CS99k: Sophomore Dialog on "Digital Actors"
2000 Spring Quarter
Digital actors are an emerging field of study, with applications
to video games, movies, simulation and training, manufacturing,
animated web pages, etc. This course will introduce this new field
and will present a number of computational techniques
to create and animate digital actors on computer displays.
These techniques range from robotics (kinematics, dynamics,
motion control), to geometric computing (geometric modeling,
collision detection, motion planning), to computer vision (motion
capture), to graphics (visibility computation, rendering). The
course will start by considering the general problem of
creating/animating digital actors and will then break this problem
into smaller technical subproblems (e.g., kinematic modeling
of digital actors, simulation of visual and touch sensing,
generation of group behavior, software architecture).
Each meeting will study one subproblem using a representative
paper published on this problem. The course will be
illustrated with existing software. Each student will have to
read a subset of the papers and to comment creatively on them.
Course organization and Assignments
The course will consist of eight two-hour meetings in the Spring'00,
on Mondays, from 3 to 5pm, in Gates 100.
The first two meetings will introduce the course, give an overview of
the material that will be covered in the other meetings, and
illustrate the concept of a digital actor with one of the most
comprehensive software systems commercially available to create and
animate digital actors. They will also describe techniques to
represent motion in a computer.
Each other meeting will focus on a limited topic. In general, I will
give a brief introduction of the topic; then three students will
present technical papers (or book chapters) related to this topic
(20-minute presentation). The rest of the time will be used for
discussion. Occasionally, there will be a guest speaker.
Each student will have to do the following work:
- Attend every meeting.
- Prepare and give two presentations.
- Read the papers marked with *** prior to each class, in order to
participate in the discussions (the marking of these papers is in
- Do a final homework (2 hours), which will consist of answering a
series of questions related to issues addressed during the class meetings.
Students and Emails
Patricia (Sha Sha) Chu, shasha1@leland
Robert Frezza, bfrezza@leland
Kawon Lee, firstname.lastname@example.org
Chris Montgomery, cmonty@leland
Shane Witnov, email@example.com
Schedule and Syllabus
Meeting 1 (April 3) : Notion of a Digital Actor and Motion Representation
- Topics: Class-notes.ppt
- Relation to graphic animation
- Autonomous virtual character, task-level animation
- Applications: videogames, movies, ergonomics, training, webpage
animation, animation of slide shows
- Real-time (interactive) vs. off-line animation
- Geometry, kinematics, and dynamics of actor
- Sensing and cognitive model of actor
- Motion control
- High-level and group behaviors
- Animation of soft tissue: clothes, skin
- Motion representation and generation : degree of freedom; configuration space;
parametrization of degrees of freedom; path in configuration space;
trajectory in configurationXtime space; key regions in configuration space:
obstacles, visibility, stability; homotopic paths.
Meeting 2 (April 10) : Example of Digital Actor Authoring Software: Motivate
- Guest speaker: Yotto Koga (The Motion Factory)
- Software demo:
The Motivate system of The Motion
Factory, by Yotto Koga.
- ***N.I. Badler, R. Bindiganavale, J. Bourne, J. Allbeck, J. Shi,
and M. Palmer. Real Time
Virtual Humans, International Conference on Digital Media
Futures, Bradford, UK, April 1999.
- ***J.C. Latombe. Robot Motion Planning, Kluwer Academic,
1991. Chapter 2. Configuration Space of a Rigid Object,
- J.C. Latombe. Robot Motion Planning, Kluwer Academic,
1991. Chapter 3. Obstacles in Configuration Space, pages
Meeting 3 (April 17) : Modeling (Geometry, Kinematics, Dynamics) a Digital Actor
- Geometric, kinematic, and dynamic description
- Forward and inverse kinematics
- Forward and inverse dynamics
- Modeling of human body
- Animation of human athletes
- Video of Jessica Hodgins on Human Atheletes
- J.J. Craig. Introduction to Robotics. Addison
- N.I. Badler, C.B. Phillips, and
B.L. Webber. Chapter 2 -- Body Modeling of Simulating
Humans: Computer Graphics, Animation, and Control, Oxford
University Press, 1993.
- ***B. Roehl. Specification for a
Standard VRML Humanoid, 1997
- Zhao and N. Badler.
Inverse kinematics positioning using nonlinear programming for
highly articulated figures, ACM Transactions on Graphics,
13(4), pp. 313-336, Oct. 1994.
- ***J. Hodgins and W. Wooten. Animating
Human Athletes. In Robotics Research (eds. Y. Shirai and
S. Hirose), Springer, pp. 356-367, 1998
Students: Patricia (Sha Sha) Chu, Robert Frezza, Arjun Rihan, Shane Witnov
- Human body modeling (papers by Badler,
Phillips, and Webber, and by Roehl)
- Kinematic representation
- Inverse kinematics (paper by Zhao and Badler)
- Animating athletes (paper by Hodgins and Wooten) slides.ppt
Meeting 4 (April 24) : Motion Generation Techniques
- Principles of Traditional Animation
- Keyframe interpolation
- Motion capture
- Motion planning
- Motion control
- Guest Speaker: Chris Bregler, on motion capture.
- Video: Bregler's video on 3D visual tracking and motion capture.
Students: Shane Witnov
- Keyframe interpolation (chapter by Parent)
- Retargetting motion to new characters (paper by
Meeting 5 (May 1) : Motion Planning
- Probabilistic roadmaps for path planning with many degrees of freedom
- Collision checking and distance computation
- Kinodynamic motion planning
- Manipulation planning
- Motion planning in dynamic environments
- Motion planing videos
- Guest Speaker Craig Reynolds (Sony), on animating crowds and
These are relevant webpages for his presentations:
Interaction with Groups of Autonomous Characters (pdf file)
- ***L.E. Kavraki, P. Svestka, J.C. Latombe, and M. Overmars.
Roadmaps for Path Planning in High-Dimensional Configuration Spaces.
IEEE Transactions on Robotics and Automation, 12(4):566-580, 1996.
- M. Lin et al. Interactive and Exact
Collision Detection for Virtual and Simulated Environments.
- J. Kuffner and S. LaValle. Randomized
Kinodynamic Planning, IEEE Int. Conf. on Robotics and
Automation, Detroit, MI, May 10-15, 1999.
- Y. Koga, K. Kondo, J. Kuffner, and J.C. Latombe.
Motions with Intentions.
Proc. SIGGRAPH'94, pp. 395-408, 1995.
Students: Chris Montgomery
- Randomized motion planning (Kavraki et al. paper) slides.ppt
- Collision detection (Lin et al. website)
- "Planning motions with intentions" paper
Meeting 6 (May 8) : Digital Actors with Sensing and Memory
- Simulating sensing
- Visibility analysis
- Map building
- Actor localization
- Memory models
- James Kuffner's autonomous actors
- Guest Speaker Oussama Khatib, on animating a humanoid.
- ***J.J. Kuffner and J.C. Latombe. Fast
Synthetic Vision, Memory, and Learning Models for Virtual
Humans. IEEE Int. Conf. on Computer Animation,
Geneva, Switzerland. May 26-29, 1999.
- H. Noser and D. Thalmann. Sensor Based
Synthetic Actors in a Tennis Game Simulation. The Visual
Computer, Vol.14, No.4, pp.193-205, 1998.
- D. Terzopoulos and T. Rabie. Animat Vision:
Active vision in artificial animals. Videre: Journal of
Computer Vision Research, 1(1), pp. 2-19, September, 1997.
Students: Patricia (Sha Sha) Chu, Robert Frezza, Kawon Lee
Meeting 7 (May 15) : Animating Deformable Objects and Soft Tissues
- Soft tissue modeling
- Spacetime constraints
- Cloth animation
- Facial animation
- Hair animation
- Guest Speakers: Joel Brown and Stephen Sorkin, on soft-tissue modeling and
collision detection, respectively.
- Software demo:
- Joel Brown's elastic mesh
- Stephen Sorkin's collsion detector
- Y. Lee, D. Terzopoulos, and K. Waters. Realistic Modeling for
Facial Animation. Proc. SIGGRAPH'95, pp. 55-62, 1995.
- ***Facial Animation.
- D. Baraff and A. Witkin. Large Steps in
Cloth Animation. Proc. SIGGRAPH'98, pp. 43-54, 1998.
- Sumner, R. W., O'Brien, J. F., Hodgins, J. K., 1999. Animating
Sand, Mud, and Snow. Computer Graphics Forum, January
1999, Vol. 18, No. 1.
Students: Kawon Lee, Chris Montgomery, John Rector
- Facial animation
- Cloth animation (Baraff and Witkin paper)
Meeting 8 (May 22): High-Level Behaviors and Man-Machine Interaction
- Target tracking, searching for an object
- Group behaviors: small groups, crowds, flocks
- Particle/potential field techniques
- Agents, task planning, learning
- Interaction with digital actors
- Haptic control of motion
- Software demos:
- Carlo Guestrin's soccer playing robots
- Diego Ruspini's haptic interface
- Website: SensAble
- D. Ruspini, K. Kolarov, and O. Khatib. The
Haptic Display of Complex Graphical Environments.
Proc. SIGGRAPH'97, pp. 345-352, 1997.
- H.H. Gonzalez-Banos, L.J. Guibas, J.C. Latombe, S.M. LaValle,
D. Lin, R. Motwani, and C. Tomasi. Motion
Planning with Visibility Constraints: Building Autonomous
Observers. In Robotics Research - The Eighth International
Symposium, Y. Shirai and S. Hirose (eds.) Springer,
pp. 95-101, 1998.
- C. Guestrin.
Motion Planning for Soccer Playing Robots.
- ***G. Sannier, S. Balsicoy, N. Magnenat-Thalmann, D. Thalmann. An Interactive Interface for Directing Virtual
Humans. Proc. ISCIS'98, IOS Press, 1998
- B. Blumberg and T. Galyean. Multi-level Direction of Autonomous Creatures
for Real-Time Virtual Environments. Proc. SIGGRAPH'95,
Students: John Rector, Arjun Rihan
- Haptic interaction
- Motion planning with visibility constraints
(Gonzalez et al.'s paper )
- Directing virtual humans (Sannier et al.'s paper)
Links to relevant research:
Links to relevant companies: