1st Edition

Physics for Animators

By Michele Bousquet Copyright 2016
    356 Pages
    by CRC Press

    356 Pages
    by CRC Press

    Achieving believable motion in animation requires an understanding of physics that most of us missed out on in art school. Although animators often break the laws of physics for comedic or dramatic effect, you need to know which laws you’re breaking in order to make it work. And while large studios might be able to spend a lot of time and money testing different approaches or hiring a physics consultant, smaller studios and independent animators have no such luxury. This book takes the mystery out of physics tasks like character motion, light and shadow placement, explosions, ocean movement, and outer space scenes, making it easy to apply realistic physics to your work.

    • Physics concepts are explained in animator’s terms, relating concepts specifically to animation movement and appearance.
    • Complex mathematical concepts are broken down into clear steps you can follow to solve animation problems quickly and effectively.
    • Bonus companion website at www.physicsforanimators.com offers additional resources, including examples in movies and games, links to resources, and tips on using physics in your work.

    Uniting theory and practice, author Michele Bousquet teaches animators how to swiftly and efficiently create scientifically accurate scenes and fix problem spots, and how and when to break the laws of physics. Ideal for everything from classical 2D animation to advanced CG special effects, this book provides animators with solutions that are simple, quick, and powerful.

    ACKNOWLEDGEMENT

    FOREWORD

    INTRODUCTION

    SECTION I: CLASSICAL PHYSICS

    CHAPTER 1: MATTER AND MASSES

    Matter

    Composition of Matter

    Atoms and Binding

    Nuclear Fusion

    Masses

    Mass vs. Weight

    Center of Mass

    CHAPTER 2: MOTION AND TIMING

    Motion Lines and Paths

    Linear Motion

    Circular Motion

    Types of Circular Motion

    Rotational Motion

    Rotation and Distance

    Calculating the Number of Times a Wheel Turns

    Spinning, Tumbling, and Wobbling

    Centripetal Motion

    When Centripetal Force Stops

    Circular Speed

    Centrifugal Force

    Centripetal Force and Vehicles

    Pendulum Motion

    Wave Motion

    What Waves Do

    Visibility of Waves

    Types of Waves

    Transverse Waves

    Longitudinal Waves

    Wave Properties

    Amplitude

    Wavelength

    Frequency

    Wave Velocity

    Wave Relations

    Wave Phase

    Wave Addition and Cancellation

    Standing Waves

    Common Sound Effects

    Resonance

    Doppler Effect

    Sonic Boom

    Timing

    Timing Tools

    Uniform Motion Timing

    Slow In and Slow Out

    Acceleration Timing

    Constant Forces

    Forces Exerted by Characters

    Constant Force and Acceleration

    The Odd Rule

    Odd Rule Multipliers

    Odd Rule Scenarios

    Motion Graphs

    Constant Speed

    Acceleration

    Acceleration of Gravity

    Swinging

    CHAPTER 3: FORCES

    Components of Force

    Familiar and Unfamiliar Forces

    Familiar, Non-Random Forces

    Unfamiliar Forces

    Variable Forces

    Gravity

    Gravitational Acceleration

    Common Misconceptions about Gravity

    Timing for Gravity

    Calculating Total Time and Distance

    Physics-Based Calculations

    Visual Calculation Methods

    The Odd Rule

    Fourth Down at Half Time

    Falling a la Chai

    Moving and Falling

    Ascending Against Gravity

    Projectile Velocity

    Center of Gravity

    Line of Gravity

    Tipping and Center of Gravity

    Lowering and Raising the CG

    Friction

    Static and Kinetic Friction

    Friction on Flat Surfaces

    Frictionless Surfaces

    Coefficient of Friction

    Effects of Friction

    Pressure and Gases

    Pressure Increase from Heat

    Heated Gas in a Container

    Heated Air in Atmosphere

    Chemical Reaction

    Force from Pressure Decrease

    Atmospheric Pressure

    Air Resistance

    Aerodynamic Lift

    Pressure Differences in Action

    Torque

    Torque Basics

    Torque Terminology

    Maximizing Torque

    Visualizing Torque

    Calculating Torque

    Lever Systems

    Efficiency vs. Speed

    Neutral Efficiency

    Lever System Classes

    First Class Systems

    Second Class Levers

    Third Class Levers

    Balancing Torque in a Lever System

    Increasing Leverage

    Torque in Animation

    Rotational Inertia

    Action / Reaction

    Action/Reaction and Balanced Forces

    Action/Reaction with Two Mobile Objects

    Action/Reaction and Weight

    Action/Reaction and Fixed Objects

    Electricity and Magnetism

    Electricity

    Electrical Charge

    Static Electricity

    Flowing Electricity

    Conductors vs. Insulators

    Electric Current

    Electric Shock

    Sparks and Lightning

    Magnetism

    Magnetic Fields

    Making a Magnet

    Electromagnets

    Demagnetization

    Visualizing Electricity and Magnetism

    Electric Shock

    Electric Current

    Magnetism

    EMPs

    CHAPTER 4: LIGHT AND COLOR

    Light Basics

    Light as Rays

    Light and Reflection

    Seeing in a Mirror

    Bouncing Light Rays

    Attenuation

    Physically Based Lights

    Shadows

    Cast Shadows

    Umbra and Penumbra

    Sharp and Fuzzy Shadows

    Shadow Angle

    Light Source Shapes

    Shadow Intensity

    Form and Occlusion Shadows

    Reflection

    Specular Reflection

    Diffuse Reflection

    Diffuse Reflection and Light Intensity

    Detecting Shape and Color

    Diffuse vs. Specular Reflections

    Diffuse Interreflection

    Partial Reflections

    Refraction

    Caustics

    Gamma Correction

    Linear vs. Curved Light Intensity

    Gamma Correction for Real World Perception

    Gamma Correction and Cameras

    Gamma Correction on Digital Files

    Gamma Calculations

    Monitor Gamma Adjustment

    RGB Gamma Curves

    Linear Workflow

    Section II Character Design and Animation

    CHAPTER 5: CHARACTER DESIGN

    Size and Scale

    Proportion and Scale

    Weight and Strength

    Physical Characteristics and Size

    Posture

    Deformability

    Wing Size and Shape

    Climate

    Longevity

    Sound

    Babyness

    Joints

    Types of Joints

    Animal Joints

    Joints as Levers

    Elbow

    Foot

    Neck

    Muscles for Joints

    Weight Distribution

    Character Center of Gravity

    Balance

    Improving Balance

    CHAPTER 6: CHARACTER ANIMATION

    Jumping

    Parts of a Jump

    Calculating Jump Actions

    Calculating Jump Timing

    Jump Magnification

    Jump Magnification and Acceleration

    Push Time

    Push Key Spacing

    Motion Arc and Jump Timing

    Landing

    Stop Time

    Very High Jumps

    Walking

    Poses

    Strides and Steps

    Walk Timing

    Walking and Energy Efficiency

    Horizontal CG Shift

    Vertical CG Shift

    Hip Rotation

    Shoulder Rotation

    Dancing and Gymnastics

    Torque and Turning

    Balance with Multiple Characters

    Gymnastics Lever Systems

    Lifting Weight

    Shifting Body Weight

    Sitting and Standing

    Getting Hit

    Fight Scenes

    Momentum and Force of Impact

    Changing Momentum

    Force and Changing Momentum

    Action/Reaction and Changing Momentum

    Recoil

    Tipping Over

    Rotational Inertia and Tipping

    Tipping and Friction

    Drag and Follow Through

    Drag

    Follow Through

    Overlapping Action

    Length and Motion

    Surface Area and Motion

    SECTION III: VISUAL EFFECTS

    CHAPTER 7: ENVIRONMENT

    Clouds

    What’s in a Cloud

    Types of Clouds

    Cloud Altitudes

    Inside a Cloud

    Movement of Clouds

    Cloud Effects

    Cloud Combinations

    God Rays

    Backlit Clouds

    Rain

    Rain Formation

    Types of Rain Clouds

    More about Rain Clouds

    Wind and Rain

    Where Rain Forms

    Predicting Rain

    Weather from the West

    Raindrops

    Falling Raindrops

    Invisible Raindrops: Puddle Effects

    Slow-Moving Raindrops: Windowpane

    Lightning

    How Lightning Forms

    Cloud-to-Cloud Lightning

    Lightning Formation and Appearance

    Effects from Lightning

    Thunder

    CHAPTER 8: FIRE AND EXPLOSIONS

    Fire

    Flames

    Flame Appearance

    Creating Flames

    Smoldering Solid Matter

    Fireball

    Mushroom Clouds

    Mushroom Clouds in Animation

    Smoke

    Smoke Appearance

    Puffy Smoke

    Tendril Smoke

    Campfire Smoke

    Explosions

    Types of Explosions

    Life of an Explosion

    Before the Explosion

    After the Explosion

    Role of Containers

    Timing for Explosions

    Shockwaves

    Shockwaves Through Air

    Shockwaves Through the Ground

    Breakage and Fracture

    Anatomy of Fracture

    Crack Patterns

    Inherent Weak Points

    Internal Cracks

    Animating Breakage

    How Physics Engines Determine Fracture

    Flying Pieces

    CHAPTER 9: FLUID EFFECTS

    Properties of Liquids

    Cohesion

    Adhesion

    Viscosity

    Newtonian and Non-Newtonian Fluids

    Solid/Liquid Behavior of Non-Newtonian Fluids

    Surface Tension

    Buoyancy

    Liquid Appearance

    Meniscus

    Pouring Shapes

    Oceans and Lakes

    Waves

    Wave Terminology

    How Ocean Waves Form

    Movement of Waves

    Breaking Waves

    Floating on a Wave

    Ocean and Lake Appearance

    Water Reflection

    Color of the Ocean

    Spray, Mist, and Foam

    Shadows on Water

    CHAPTER 10: EARTH AND OUTER SPACE

    Earth Today

    Earth’s Layers

    Atmosphere

    Atmospheric Levels

    Height of Vehicles in Atmosphere

    Formation of Earth

    Gaseous Earth

    Supercontinents

    Formation of Modern Landscape

    Tectonic Shifts

    Volcanism

    Bombardment

    Erosion

    Glaciers

    Earth’s Crust

    What’s a Rock?

    How Rock Forms

    Rock Composition

    Rock Classification

    Causes of Geology

    Geology from Magma

    Geology from Compression

    Geology from Heat and Pressure

    Geology from Buoyancy

    Geology from Weathering and Erosion

    Designing a Landscape

    Usual Rock Colors

    Unusual Rock Colors

    Life on Earth

    Fossils

    Meteorites and Life on Earth

    Evolution and Diversity

    Outer Space

    Origin of the Universe

    Stars

    Galaxies

    Properties of Galaxies

    Nebulas

    The Vacuum of Outer Space

    Temperature in a Vacuum

    Sound in a Vacuum

    Radiation

    Biography

    Michele Bousquet is a longtime animator and instructor, and the author of more than 20 books on computer animation. Her freelance animation work has served clients like Autodesk and the Australian Broadcasting Corporation, and she has taught university-level animation classes at countless locations, including several art institutes. After years of answering questions about physics from animation students, Michele took on the task of formulating the answers into this book. Michele holds a Bachelor’s degree in Mathematics and Computer Science from McGill University.