ID 750 Fall 2000 - Expressive Motion

Assignment : Using Timing to Visually Define Weight

"Timing, more than anything else, defines the weight of an object."
John Lasseter, Pixar

quicktime movies

Assignment goals:
The student will explore different types of motion for the classic animation exercise, The Ball Bounce. By incorporating squash and stretch, arcs of motion, slow in/slow out, the student will increase their understanding and sensitivity to motion and its implications.

Minimum requirements:
It is the goal of the student to use 2 primitive spheres as balls and to give each of the balls its own distinct properties, by the use of different approaches in timing and motion. One ball is to be visually described with timing and deformations as a soft surface ball and the other should be visually described as a hard surface ball.

Animation length will be no more than five (5) seconds.

Assignment introduces:

• consideration of gravity and friction as a factor in movement
• Newton's second Law of Motion
When a force acts on an object, the object accelerates in the direction in which the force is acting. A force acting on a moving object will speed it up, slow it down, or change the direction in which it is moving.
• The amount of kinetic energy, the energy of movement, depends on the amount of matter and speed of the moving object.
• collision and absorption or the effect of an outside force (the floor)
• decay at top of a motion curve
• placement of keyframes as animation progresses
• 1, 2 or 3 frame stick on the squash, An elastic object changes shape when a force acts on it, but regains its shape when the force stops. Regaining its shape, causes it to push against the ground and bounce so that it also regains its kinetic energy.
• set driven keyframe for squash/stretch
• expression for squash/stretch
ball.scaleX = sqrt(1/ball.scaleY);
ball.scaleZ = sqrt(1/ball.scaleY);
• non-linear squash deformer

Assignment requirements:

• Animation will contain the bounce of a heavy ball (baseball) and a light ball (rubber ball)
• Students will study these balls and their movements
• The environment will be a simple floor plane on which the balls bounce
• The camera will be stationary
• Animation will be rendered in wireframe
• All geometry will be from primitives
• No software dynamics will be used

• Timing for Animation, Whitaker and Halas, Animation and Properties of Matter, pg. 26-27
• Timing for Animation, Whitaker and Halas, Newton's Law of Motion, pg. 32-37
• Principles of 3D Computer Animation, O'Rourke, Shape Changes, pgs. 175 - 179
• Principles of 3D Computer Animation, O'Rourke, Expressions, pgs. 190 - 196
• The Animators Workbook, White, Inbetweens and Slow In/Out, pg. 26 and 28
• The Animators Workbook, White, Weight in Movement, pg. 74-75
• The Animators Workbook, White, Dope Sheet and TV Safe, pg. 88-89, and pg. 93

Tutorials:

• Learning Maya 2.0, online pdf by Alias|Wavefront, Lesson 1, A Bouncing Ball
• Learning Maya 2.0, online pdf by Alias|Wavefront, Lesson 2, Adding Character

PDF file for the Learning Maya 2.0 tutorials is in Network Neighborhood\Grumpy\MayaDocs\

Principles of 3D Computer Animation by Michael O'Rourke pgs. 147 - 161
Timing in Computer Animation, by John Lasseter

1. Research- Sign out ACCAD's video camera and video tape the two different balls when they are dropped to the floor. Look through your footage and select the best bounce for each ball. Find other video reference by looking a animation, traditional and computer-generated. Save these as reference movie files in your home space.
Video reference in movie files Due Friday, September 29th

Web Reference:
How Things Work: Bouncing Balls
Bouncing Balls

2. Analysis- Create a timing sheet from your movie files of the bounce. Start with 150 frames (5 seconds x 30 fps) and while you are viewing the movies frame by frame, mark down how many frames it takes between the ball drop and the bounce and back to the top of the ball arc, etc.
In your sketchbook, make notes and drawings which illustrate the key positions of the ball and its shape change as it contacts the floor. Use this to guide timing and key poses for your animation.
Timing Sheet and Drawn key poses Due Monday, October 2nd

3. Animation approach- This animation will be "blocked in" with key poses to establish the broad motion of the movement. The blocked in motion gives you a rough look at the timing of the piece as a whole. You will layout the piece from beginning to end showing the broad motion. This would be translation on the translation node and the addition of squash and stretch once the keyframes for the translation are established. The timing of the key frames will come from the analysis that you did and from your sketchbook drawing reference.
NOTE: Simplicity is the key to this project. Keep in mind the focus of the assignment is in the 2 balls' motion and distingishing between a hard and soft surface ball.

4. Assignment Due Dates

Wednesday, September 27th
Workshop on Digital Video and making movies with Barb Helfer
Shoot video of balls, make movies
Gather reference materials
Create a timing sheet from video reference

Friday, September 29th
DUE: Movie Files from video reference
DUE: Learning Maya, Lesson 1: Bouncing a Ball (playblast)
DUE: Learning Maya, Lesson 2: Adding Character (playblast)

Monday, October 2nd
Critique: Swinging Boxes
Introduction to Ball Bounce
DUE: Timing Sheet and Drawn key poses

Wednesday, October 4th
Workshop on Video Facility with Barb Helfer
Continued work on motion

Friday, October 6th
Critique: animation of Ball Bounce w/2 balls (Hardware Render)
Continued work on motion

Monday, October 9th
Final Critique: animation of Ball Bounce w/2 balls - on VHS

Wednesday, October 11th
DUE: animation of Ball Bounce with sound - on VHS and as Quicktime movie file
DUE: animation of Pendulum - on VHS and as Quicktime movie file
DUE: animation of Swinging Boxes - on VHS and as Quicktime movie file