Upcoming Classes

1
Upcoming Classes

• Tuesday, Sept. 11th
• Motion and Dance, Part 1
• Assignment due
• Read Motions without Turns, Physics and the
  Art of Dance, K. Laws, Pages 36-51
• Thursday, Sept. 13th
• Motion and Dance, Part 2
• Assignment due
• First draft of first oral presentation or
  written paper

2
Upcoming Deadlines

• Thursday, September 13th
• First draft of your first term paper or your
• oral presentation
• Thursday, September 27th
• First Set of Oral Presentations
• First term paper (if not giving presentation)

3
Oral Presentations

• The following persons will give oral
  presentations on Thursday, September 27th
• Batres, Adan
• Boyd, Heidi
• Chen, Emily
• Kwiatkowski, Dajon
• Lebedeff, Christopher
• Lipton, Christopher
• For everyone else, your first term paper is due
  on that date.

4
Extra Credit SF Museum of Art

• Visit San Francisco Museum of Modern Art and see
  Abstract Expressionist paintings.
• Turn in your ticket receipt (7 for students).
  Worth one homework assignment deadline is Oct.
  16th

Guardians of the Secret, Jackson Pollock, 1943
5
Quiz

• Put your name on a sheet of paper and answer the
  following question from todays reading
  assignment
• In animation, what is meant by the expression
  slowing out? Give an example of slowing out.

6
Pollock Extra Credit (1)

• In the movie Pollock theres a scene in which
  Jackson Pollock goes to a store and trades one of
  his paintings for something which he then brings
  home riding a bicycle.
• What is it that Pollock gets from the store and
  what happens on his way home from the store?

7
Pollock Extra Credit (2)

• In the movie Who the Fck is Jackson Pollock
  the forensic detective investigating Teri
  Hortons painting finds something interesting on
  the back of the painting, which leads him to
  visit Pollocks original art studio.
• What is it that he finds and why does he need to
  visit Pollocks studio?

8
Motion in Real Animated Worlds
9
Real World Animated World
Understanding the real world helps in creating
interesting animated worlds.
"Animation follows the laws of physics unless
it is funnier otherwise. Art Babbitt, Disney
animator, director, and creator of Goofy
10
Motion Mechanics
The study of motion is a fundamental field of
physics known as mechanics.
In order to do the fantastic we must first
understand the real. Walt Disney
11
Motion Mechanics
Physical laws apply equally to living characters,
living beings are just a little more complex (but
then so is an automobile engine)
Thomas Eakins
12
Computer Generated Animation

• Animation software, such as Maya, have
  sophisticated physics engines that use the laws
  of physics to compute motion.

13
The Four As of Animation

• In his book, Animation, The Mechanics of Motion,
  Chris Webster lists the following four levels for
  animated motion
• Activity (arbitrary movement)
• Action (physical motion)
• Animation (purposeful motion)
• Acting (motion with personality)
• These categories are best understood by
  considering specific examples.

14
Activity (Level 1)
The opening sequence in the Star Wars movies is
a good example of activity, the lowest level of
animated motion.
The motion is arbitrary, without constraint of
physical laws.
That moving ball was another example of activity.
15
Action (Level 2)
Action is the level of animation when objects
move according to physical laws, such as a
bouncing ball or a waving flag.
16
Animation (Level 3)
At this level the motion not only follows the
physical laws but is also intentional, such as a
bird flapping its wings or a humans throw.
17
Acting (Level 4)
At this highest level not only is the motion
intentional but it also conveys personality.
18
The Four As of Animation (again)

• Activity (arbitrary movement)
• Action (physical motion)
• Animation (purposeful motion)
• Acting (motion with personality)
• Physics is important in the first three levels
  and you cannot achieve acting without those first
  three levels.

19
Disneys Principles of Animation

• Squash Stretch
• Timing
• Anticipation
• Staging
• Follow Through Overlapping Action
• Straight Ahead Pose-to-Pose Action
• Slow In and Slow Out
• Arcs
• Exaggeration
• Secondary Action
• Appeal

(from Disney Animation The Illusion of Life, by
Thomas and Johnston)
20
Its all in the timing
An essential element of animation is the timing
between frames
Its not important what goes on each frame of
film its the spaces between the frames that are
important. Norman McLaren
21
First Film The Bouncing Ball

• To learn basic timing, all animation students
  begin with the same film the bouncing ball

22
Timing Frames, Keys, Clocks

• Well use three different ways of measuring time
• Frames (intervals of 1/24th of a second)
• Keys (given number of frames between poses)
• Clocks (actual seconds as measured by a clock)
• IMPORTANT Well select the keys such that there
  are always the same number of frames between each
  key.

23
Uniform Motion
1
2
3
4
5
Equal Distances
Arbitrary
Rolling ball is an example of uniform
motion. Velocity of the ball is constant (with no
friction).
NOTE In all examples there are an equal number
of frames between keys
24
Uniform Motion in Perspective
25
Uniform Motion in Perspective
Uniform motion may not appear uniform due to
distortion of scale when shown in perspective.
Vanishing Point
Horizon Line
Distances are equally-spaced, in perspective.
26
Accelerating Motion Falling
1
1
1
Falling is an example of accelerating motion (in
animation, slowing out).
2
4
3
Distance between keys increases in the ratios
13579 starting from point of release (key
1).
3
Total distance from point of release (key 1)
increases in the ratios 1491625 or
1222324252
9
5
In Straight Ahead animation after drawing keys
1 and 2 the positions of the rest are given by
these rules.
4
7
16
27
Distance Fallen
Time (seconds) Frames Distance fallen (key 1 to 2)
1/24 1 1/3 inch
1/12 2 1 1/3 inches
1/8 3 3 inches
1/6 4 5 1/3 inches
¼ 6 1 foot
1/3 8 1 ¾ feet
½ 12 4 feet
2/3 16 7 feet
¾ 18 9 feet
1 24 16 feet
Distance fallen from key 1 (release point) to
key 2 depends on the number of frames between
keys. Distance fallen from key 2 to 3 is three
times further from 3 to 4 is five times, from
4 to 5 is seven times, etc.
Note These distance do not depend on the
objects weight.
28
Falling Bowling Ball
1 (Release)
1 (Release)
2
2
Bowling ball is one foot in diameter. Balls
falls by one diameter in the first six frames.
Same times
3
3
4
4
Falls ¼ of diameter in the first three frames.
5
5
6 frames per key
3 frames per key (and dolly in)
29
Demo Catch a Buck
Put thumb and index fingers near Washingtons
head. Can you react fast enough to catch the
money?
Half length of dollar bill is 3 inch so it takes
about 1/8 of a second (0.125 seconds) to fall
this distance. Typical reaction time is 0.20 to
0.25 seconds.
30
Measuring Reaction Time
Distance (inches) Time (sec.) 1
0.07 2 0.10 3 0.12 4
0.14 5 0.16 6 0.17 7
0.19 8 0.20 10 0.23 12
0.25 14 0.27 16 0.29 18
0.30
Release
Catch
31
Rolling Downhill
1
Key 1 is point of release
1
3
2
5
3
7
4
Rolling downhill is also accelerating motion
Very similar to falling except distances are
smaller and depend on the slope of the incline.
32
Demo Galileos Clicking Ramps

• Roll balls down notched, inclined ramps and
  listen for the clicks.

8 16 24 32
40 48 56 64
Start
1 4 9 16 25
36 49
64
42x2 93x3 164x4 255x5
366x6 497x7
648x8
33
Sliding with Friction
Block stops here
Sliding this way
3
1
5
1
2
3
4
Sliding with friction is another example of
accelerating motion but in this case the object
slows in. Draw last key (where object stops)
first and draw keys leading up to it in the
ratios 13579
34
Speed Lines and Acceleration
Block stops here
Speed lines used to indicate velocity
1
2
3
4
With Friction
In accelerated motion, the velocity increases or
decreases uniformly (e.g., velocity with friction
could go from 6, to 4, to 2, and finally zero)
3
1
2
Without Friction
In uniform motion, the velocity remains constant
(no acceleration)
35
Falling and Floating
Light objects, such as a beach ball, initially
fall with accelerating motion. Due to air
resistance, the motion transitions to uniform
motion after falling a certain distance. For
very light objects, such as a leaf, this
transition is almost immediate.
1
3
Accelerating Motion
5
Uniform Motion
5
5
Squirrels cannot die from a fall.
5
36
Hyper-acceleration
1
Constant acceleration
1
3
Release
2
5
3
7
1
4
Release
2
3
Hyper-acceleration
4
If the slope of an incline increases, the
acceleration itself accelerates.
37
Tipping Over
Brick tipped 2º off-balance then released.
A good example of hyper-acceleration is an object
tipping over when off-balance.
Release
At 4º in ½ second
At 15º in 1 second
At 57º in 1½ second
No simple way to compute hyper-acceleration.
38
Acceleration Stretch
Objects visually stretch as they gain speed due
to motion blur.
Objects do not physically stretch as they fall
(not even raindrops).
Motion blur does not depend on the objects
material, however, it will look more natural for
rigid objects to stretch less than elastic
objects.
High-speed camera
Human eye
39
The Dover Boys

• The Dover Boys is an animation classic by Chuck
  Jones (better known for Bugs Bunny, Daffy Duck,
  Road Runner, and others).
• This cartoon has great examples of extreme
  stretch, also called smear animation.

40
Moving Falling
2
1
4
3
1
5
Arbitrary
3
Ball rolling off of a table combines horizontal
and vertical motion. Falling starts with key 4,
with vertical distances increasing as
1357 Horizontal distances equally spaced as
with uniform motion. Arc is the combination of
uniform horizontal motion and accelerating
vertical motion.
6
5
7
7
41
Demo Fall and Fire
FALL
1
FIRE
1
1
One ball is released and falls straight
down. Other ball is fired horizontally. At all
times the balls are at the same height. Hit the
ground at the same time.
2
2
3
3
3
5
4
4
42
Parabolic Arc of Motion
4
1
3
5
Apex
Arbitrary
3
2
6
Up and down motion is symmetric, as shown. Key 4
is highest point of the arc of motion.
5
7
1
7
43
Bouncing with Squash Stretch
Stretch is added where motion is the
fastest. Squash is used to emphasize impact on
bounce.
44
Parabolic Arc in Perspective
Maximum height (ball at midpoint)
VP
HL
Ball starts and ends on the ground.
45
Parabolic Arc in Perspective (cont.)
1
VP
HL
3
Add points to the curve by tweening from the
point of maximum height.
46
Maximum Range

• Maximum range is at 45 degrees
• (when air resistance is negligible).

47
Demo Trebuchet

• Trebuchet is a type of catapult popular in the
  13th century.

Warwolf
Release
48
Movie Trebuchet
Contestant in annual pumpkin throwing contest,
Punkin Chukin
49
Next Lecture Motion Dance (I)

• Remember
• Read Motions without Turns, Physics and the Art
  of Dance, K. Laws,
• Pages 36-51