1. Motion Capture Animation
Dr. Midori Kitagawa
Arts and Technology Program
University of Texas at Dallas
Gif animations by Dax Norman

2. What is Mocap?
Motion capture (mocap) is sampling and recording motion of humans, animals, and inanimate objects as 3D data.
The data can be used to study motion or to give an illusion of life to 3D computer models.

3. Applications Entertainment Medicine / Sports Arts / Education
Science / Engineering

4. Entertainment: Live Action Films

5. Entertainment: 3D computer animations

6. Entertainment: Video Games

7. Medicine / Sports Medicine (e.g., gait analysis, rehabilitation)
Sports (e.g. injury prevention, performance analyses, performance enhancement)

8. Arts / Education Dance and theatrical performances
Archiving (e.g., Marcel Marceau)
OSU/ACCAD

9. Science / Engineering Engineering (e.g., biped robot developments)
Computer Science (e.g., human motion database, indexing, recognitions)
Design (e.g., ergonomic product design)
Military (e.g., field exercises, virtual instructors, and role-playing games)

10. Mocap animation
Motion capture animation is different from keyframe animation in terms of how motion is created.
Same principles of animations apply to mocap animation & keyframe animation!
Combination of motion capture animation and keyframe animation is often used.

11. Keyframe animation
Keyframe is a drawing of a key moment in an animated sequence, where the motion is at its extreme.
Inbetweens fill the gaps between keyframes.
Every motion is created by animators.

12. Advantages of mocap animation
Faster to create (only if an established production pipeline exists.)
Secondary motions and all the subtle motions are captured.
-> more realism
Physical interactions between performers and props can be captured.

13. Disadvantages of mocap animation
Cost.
Manipulating mocap data is often difficult -> Re-capturing or key framing a shot with bad data is often easier.
Mapping mocap data of a performer to a 3D character with a different proportion may cause issues.

14. Popular types of mocap equipment
Magnetic systems
Mechanical systems
Optical systems

15. Magnetic systems
Utilize sensors placed on the body to measure the magnetic field generated by a transmitter source.

16. Magnetic systems  Require no special lighting condition.
 Sensors are never occluded.
X Affected by electromagnetic force.

17. Mechanical systems
Exoskeleton with angle sensors.

18. Mechanical systems  Measure joint angles (no marker ID problems).
 Sensors are never occluded.
X Breakable!
X Configuration of sensors is fixed.
X Constrains on joints.

19. Optical systems
The cameras are equipped with infrared LED's and filters.
The cameras see reflector markers.

20. Optical systems  Higher sampling rate.  Larger capture space.
X Markers are sometimes occluded -> marker ID problems.
X Provide only positional data -> joint angles need to be computed.

21. Mocap system at UTD Vicon optical system
8 high-speed MX 13 (up to 10,000 fps) and 8 high-resolution MX 40 (4 megapixels) cameras.
Capture up to 5 performers at once.

22. Mocap animation courses
Graduate level: ATEC 6352 & UG level: ATEC 4345
Group project based
Group of 3 to 5 members
Semester long project
Pre-requisite:
ATEC 3317 Modeling and texturing OR
ATEC 3327 Lighting and composition
Recommended:
ATEC 3328 Rigging I
ATEC 4337 Computer Animation

23. Mocap animation pipeline
Preproduction
Capture -> data cleaning -> retargeting
Modeling -> rigging mocap animation
Keyframe animation
Effect animation
Sound design
Texturing/lighting -> Rendering -> Composition
Post-production
* Tasks that everyone should be involved.
* Tasks that can be designated to a member or members.

24. FBX VSK MOTION BUILDER FBX FBX MB BLADE Mocap Pipeline Flow Chart MAYA
2D Image -> 2D Camera Data -> 3D Markers Positions -> Trajectories -> Recon Skeleton -> Solver Skeleton
System Calibration and Capturing and Processing Data
FBX
Circle fitting
Triangulation
Reconstruction
Skeleton with subject’s size & proportion and motion data
BLADE
Subject Calibration
VSK
VST (subject template)
MOTION
BUILDER
Capture Range of Motion (ROM)
Reconstruct trajectories of ROM
Label markers
Skeleton with subject’s size & proportion
Mocap Pipeline Flow Chart
The processes that you go through for each character
Character Setup
Correlate :
Character
&
(FBX)
Edit motion
Bake motion data to the skeleton
FBX
Character Setup
Create a skeleton
Bind skin to the skeleton
Rig the character
Skeleton with 3D character’s size & proportion (and skin)
MAYA
The processes that you repeat for each shot
Rendering
FBX
Marge the rigged character (MB) and the skeleton with motion data (FBX)
Edit motion (IK/FK blend, Trax)
Render MB
Skeleton with motion data & 3D character’s size & proportion
Maya Scene File

25. Dr. Midori Kitagawa midori@utdallas.edu ATEC 1.909