Matchmoving E-Book

Tim Dobbert

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 506

Veröffentlichungsjahr: 2012

Beschreibung

Get your foot in the studio door by learning the art of matchmoving Matchmoving is a technique that allows computer graphics to be inserted into live-action footage with correct position, scale, orientation, and motion. Also known as motion tracking, it's what allows movie monsters to run down Main Street and robots to run through crowds--and look real. Now this unique book from a top expert from Industrial Light and Magic teaches you the art of matchmoving. With step-by-step tutorials and pages of examples, this book first explains the basics and then shows you professional techniques, from 3D calibration and tracking, to stereoscopy, and more. * Explains concepts and teaches professional techniques for successful matchmoving * Authored by a top matchmove specialist from Industrial Light and Magic, who walks you through step-by-step tutorials and impressive examples * Covers matchmoving basics, 2D tracking, 3D calibration and tracking, automatic tracking, cameras, integrating matchmoves, and stereoscopy Learn how studio visual effects professionals make all the right matchmoves with Matchmoving: The Invisible Art of Camera Tracking 2nd Edition.

Leseprobe

Table of Contents

Acknowledgments

About the Author

Introduction

Chapter 1: The Basics of Matchmoving

Exploring a Typical Matchmove

Moving from 3D to 2D and Back Again

Understanding the Matchmoving Process

Matchmoving in the Production Pipeline

Perspective Matching Tutorial

Evaluating and Adjusting the Camera

Moving Toward Moving Pictures

Chapter 2: Matchmoving Software

Using Matchmoving Programs

Introducing Photogrammetry

Understanding How Matchmoving Programs Work

Laying Down Your First Tracks

Chapter 3: 2D Tracking

Understanding the 2D Tracking Process

Exploring the Anatomy of a 2D Track

Track Placement: Making Every Track Count

Getting Tracks to Stick

Following Hints for Effective 2D Tracking

Handling Plate Issues

Optimizing the Plate for 2D Tracking

2D Tracking Tutorial

Moving from 2D to 3D

Chapter 4: 3D Calibration

Understanding “Good” Calibration

Calibrating Your Cameras

Evaluating the Solution

Determining Camera Moves

Setting Up a Coordinate System

Coordinate System Tutorial

But It Gets Better

Chapter 5: Automatic Tracking

Tracking on Autopilot

Editing Automatic Tracks

Using Masks

Reaping the Benefits of Automatic Tracking

Implementing the Automatic Tracking Process

Ready for a Brief Detour

Chapter 6: Cameras

How Film Cameras Work

Lenses

Film Backs

Format

Lens Distortion

Capture and Digitization

Keeping It All Straight

Fitting In

Chapter 7: Set Fitting

Fitting the Camera

Checking the Matchmove

Fitting the Set

Set-Fitting Tutorial

Altering the Coordinate System

Delivering the Scene

And Now on to the Real World … Sort Of

Chapter 8: Being on Set

Getting the Right Information

Getting Camera Information

Marking Up the Set

Working with Others on Set

Building a Matchmoving Kit

Shooting Distortion Grids

Filling In the Details

Chapter 9: Matchamation

Understanding the Basic Technique

Making Model Changes

Working with Imperfect Data

Matchamation Tutorial

When the Going Gets Tough

Chapter 10: Troubleshooting and Advanced Techniques

Performing Effective Troubleshooting

Following a Troubleshooting Checklist

Diagnosing the Problem

Using Advanced Tools and Tricks

Tracking Moving Objects

Chapter 11: Object Tracking

The Object-Tracking Process

Object-Tracking Tutorial

Common Problems with Object Tracking

Geometry Tracking

Geometry-Tracking Tutorial

Common Problems with Geometry Tracking

Advanced Object Tracking

And That’s Not All

Chapter 12: Multipurposing Matchmoving Data

Creating Special Cameras

Matchmoves for Paint Work: “Patchmoves”

Matchmoves for Compositors

Matchmoves for TD Work

Not the End of the Road

Chapter 13: Stereo

Understanding Stereoscopy

Filming Stereo Footage

Viewing Stereo Footage

Matchmoving Stereo Footage

Overcoming Common Problems

So What’s Next?

Appendix A: Resources

Appendix B: Matchmoving Software and Useful Links

Matchmoving Software

Other Useful Programs

Books

Websites

Appendix C: Film Formats

16 mm Formats

35 mm Formats

Large Formats

Digital Formats

Calculating the Film Back for Cropped Images

Glossary

Index

Gallery

Acquisitions Editor: Mariann Barsolo

Development Editor: Sara Barry

Technical Editor: Michael Raphaelovich

Production Editor: Eric Charbonneau

Copy Editor: Sharon Wilkey

Editorial Manager: Pete Gaughan

Production Manager: Tim Tate

Vice President and Executive Group Publisher: Richard Swadley

Vice President and Publisher: Neil Edde

Book Designer: Franz Baumhackl

Compositors: Cody Gates and Kate Kaminski, Happenstance Type-O-Rama

Proofreader: Rebecca Rider

Indexer: Ted Laux

Project Coordinator, Cover: Katherine Crocker

Cover Designer: Ryan Sneed

Cover Image: © Tim Dobbert

Copyright © 2013 by John Wiley & Sons, Inc., Indianapolis, Indiana

Published simultaneously in Canada

ISBN: 978-1-118-35205-2

ISBN: 978-1-118-46123-5 (ebk.)

ISBN: 978-1-118-52966-9 (ebk.)

ISBN: 978-1-118-52927-0 (ebk.)

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Dear Reader,

Thank you for choosing Matchmoving: The Invisible Art of Camera Tracking, Second Edition.This book is part of a family of premium-quality Sybex books, all of which are written by outstanding authors who combine practical experience with a gift for teaching.

Sybex was founded in 1976. More than 30 years later, we’re still committed to producing consistently exceptional books. With each of our titles, we’re working hard to set a new standard for the industry. From the paper we print on to the authors we work with, our goal is to bring you the best books available.

I hope you see all that reflected in these pages. I’d be very interested to hear your comments and get your feedback on how we’re doing. Feel free to let me know what you think about this or any other Sybex book by sending me an email at [email protected]. If you think you’ve found a technical error in this book, please visit http://sybex.custhelp.com. Customer feedback is critical to our efforts at Sybex.

Best regards,

Neil Edde

Vice President and Publisher

Sybex, an Imprint of Wiley

For Desiree, without whom this book would not have been possible.

Acknowledgments

I’d like to send out a thanks to everyone at Sybex who was involved with this book, especially Mariann Barsolo, Pete Gaughan, Sara Barry, Eric Charbonneau, Michael Raphaelovich, Sharon Wilkey, Cody Gates, and Kate Kaminski. You helped bring focus to my ideas, and your encouragement was greatly appreciated.

I’d like to thank Sean Wagstaff for his early support and for kicking me in the pants a little to help get this book off the ground. Thanks to the folks at Andersson Technologies and The Pixel Farm, especially Russ Andersson and Daryl Shail for their support. Thanks also to Jeff Saltzman, Joe Stevenson, and Brian Cantwell at Industrial Light & Magic for all of their feedback and suggestions, as well as Jesse Kim and the Academy of Art University Spring ’12 matchmoving class and Tony Rizo for their help with the Second Edition content.

I’d particularly like to thank everyone who contributed some of the fantastic images and sequences used in this book: Greg Downing, Alex Lindsay at Pixel Corps, Jorge Mendoza of Litigation Animation, Quan Tran, and Trevor Tuttle.

And special thanks to my wife, Desiree, whose patience and support never flagged for a moment during the writing of both editions of this book. I can’t express how much I appreciate everything you’ve done. And special thanks too, to my daughters, Sabina and Alex, who gave up a lot of their “daddy-time” so that this book could happen.

About the Author

Tim Dobbert has been working in the visual effects industry for more than 10 years. He began as an animator/generalist at Flat Earth Productions and Foundation Imaging, working on projects such as Roughnecks: Starship Troopers Chronicles and Max Steel.

In 2000, he began working as a CG artist for Realviz, the company that created MatchMover Pro software. In this capacity, in addition to gaining a deeper knowledge of how matchmoving programs work, he traveled throughout the world helping companies establish their matchmoving pipelines and training them on the software. During this time, he created the first matchmoving classes at the Academy of Art University in San Francisco (and continued to teach them for another 10 years afterward).

In 2004, he created the matchmoving department at an up-and-coming visual effects studio known as The Orphanage. Over the next four years at that company, he worked on such films as Hellboy, Sky Captain and the World of Tomorrow, Harry Potter and the Goblet of Fire, Pirates of the Caribbean: Dead Man’s Chest, Sin City, and Iron Man. While there, he wrote the first edition of this book, which was the first book ever written exclusively on the subject of matchmoving.

In 2009, he joined Industrial Light & Magic, where he has worked on films such as Avatar and Pirates of the Caribbean: On Stranger Tides.

Introduction

I remember getting my first glimpses of the sequences in Hellboy that my team of matchmovers was about to work on. One that stood out in particular was the opening sequence, in which the villains were attempting to open the gates of hell with a special machine. The sequence had all the elements of a great action film: a driving rainstorm, lightning, explosions, people running everywhere, and a lot of fast-moving camera work. I realized immediately that this would be an incredible sequence, but also a very difficult one from the vantage point of a matchmover.

Experienced matchmovers look at effects shots with a different eye than other visual effects artists because their job is unique. Their main goal is to decipher the clues in the live-action footage and create a 3D scene that animators can use to place their effects in the shot. It is an important job, even though it is not readily visible in the final shot. Actually, the only time a matchmove is visible in the shot is if it is a bad matchmove. I often tell my students, “If you’ve done your job right, no one should ever know you’ve done your job at all.”

In a lot of ways, matchmoving, or camera tracking as it’s sometimes called, is really just like solving a puzzle. Sometimes the puzzle can be fairly straightforward, and other times it can be extremely difficult. But it is this problem-solving aspect of matchmoving that has kept me working in this specialized area of visual effects for so long.

Many visual effects artists understand the need for matchmoving, but very few know what’s really happening “under the hood,” and that is part of the reason for this book. There is a strong technical aspect to matchmoving, but there is an art to getting a tough matchmove to work. The art of matchmoving becomes easier the more you do it, but interesting technical challenges always remain around every corner.

Who Should Read This Book

I’ve written this book for two groups of people: visual effects artists and students.

Visual effects artists who are not matchmovers by trade are occasionally tasked with matchmoving in addition to their other duties as animators or technical directors. Generally, these folks are given some matchmoving software and a few tutorials and sent off to matchmove the shot. Being highly talented visual effects artists, they quickly figure out how the software works and throw their shot at it. If they’re lucky, it’s an easy shot, and they achieve satisfactory results. But often they find that their footage is considerably more difficult than the tutorial footage and they are able to arrive at a solution only through a lengthy trial-and-error process. Much of the pain of matchmoving can be eliminated by knowing how the matchmoving software achieves its results. Relatively simple techniques can speed up the process, eliminate the guesswork, and help the matchmover deliver a quality solution to artists further down the production pipeline.

The second type of person is the 3D animation or compositing student. There are the obvious benefits to knowing how to accurately track 3D elements into your footage, but there are other more compelling reasons to master these skills. I firmly believe that matchmoving is a great way to break into the visual effects industry. This industry is a highly competitive one, and with little or no production experience, many students must bang their heads tirelessly on the doors of studios in search of a first job.

Many of my own students have landed their first jobs in the matchmoving departments of high-profile visual effects companies. There is one simple reason for this: most visual effects artists don’t want to be matchmovers! They’d much rather be character animators, effects technical directors, or compositors. And who can blame them? It’s nice to be able to point to a cool character or explosion and say, “I did that!” But no one ever says, “Did you notice the brilliant matchmoves on that show? I didn’t see one single slip.” Matchmoving may not be the most glamorous job in visual effects, but there will always be a strong demand for knowledgeable matchmovers.

I’ve written this book to give visual effects artists the tools and techniques to help make their encounters with matchmoving as easy and pain-free and possible. And if you’re one of the few who decide to make a career of matchmoving, this book will be a great starting point for your studies. This book won’t tell you what every button and menu does for each matchmoving program—I’ll leave that to the user guides. It will, however, show you how those programs work and even walk you through the process.

I’ve designed this book to be as non-program-specific as possible, apart from the obvious need for matchmove-specific software. It was really tough to decide which matchmoving programs to use for the tutorials, because there are so many great options for matchmovers these days. Because space was limited, I decided to pare it down to Andersson Technologies’ SynthEyes, The Pixel Farm’s PFTrack, and Vicon’s boujou. But for the most part, the techniques I describe here are compatible with all 3D animation and matchmoving software packages and do not require special knowledge of any particular programs.

What’s New in the Second Edition

When I wrote the first edition of this book, I had some nagging doubts as to whether the book would be useful to folks interested in matchmoving, or whether there would even be an audience for such a book. In the seven years since, I have been fortunate enough to meet many of my readers and have received dozens of emails from all over the world, and the feedback I’ve received has been overwhelmingly positive.

In recent years, the matchmoving landscape has changed quite a bit and so, when I was asked to do a second edition, I was excited to be able to get the book back up-to-date. In this edition, I’ve taken the feedback and questions I’ve received over the years, and used them to expand the content and concepts covered in the book in a number of ways. I’ve tweaked the tutorials and updated them to current software and added a lot of new material.

Matchmoving programs such as SynthEyes and PFTrack that were relative newcomers during the writing of the first edition have become the program of choice at many facilities. So in the second edition, I’ve included them in many of the tutorials.

Perhaps the most prominent change is that I’ve added two completely new chapters. Object tracking, which garnered only a brief mention in the first edition, now has its own chapter that allows you to examine this complex subject in detail. I’ve also devoted an entire chapter to one of the newest phenomena to affect matchmovers—stereo.

What’s Inside

Matchmoving: The Invisible Art of Camera Tracking is divided into 13 chapters:

Chapter 1, “The Basics of Matchmoving” A basic overview of what matchmoving is and how it fits into a typical visual effects pipeline. There’s also a tutorial for matching the perspective of a still image.

Chapter 2, “Matchmoving Software” Chapters 2 through 5 all deal with matchmoving programs and how they work. This chapter lays the groundwork by explaining the processes used in photogrammetry and how they are implemented in these programs.

Chapter 3, “2D Tracking” As one of the first steps in a matchmove, 2D tracking can make or break a solution. This chapter breaks down 2D tracking and shows ways to make yourself a more effective tracker.

Chapter 4, “3D Calibration” Calibrating, or solving, can be one of the more frustrating parts of getting a good matchmove. In this chapter, I shed light on this sometimes mysterious process and provide ways to help get the best solution possible.

Chapter 5, “Automatic Tracking” Most matchmoving programs these days have automatic 2D tracking capabilities. In this chapter, I show how automatic tracking is used and how it differs from other forms of 2D tracking.

Chapter 6, “Cameras” This is a chapter entirely devoted to real-world cameras, because that is a primary concern for matchmovers. It covers everything about cameras that is important to a matchmover, including how cameras are similar or different from their virtual counterparts in animation programs.

Chapter 7, “Set Fitting” Getting the right camera is only half the battle with a typical matchmove, because you still must fit the camera into any existing scenes you may have. This chapter shows you how to quickly and accurately place your cameras into your 3D scene.

Chapter 8, “Being on Set” If you’re ever asked to prep a set for matchmoving, this is an important chapter for you to read. I cover the roles and responsibilities of a matchmover on a film shoot as well as how to get the best information possible.

Chapter 9, “Matchamation” Matchmovers sometimes have to match more than just cameras. This chapter shows you how to match CG objects to moving objects in the plate.

Chapter 10, “Troubleshooting and Advanced Techniques” This chapter covers ways to help solve difficult shots or shots that are just giving you problems. It includes a troubleshooting checklist and tips to coaxing a good solution out of mediocre data.

Chapter 11, “Object Tracking” This chapter covers the increasingly common process involved in tracking an object’s motion. It covers both regular object tracking and one of the newer tools in a matchmover’s quiver, geometry tracking.

Chapter 12, “Multipurposing Matchmoving Data” There are lots of ways to use matchmoving data besides calculating cameras. This chapter shows you some of the possibilities.

Chapter 13, “Stereo” 3D films have become the rage again, and this chapter show you how 3D films work and, more important, how to matchmove stereo footage. It includes a complete overview of the stereo process and the basic workflow of matchmoving in stereo.

I have provided some useful documents, a complete list of which you can find in Appendix A, “Resources.” I’ve also included a list of current matchmoving programs in Appendix B, “Matchmoving Software and Useful Links,” for those interested in knowing more about them. Appendix C, “Film Formats,” is a detailed reference of camera formats, including film-back measurements and special considerations necessary when tracking digital formats. Finally, matchmoving comes with its fair share of jargon, so I’ve listed key words in a glossary at the back of the book.

As more and more directors add CG elements to their projects, there will be a greater need for matchmovers. Although matchmoving is truly an invisible art, I hope that this book will help bring to light many of the techniques that have languished in anonymity for so long.

How to Contact the Author

If you’d like to contact me with feedback or questions, write to [email protected].

Chapter 1

The Basics of Matchmoving

Anytime computer-generated imagery (CGI) needs to be placed into a live-action sequence, or vice versa, a matchmove is required. But what exactly is matchmoving? Matchmoving is the process of matching CG elements into live-action footage. As a result, it’s a crucial part of many visual effects shots. Despite its importance, it is completely invisible in the final shot—that is, if it’s done right.

In this chapter, I explain the key steps of a matchmove and how matchmovers work with the rest of the visual effects team. I’ve also included a tutorial that will help you become comfortable working with cameras and perspective.

Chapter Contents

Exploring a Typical Matchmove

Moving from 3D to 2D and Back Again

Understanding the Matchmoving Process

Matchmoving in the Production Pipeline

Perspective Matching Tutorial

Exploring a Typical Matchmove

To better understand what matchmovers do, let’s consider a typical visual effects shot. Let’s say the director has called for a CG creature to crash out of a building’s window and run across the street and into an alley. Because the monster will need to interact with the window, the visual effects supervisor decides that in addition to the monster, the window-shattering effect should also be done on the computer.

On the day of shoot, the director makes artistic decisions as to how to shoot the scene and eventually decides on a camera position. There is an opening in the building where the window should be, although the panes of glass are missing. The director and the cameraman practice the camera move a few times and watch the video playback to see how it looks. When they are filming, they move the camera as though it were following the monster crashing through the window and running across the street, even though the monster isn’t there. Extras react to the imaginary beast, and props around the window are rigged with monofilament string (fishing line) to be pulled down on cue as though they were knocked over. When the director is happy with the shot, the film is sent off to be digitized and then given to the visual effects artists to add the monster.