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.
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.
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