Project Description

 

Implement a simplified physical based skater animation.

 

Motivation

 

Be familiar with the techniques of human figure modeling, control and specification of character motion. Hope this class project will lead to the further study and research.

 

Related papers and resources

 

            ¡ñ Chapter 7 ¨C ¡°Computer Animation: Algorithm and Techniques¡±  by Richard Parent

¡ñ Robot Dynamics: Equations and Algorithms  by Roy Featherstone and David Orin

            ¡ñ Open Dynamics

¡ñ Animation Lab at Georgia Tech (1999)

                        - Athletic behaviors

                        - Transition (leaping, jumping, balancing and landing)

                        - Hodgins, J. K., Wooten, W. L., Brogan, D. C., O'Brien, J. F., (1995)  Animating Human Athletics. Siggraph '95.

                        - W. L. Wooten and J. K. Hodgins, Animation of Human Diving , Computer Graphics Forum 15(1) pp. 3-13, (March 1996).

- James F. O¡¯Brien, Victor B. Zordan, and Jessica K. Hodgins  Combining Active and Passive Simulation for the Secondary Motion  

 

             ¡ñ CMU Graphics Lab

                        - Physically based character animation

 

             ¡ñ Po-Feng Yang and Joe Laszlo and Karan Singh, SCA '04, Layered dynamic control for interactive character swimming

             ¡ñ Franck Multon¡¯s Papers

             ¡ñ Petros Faloutsos¡¯ papers and dissertation

 

Group Members

            Youri Dimitrov and Cheng Zhang

 

Quarter Plan

-       get a simple model ready;

-       analyze a couple of motion sequences;

-       implement a simplified system of physically based skater animation.

 

 

Week 3 (11 Apr. 2008)

DANCE is a software package for computer graphics and animation research, especially for physical-based character animation. It is developed by people at UCLA Computer Graphics Lab. We spent a lot of time to explore this software this week.

 

DANCE has following main features:

 

DANCE GUI with an articulated object.

 

DANCEGUI.jpg

 

A simple pose of a skater created by using IK chain.

 

simplePos.jpg

 

 

Week 4 (23 Apr. 2008)  

¡¤         More readings:

 

1.    Mechanical Universe: Mechanics and heat

2.    David Baraf¡¯s SIGGRAPH course notes: 95, 97.

3.    Dynamic section: lecture notes

4.    Open Dynamics Engine User guide, ODE tutorial.

5.    SD/FAST user manual

6.    References of rigid body dynamics from Chris Hecker

 

¡¤         Further DANCE exploration

 

1.    Simple Spin Pose (with angular velocity)

    

    

wCollisionPoints.jpg

collisionSphere.jpg

 

                                             The model with collision points.                                                                                                                          The model with collision spheres.

 

     Video1

 

2.    Adding a collision plane.

 

imageWPlane.jpg

wCollisionGeo.jpg

 

                                                  Adding a collision plane with mu = 0.                                                                                                    With the collision geometry.

 

Video2

 

Week 5 - 6(30 Apr. 2008- 6 May 2008)

To have desired motions, except for target poses, we need to create dynamic controllers through scripts and plug-ins. The dynamic control over physically based character animation in Dance is addressed in the following papers. The basic concept is proportional derivative control (PD control).

 

DANCE related papers:

1.    Brian Allen, Derek Chu, Ari Shapiro and Petros Faloutsos, On the Beat! Timing and Tension for Dynamic Characters, ACM SIGGRAPH/EUROgraphics Symposium on Computer Animation (SCA), ACM Press, 2007

2.    A. Shapiro, D. Chu, B. Allen, P. Faloutsos, The Dynamic Controller Toolkit, Sandbox Videogame Symposium, pp. 15-20, San Diego, California, August, 2007

3.    A. Shapiro, P. Faloutsos, V. Ng-Thow-Hing, Dynamic Animation and Control Environment, Graphics Interface 2005, pp. 61-70, Victoria, British Columbia, Canada, May, 2005.

4.    A. Shapiro, F. Pighin, P. Faloutsos, Hybrid Control For Interactive Character Animation, The Eleventh Pacific Conference on Computer Graphics and Applications, pp. 455-460, Canmore, Alberta, Canada, October, 2003

 

What is a PD controller?

PID controller from Wikipedia

Control tutorials from the University of Michigan

           

            Create a simple Plug-in in Dance:

 

pluginImage.jpg

 

                        A Dance plug-in named SimpleTest has been created and added into Dance plug-in pool.

 

           

            Two tests of a simple controller are listed as follows.

 

1.    angular velocity at the root of the articulated objects is 10, friction is 0.01.

 

 

f000008.png

f000020.png

f000027.png

f000034.png

Frame 6

Frame 18

Frame 25

Frame 32

 

 

Video

 

2.    angular velocity at the root of the articulated objects is 15, friction is 0.01.

 

 

f000041.png

f000053.png

f000060.png

f000067.png

Frame 6

Frame 18

Frame 25

Frame 32

 

 

Video

 

            We also use target pose control scheme. The results are listed as follows:

 

           

The initial pose

 

The target pose

initialPose.jpg

targetPose.jpg

 

 

1.    Use the original setup to test the motion. 

 

                        Video

 

2.    Then constrain DOFs of hip and legs.

 

hitRotateParameters.jpg

LThighRotateParameters.jpg

 

 

Video

 

3.    Apply the initial angular velocity 500, 200 to the root.

 

With angular velocity = 500

 

With angular velocity = 200

 

 

Week 8 (20 May 2008)

1.    Circular motion

video

2.    Physically based spin with arms motion

video

3.    Balanced standing

video

 

Week 10 (2 Jun 2008)

 

 

Goal: Triple Jump

 

Triple jump of a ice skater can be modeled by projectile motion which is used to describe the path of any object going through the air under it's own influence.

In order to perform a single, a double, a triple, or even a quadruple jump, an ice skater must jump higher, rotate faster, or do combination of both.

The increase in jump height gives the skater more time to complete the required number of revolutions.

 

http://btc.montana.edu/olympics/physbio/biomechanics/cam03.html

 

video