

• Particle system

• Physical simulation control systems

Potential Projects• Inverse kinematics of reaching arm

• Implement SIGGRAPH paper– Tour Into the Picture– Cloud Modeling

Textbooks

• Rick Parent – Computer Animation

• Frank Thomas and Ollie Johnson - Disney Animation: The Illusion of Life

• Alan Watt and Mark Watt - Advanced Animation and Rendering Techniques

• Edward Dmytryk - On Film Editing• Martin Kemp – Science of Art• Donald Bourg – Physics for Game Developers

GradingProjects 40%

Midterm 15%

Final 15%

Presentations 10%

Critiques 10%

Class Participation 10%

Perception

• Modeling perception really matters for computer animation– We can’t rely on four-hundred years of perception

research by artists– The best we have is eighty years of Disney

• In 1550, after 100 years of refining the art of perspective drawing, artists were shocked to think that the geometric purity of their modeled world didn’t map to recent discoveries of the human eye. They couldn’t even imagine how cognition affected what one “saw.” 200 more years would pass.

Perception

• Positive afterimage (persistence of vision)– the visual stimulus that remains after

illumination has changed or been removed

• Motion blur– Persistence of vision causes an object to

appear to be multiple places at once

Motion Blur

• Virtual camera in computer graphics usually shoots with infinitely small shutter speed– No motion blur results

• Without motion blur, 30 fps results in fast moving objects that look like they are strobing, or hopping– Would CG instantaneous snapshots produce

motion blur if played at 300 fps?

What’s the rate?

• Playback rate– The number of samples displayed per second

• Sample rate– The number of different images per second

Playback Rate

Sample Rate

TV Cartoon 30 6

TV Sitcom 30 30 (on fields)

CG Lipsync on film

24 12

Animation Timeline

• First Animation– 1896, Georges Melies, moving tables– 1900, J. Stuart Blackton, added smoke

• First celebrated cartoonist– Winsor McCay– Little Nemo (1911)– Gertie the Dinosaur (1914)

Animation Timeline

• 1910, Bray and Hurd– Patented translucent cels (formerly

celluloid was used, but acetate is used now) used in layers for compositing

– Patented gray-scale drawings (cool!)– Patented using pegs for registration

(alignment) of overlays– Patented the use of large background

drawings and panning camera

Bray’s Studio Produced

• Max Fleischer – Betty Boop• Paul Terry – Terrytoons• George Stallings – Tom and Jerry• Walter Lantz – Woody Woodpecker

• 1915, Fleischer patented rotoscoping– Drawing images on cells by tracing over previously

recorded live action (MoCap)

• 1920, color cartoons

Disney

• Advanced animation more than anyone else– First to have sound in 1928, Steamboat

Willie– First to use storyboards– First to attempt realism– Invented multiplane camera

Multiplane Camera

• Camera is mounted above multiple planes

• Each plane holds an animation cel

• Each plane can translate freely on 3 axes

• What is this good for?

Zooming, moving foreground characters off camera, parallax, prolonged shutter allows blurring some layers (motion blur)

Stop-motion Animation

• Willis O’Brien – King Kong

• Ray Harryhausen – Mighty Joe Young

• Nick Park – Wallace and Grommit

• Tim Burton – Nightmare Before Christmas