MoCap for Artists: Workflow and Techniques for Motion Capture

by Kitagawa; Midori

• ISBN13: 9780240810003
• ISBN10: 0240810007
• Edition: CD
• Format: Nonspecific Binding
• Copyright: 2008-03-24
• Publisher: Routledge

Summary

Make motion capture part of your graphics and effects arsenal. This introduction to motion capture principles and techniques delivers a working understanding of today?s state-of-the-art systems and workflows without the arcane pseudocodes and equations. Learn about the alternative systems, how they have evolved, and how they are typically used, as well as tried-and-true workflows that you can put to work for optimal effect. Demo files and tutorials provided on the companion CD deliver first-hand experience with some of the core processes. * An accessible introduction to motion capture principles and techniques that does not require a computer science background * A survey of the state-of-the-art hardware and software tools, workflows and techniques. * A CD with sample motion capture data, clips, scripts, and Maya/Motion Builder turorials.

Author Biography

Midori Kitagawa, Ph.D. is an associate professor in the Arts and Technology (ATEC) program at the University of Texas at Dallas (UTD). Dr. Kitagawa teaches 3D computer animation and motion capture and coordinates the animation curriculum in the ATEC program Brian Windsor is a mechanical engineer with the Missile and Space Intelligence Center. Formerly a graphics researcher at the Advanced Computing Center for the Arts and Design (ACCAD) at the Ohio State University, he received the Jim Henson Award for Innovation in 2007

Table of Contents

Acknowledgments	p. xi
Introduction	p. xiii
An Overview and History of Motion Capture	p. 1
About This Book	p. 1
History of Mocap	p. 2
Early attempts	p. 2
Rotoscoping	p. 4
Beginning of digital mocap	p. 6
Types of Mocap	p. 8
Optical mocap systems	p. 8
Magnetic mocap systems	p. 10
Mechanical mocap systems	p. 11
Preproduction	p. 13
Importance of Preproduction	p. 13
Pre-capture Planning	p. 13
Script	p. 14
Storyboard	p. 15
Shot list	p. 15
Animatic	p. 16
Preparation for Capture	p. 17
Talent	p. 17
Marker sets	p. 18
What are the system limitations?	p. 18
What kind of motion will be captured?	p. 19
Know the anatomy	p. 19
Capture volume	p. 21
Shot list	p. 23
Capture schedule	p. 24
Rehearsals	p. 25
Props	p. 26
Suits and markers	p. 28
Pipeline	p. 31
Setting up a Skeleton for a 3D Character	p. 31
Calibrations	p. 33
System calibration	p. 33
Subject calibration	p. 34
Capture Sessions	p. 36
Audio and video references	p. 36
Organization	p. 37
Preventing occlusions	p. 38
Cleaning Data	p. 39
Editing Data	p. 40
Applying Motions to a 3D Character	p. 43
Rendering and Post-production	p. 44
Cleaning and Editing Data	p. 47
Cleaning Marker Data	p. 47
Types of data	p. 47
Optical marker data (translational data)	p. 47
Translational and rotational data	p. 47
Skeletal data	p. 48
What to clean and what not?	p. 48
What not to clean?	p. 48
What to clean?	p. 49
Labeling/identifying	p. 49
Data cleaning methods	p. 51
Eliminating gaps	p. 51
Eliminating spikes	p. 54
Rigid body	p. 56
Filters	p. 59
When to stop?	p. 61
Applying Marker Data to the Skeleton	p. 62
Actor	p. 63
Skeleton	p. 67
Character	p. 69
Skeletal Editing	p. 73
Retargeting	p. 73
Reducing need for retargeting	p. 73
Scaling a skeleton	p. 75
Fixing foot sliding	p. 76
Working on the spine	p. 78
Blending Motions	p. 79
Selecting a blending point	p. 80
Matching positions	p. 86
Dealing with less than ideal cases	p. 86
Inverse Kinematics	p. 88
Floor Contact	p. 88
Rigid Body	p. 92
Looping Motion	p. 93
Getting motion ready	p. 93
Setting up the loop	p. 94
Walking down the z-axis	p. 94
Taking out the translation	p. 95
Poses	p. 98
Deciding what to use	p. 98
Creating a pose	p. 98
Key-framing a pose	p. 100
Data Application - Intro Level: Props	p. 103
A Stick with Two Markers	p. 103
When it fails: Occlusion	p. 103
When it fails: Rotation	p. 105
A Stick with Three Markers	p. 105
Three markers with equal distances	p. 105
Three markers on a single straight line	p. 106
Placement of three markers that works	p. 108
Flexible Objects	p. 109
Data Application - Intermediate Level: Decomposing and Composing Motions	p. 113
Mapping Multiple Motions	p. 113
Decomposing and composing upper and lower body motions	p. 113
Synchronizing upper and lower body motions	p. 116
Balance	p. 118
Breaking Motion Apart	p. 119
When you don't need all the motion	p. 119
Re-use of motion data for non-motion purposes	p. 122
Data Application - Advanced Level: Integrating Data with Character Rigs	p. 125
Mocap as Forward Kinematics Animation	p. 125
Key-frame Animation with Inverse Kinematics	p. 127
Key-framing	p. 128
IK	p. 129
Integrating Mocap Animation and Key-frame Animation	p. 130
Why do we want to do that?	p. 131
Setting up a skeleton for FK and IK	p. 131
Adding key-frame animation to mocap	p. 134
Hand Motion Capture	p. 137
Anatomy of a Hand	p. 137
Rig and Marker Set for the Hand	p. 141
Rigid hand	p. 141
Mitten	p. 143
Mitten with an independent thumb	p. 144
Mitten that stretches	p. 146
Ultimate	p. 146
Capturing Hands	p. 149
Facial Motion Capture	p. 151
Anatomy of a Face	p. 151
Camera Setup and Capture	p. 154
Facial Rig	p. 155
Facial rig with discrete joints	p. 155
Facial rig with muscles	p. 156
Facial rig with IK	p. 157
Marker Set	p. 159
Facial Data Stabilization	p. 161
Facial Data Editing	p. 164
Puppetry Capture	p. 167
Background	p. 167
Benefits	p. 168
Ideas/Inspiration	p. 169
Performance	p. 170
Projects	p. 171
Methods	p. 173
Real Time	p. 176
Mocap Data and Math	p. 179
How Data Is Created	p. 179
Optical systems	p. 179
Magnetic systems	p. 180
Mechanical systems	p. 180
Data Types and Formats	p. 181
C3D	p. 181
ASF/AMC	p. 181
BVH	p. 182
FBX	p. 183
Coordinates and Coordinate Systems	p. 183
2D and 3D coordinate systems	p. 184
Cartesian, spherical, and cylindrical coordinate systems	p. 184
Right-handed and left-handed systems	p. 185
Object space and world space	p. 186
Order of Transformation	p. 186
Euler Angle	p. 188
Gimbal Lock	p. 190
Quaternions	p. 194
Bibliography	p. 195
Shot List for Juggling Cow	p. 197
Sample Mocap Production Pipeline and Data Flow Chart	p. 199
Glossary	p. 201
Index	p. 207
Table of Contents provided by Ingram. All Rights Reserved.