Upcoming Deadlines

Fifth Homework (Video Analysis of a Jump)Due Thursday, Sept. 29th (In 2 weeks)15 points (10 points if late)

Sixth Homework (Stop-motion Animation)Due Thursday, Oct. 6th (In 3 weeks)20 points (if late, 10 points)Bonus prize of 20 extra points to top three.

For full schedule, visit course website:ArtPhysics123.pbworks.com

Pick up a clicker, find the right channel, and enter Student ID

Tracker Exercise

Drop Exercise

-1.50E+02

-1.00E+02

-5.00E+01

0.00E+00

5.00E+01

1.00E+02

1.50E+02

4.00E+00 4.20E+00 4.40E+00 4.60E+00

Time (s)

Pixel number

mass_A x

mass_A y

Extra Credit Opportunity• Visit the R. Crumb “Genesis”

exhibit (now through Sept.25) at the SJ Museum of Art http://www.sjmusart.org/

• Bring me proof of attendance (ticket stub, photos, etc.) by Sept. 26 for ten points of extra credit

Homework Assignment #5

In this assignment you’ll again use Tracker software to analyze the motion of a moving object from video reference.

First, shoot some reference of yourself doing a running jump.

Position your camera so that you're in frame the entire time that you're in the air.

Stage the jump to be in profile. Shoot at least 5 takes, even if they are

more or less the same.

Homework Assignment #5

Original Video Reference

Homework Assignment #5Import your video reference into the

Tracker software (as in previous homework).

Track the center of your waistline or beltline, which is approximately the location of your center of gravity.

Marking your position from the time you leave the ground until you’ve landed.

After tracking your motion, upload the screen image from Tracker to your blog into a post called "Video analysis of path of action".

Homework Assignment #5

ParabolicPath of Action

Straight Line

Parabolic Curve

Homework Assignment #5

Finally, rewind your video to the first frame of your jump and from the "File" menu select ”Export -> Video Clip".

Choose the export format (.avi, .mov, .gif, etc.) and click "Save As" to save the recording.

Homework Assignment #5

Video Reference with Tracking

Homework Assignment #5

Check that your saved movie has the track showing the path of action then put both clips (original and with tracking) in your blog post using YouTube or Vimeo.

This assignment is due by 8am on Thursday, Sept. 29th (2 weeks from today).

15 points (10 points if late)

Assignment Checklist* Video clip has you running and jumping at least five

times.* On one of the jumps you track the center of your body

while you're in the air.* Show plots for both horizontal (x) position versus time

and vertical (y) position versus time.* Graph of horizontal position versus time is roughly a

straight line.* Graph of vertical position versus time is roughly a

parabolic arc.* Post your screen shot in a blog entry entitled "Video

analysis of path of action".* Post your original reference clip of your five jumps.* Also post a recorded Quicktime movie showing your path

of action for one jump.

Activating your Clicker

* Turn on your clicker.* Enter the channel number or letter for

joining this class. Hit Enter/Send key.* Clicker should read AP123KF11* Type in your student ID; hit Enter/Send.Clicker is now ready to use; leave it on.

Hit any key to wake the clicker from sleep mode.

Survey Question

So far the pace of the class has been:

A)Too fastB)A little fastC)About rightD)A little slowE)Too slow

When you want to throw a ball as far as possible, release it at and angle

of_?a) 15 degreesb) 30 degreesc) 45 degreesd) 60 degreese) 90 degrees

“Shoot the Monkey”

Monkey lets go of the branch the moment he hears the gun fire.

Rifle is aimed at monkey’s nose.

Bullet hits the monkey:A)Above the noseB)On the noseC)Below the nose

Tracking and Motion Graphs

Analyzing Video Reference

Reference is not for rotoscoping (tracing images from a film) but to study the motion.

We can also use video analysis tools to help us see the patterns of motion in a scene that we’ve filmed.

Graph of Ball Drop Heights

Frames

Heig

ht

Notice the shape of the curve made by the dots. This is a parabolic arc.

Tracking a Jump

HorizontalMotion

VerticalMotion

Parabolic Arc

StraightLine

Motion Graphs

In computer animation the timing and spacing of motion is often viewed using motion graphs, which can be manipulated in a graph editor.

Posi

tion

Frame

Autodesk Maya softwareMaya is one of the leading tools

in computer animation.

You will do two homework assignments near the end of the semester using Autodesk Maya.

Motion Graph for Uniform MotionThe motion graph for uniform motion at a constant speed is a straight line.

Posi

tion

Frame

Motion Graphs in Maya

The motion graph for a ball drop looks something like this in Maya

Posi

tion

Frame

Parabolic Arcs

The motion graphs for a ball on a parabolic path of action.

Posi

tion

Frame

HorizontalVertical

Maya Demo for Bouncing Ball

Let me demonstrate how to set up a simple bouncing ball in Autodesk Maya.Our animation will be of a ball that is 4 inches in diameter (2 inches in radius)

The ball will fall from a height of 4 feet (48 inches).

It takes ½ second (12 frames) to reach the ground.

Use Fourth Down at Half Time

Maya Demo for Bouncing Ball

Can add horizontal motion to the bouncing ball as well as bounces at decreasing height.A simple way to make parabolic arcs with apexes of decreasing height is to use the upper part of the previous arc.

Motion Capture & TrackingMotion capture is automated video

tracking.

Data from sensor points can be used to create motion graphs in Maya.

Beowulf (2007)

Using Reference Wisely

Artists know that reference is very important but they also recognize that they shouldn’t be slaves to their reference.

Thomas Eakins,The Swimming Hole (c. 1884)

Photo reference shot by Eakins

Physics helps understand motion yet animators shouldn’t be slaves to it.

Using Physics Wisely

The plane’s path of action feels like a roller coaster drop.

Review QuestionThe motion graph for a ball drop, going from the apex until the ball just touches the ground, looks like:

A) B) C) D)

Motion Graph of a Ball Drop

Frames

Heig

ht

D)

Arcs in Animation

Disney’s Principles of Animation

In their classic book, Disney Animation – The Illusion of Life, Frank Thomas and Olie Johnston list a set of basic principles for animation.1. Squash & Stretch2. Timing3. Anticipation4. Staging5. Follow Through

& Overlapping Action

6. Straight Ahead & Pose-to-Pose Action

7. Slow In and Slow Out8. Arcs9. Exaggeration10. Secondary

Action11. Appeal

Disney’s Principles of Animation

In their classic book, Disney Animation – The Illusion of Life, Frank Thomas and Olie Johnston list a set of basic principles for animation.1. Squash & Stretch2. Timing3. Anticipation4. Staging5. Follow Through

& Overlapping Action

6. Straight Ahead & Pose-to-Pose Action

7. Slow In and Slow Out8. Arcs9. Exaggeration10. Secondary

Action11. Appeal

We have already discussed several of these principles of animation, specifically:

Disney’s Principles of Animation

In their classic book, Disney Animation – The Illusion of Life, Frank Thomas and Olie Johnston list a set of basic principles for animation.1. Squash & Stretch2. Timing3. Anticipation4. Staging5. Follow Through

& Overlapping Action

6. Straight Ahead & Pose-to-Pose Action

7. Slow In and Slow Out8. Arcs9. Exaggeration10. Secondary

Action11. Appeal

Today we will discuss arcs and how they relate to animated motion.

Arcs of Motion

Motion usually follows an arc, which may be simple, like a circle, or very complex and irregular.

Importance of Arcs

One of the major problems for the inbetweeners is that it is much more difficult to make a drawing on an arc.Drawings made as straight inbetweens completely kill the essence of the action.

Disney animation legends Frank Thomas and Olie Johnston write:

Wrong

Right

Circular Arcs

Circular arcs are common since motion is often around a fixed pivot point, such as a joint.

Speed in Circular Motion

Rotational Speed: Revolutions per secondTangential Speed: Total distance per

secondSame Rotational Speed

Different Tangential Speeds

Rolling & Slipping

1 2 3 4 5 6 7

Rolling ball turns one revolution when it travels a distance equal to three times its diameter (actually 3.1416 diameter)

ROLLING

1 2 3 4 5

SLIPPING

Slipping and rolling are both uniform in spacing and rotation.

Throwing ArmTangential

Speed

The longer the throwing arm, the greater the tangential speed so the farther it can throw. Sling lengthens

the arm at almost no cost in the weight.

Doubling the speedquadruples the range!

x2

Timing on Circular Arcs

In this golf swing the motion:• Slows out (accelerates) to hit the ball• Uniform after the hit• Slows in as the swing finishes follow-through

A circular arc is a simple path of action but the timing may be complex and textured.

Slow out

Unifor

m

Slow in

Non-Uniform Circular MotionTwo common types of motion on circular arcs that have non-uniform timing and spacing are:

Exponential Spacing Pendulum Spacing

Example:Tipping over

Example:Stride inwalking

Pendulum SpacingA pendulum’s path of action is also a circular arc but the spacing is very different from the exponential spacing of tipping over.

Spacing & Timing in Swinging

A pendulum will slow in and out as it swings back and forth, the same as a ball rolling in a half-pipe.

Most of the texture in the timing is at the endpoints; the timing is even in the center.

Pencil Test Example

http://www.youtube.com/watch?v=xuoJdNGxffU

Motion Graph for PendulumThe motion graph (angle vs. frame) shows that the timing is mostly textured (curves the most) at the apexes.

Frame

An

gle#1

#4

#7

FASTFAST

SLO

W

SLOW

SLOW,again

SLO

W,

agai

n

Ball goes fastest around the bottom but the speed is almost constant.

Uniform Rotation in PerspectiveThe timing for uniform rotation has texture when seen in perspective.

Half orbit

Quarterorbit

Rotation from key #1 to #5 in background takes twice as long as from #6 to #8 in foreground.

Swinging in Perspective

Visually the timing has even more texture when the swing occurs in perspective.

Demo: Don’t FlinchPendulum swings back and forth yet it

doesn’t hit your face.

Bowling Ball Pendulum

This video clip lets you experience what it’s like to do this demo.

Click

http://www.youtube.com/watch?v=UNsD15GjWWE

Who Framed Roger Rabbit? (1988)

The opening sequence in Who Framed Roger Rabbit? makes great use of the textured timing of arcs in perspective.

Animation byRichard Williams

Who Framed Roger Rabbit? (1988)

http://www.youtube.com/watch?v=sLNqtU-gYPc