Upcoming Deadlines

Third Homework (Shooting Reference)Due Thursday, September 8th ;10 points (5 points if late)

LABOR DAY – Campus closedMonday, September 5th (Next week)

Last day to drop – Tuesday, Sept. 6th

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

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

Homework Assignment #3Video reference is a useful aid in creating

animation and often animators have to shoot their own reference to suit their needs.

Your homework assignment is to shoot video reference of an object, such as a ball or a water bottle, falling straight down from a height of about 4 feet.

Plan your scene so that the object is clearly visible on each frame; make sure that the background is uncluttered. Stage the scene so that the object is in frame from the moment of release until it hits the ground.

Homework #3 (cont.)You have to be the person in the video dropping

the object so you'll probably need a friend to operate the camera. Be sure to keep the camera level and steady; the simplest way to do this is to set the camera on a chair or table.

Shoot at least 5 takes, even if they are all more or less the same. You can record one long clip or several short clips.

Note that many digital cameras have a movie mode and you can check out digital camcorders from the Instructional Resource Center on campus.

Homework #3 (cont.)Find out the frame rate at which your video

camera records; many of them record at either 15 or 30 frames per second instead of the usual 24 frames per second used in animation.

A simple way to determine the frame rate is to count the number of frames that it takes the object to fall from a height of 4 feet and consult the table below:

7-8 Frames - 15 frames per second 12 Frames - 24 frames per second 15 Frames - 30 frames per second

Homework #3 (cont.)

Homework #3 (cont.)Create a post on your course blog entitled "Video

Reference" and upload your clip(s) into that post.

Keep your clips because you will need them for the

next homework assignment.

This assignment is due by 8am on Thursday, September 8th (week from today).

10 points (if late, 5 points)

Homework #3 Checklist• In the video your object dropped from a height

of about 4 feet (give or take a foot)• You are the person in the video dropping the

object• Drop object at least 5 times, either all in one clip

or in multiple clips• Object is clearly visible in all frames in at least

five of the drops• Post your clip in a blog entry entitled "Video

Reference"• In the same blog entry give the frame rate of

your camera (probably 15 or 30 frames per second)

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

joining this class. Hit Enter/Send key.* Clicker should read AP123GF10* Type in your student ID; hit Enter/Send.Clicker is now ready to use.

Hit any key to wake the clicker from sleep mode.

Survey QuestionYou had problems putting video

into your blog posting.

True (T) or False (F)

Note: You score 1 point of credit for answering survey questions, regardless of your answer.

Physics of FallingPart II

Principles of AnimationA principle of animation is that there are two basic styles,Straight Ahead and Pose-to-pose.1. Squash & Stretch2. Timing3. Anticipation4. Staging5. Follow Through

& Overlapping Action6. Straight Ahead & Pose-to-Pose Action

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

Action11. Appeal

Straight-Ahead AnimationIn Straight-Ahead animation, you have a first drawing and a rough idea of what you want for action.

First drawing

Images in your head

Next, we want to have some idea as to how many drawings will take us from this first key pose to that conclusion of the action

First drawing

Images in your head

Straight-Ahead Animation (cont.)In Straight-Ahead animation, the next step is to decide on the second drawing and draw that frame.

Second drawing

The table also tells us that after four frames the ball falls 5 1/3 inches so that’s its position from the apex for key #3.This is correct but measuring the position for every drawing is a very boring and tedious way to animate!

Straight-Ahead for Ball DropTime (sec)

Frames

Distance fallen from apex

1/24 1 1/3 inch1/12 2 1 1/3 inches1/8 3 3 inches1/6 4 5 1/3 inches

Apex2 frames

4 frames

6 frames

Seeing the Rhythm

From Preston Blair’s, Cartoon Animation

It’s good to know how quickly objects fall but animators do not calculate the motion.

Animators see the patterns in how the motion slows in and out.

The “Odd” RuleFor a falling object, the distance between drawings follows a simple pattern, which we’ll call “The Odd Rule” because it uses the odd numbers, 1, 3, 5, 7, etc.Distance between keys increases in the ratios 1:3:5:7:9… starting from the apex drawing (key #1).

Rolling Downhill

Rolling downhill isalso accelerating motion

Very similar to falling except distances are smaller and depend on the slope of the incline.But the distances always go as 1:3:5:7:9:etc.

Key #1 is point of release

Class Demo: Galileo’s RampsRoll wheels down notched, inclined

ramps and listen for the clicks.

Start

8 8 8 8 8 8 8 8

7 9 11 131 53 15

Downhill

Click-----Click----Click---Click--Click-ClickClick

Click--Click--Click—Click--Click--Click--Click

Deceleration by FrictionSpacings when decelerating by friction also follow the Odd Rule, slowing into the final key (coming to a stop).

#1 #2 #3 #4

Many (but not all) cases of slowing in/out follow the “Odd Rule”

Odd Rule “Rhythm”Learn to recognize the spacing “rhythm” of the odd rule for slowing in and slowing out.

1

3

5

Apex

Odd Rule “Rhythm”

Which of these spacings has the proportions of the Odd Rule?

A) B) D)C)

Odd Rule “Rhythm”

With practice you’ll easily recognize the Odd Rule rhythm.

A) B) D)C)

1

3

5

We know that key #2 is a third of the ball’s diameter below key #1 (point of release or apex). A)

B)

C)

D)

Roughly where do you draw the ball on key #3?

Straight-Ahead for Ball Drop

C)By the Odd Rule the spacing between keys #2 and #3 is three times the distance from #1 to #2. So key #3 is one diameter lower than key #2.

C)It’s easy to estimate this 1-to-3 ratio in the spacings by eye.

Straight-Ahead for Ball Drop

Principles of AnimationA principle of animation is that there are two basic styles,Straight Ahead and Pose-to-pose.1. Squash & Stretch2. Timing3. Anticipation4. Staging5. Follow Through

& Overlapping Action6. Straight Ahead & Pose-to-Pose Action

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

Action11. Appeal

Pose-to-Pose AnimationIn Pose-to-Pose animation, the first step is to create the first and last drawings.

First drawingLast drawing

Also decide how many drawings to put in between the first and the last.

Pose-to-Pose Animation (cont.)Next, you create the drawing that goes half-way between the first drawing and the last drawing

“Breakdown” drawingFirst key

Last key

Pose-to-Pose Animation (cont.)Finish by creating any remaining “in-between” drawings.

“In-between” “In-between”

Pose-to-pose is less spontaneous than straight-ahead but it’s easier to plan a scene from its start and end.

A Fourth Down at Half Time

3 frames per drawing(close-up)

6 frames per drawing(medium shot)

In time, Key #3 is half way between #1 and #5.

In space, Key #3 is a fourth of the way down between #1 and #5.This rule always applies for any key half-way in time from the point of release.

First

Last

Break-down

Break-down

Last

First

Ball Drop ExampleA ball drops from 4 feet high.

Key #4 is the half-time key (half way between #1 & #7).

The distance from the apex to the half-time key (#4) is a quarter of the way down (1 foot below apex)

Question: Timing a FallCat falls out of an 8th floor window and falls one floor (about 12 feet) in 20 frames. How far does he fall in the next 20 frames?A)One floorB)Two floorsC)Three floorsD)Four floorsE)Seven floors

(Hits ground)

Question: Timing a FallC) Three floors

The first 20 frames is “half time” of 40 frames total so the cat is a fourth down at that point.

In the next 20 frames he falls the other 3/4

ths of the distance from the apex.

Apex

First 20 frames

Next 20 frames

Falling Cathttp://www.youtube.com/watch?v=QhGOvkQBgK0

Cat falls from a height of 80 feet in about 65 video frames (30 fps).

Drawing In-betweensDrawing in-betweens refers to adding extra drawings in frames in between the key pose drawings.To draw in-betweens of accelerating motion, divide the first spacing by FOUR, then keep the same ratios of 1:3:5:7.

Drawing In-betweens (cont.)Notice that the first in-between drawing is positioned rather close to the apex drawing.

The other in-between drawings, although not exactly in the middle, are close to being half- way between the keys.

Falling a la Chai

An approximation to real falling that’s easy to use for pose-to-pose animation Recipe for “Falling a la Chai”:a) Draw interval from first & last keys.b) Divide interval in half. c) Divide top part in half.

Mark this key as the middle key.d) Divide top part in half.e) Divide top part in half. Mark a key.f) Mark another key at spot b)

Key #4 is a bit too high but who’ll notice?

Prof. Dave ChaiAnimator

a

a

b

cde

PhysicalFalling

Falling a la Chai

Falling a la Chai (cont.)Falling a la Chai uses Fourth Down at Half Time. In fact, it uses it twice.

PhysicalFalling

Falling a la Chai

Key #3 is a fourth of the distance down and is half-way in time between keys #1 and #5Key #2 is a fourth of the distance down and is half-way in time between keys #1 and #3

Up and DownFor a ball moving upward the timing and spacing as it slows into the apex is the same as when it falls downward and slows out of the apex.

Going up

Coming Down

This picture is physically correct but animators tend to shift the up and down positions slightly to avoid an optical illusion called strobing.

“Hitting the Ceiling”If the spacings near the apex aren’t quite right then the ball reverses direction at the top in an unnatural way.

It’s as if the ball hits and bounces off of an invisible ceiling.

Going up, then down

RightWrongVeryWrong

“Hitting the Ceiling” Example

This ball seems to hit an invisible ceiling near apex.

Here the slowing in and out of the apex is pretty good.

Wrong Right

http://www.youtube.com/watch?v=AL6i_gHsC2E

http://www.youtube.com/watch?v=7HPdSQIJXfE

Perception of Motion*Fundamental requirement for realism in animation is the Perception of Motion.

* Often (inaccurately) called “Persistence of Vision”

This illusion occurs when a sequence of images is interpreted by the brain as apparent motion.

Called Beta Movement. http://www.youtube.com/watch?v=AL6i_gHsC

2E

StrobingWhen the action is slow, the overlapping of an object from one frame to the next helps maintain the perception of motion.When the action is too fast, the perception of motion can be lost because the object seems to disappear and reappear.

In animation this is known as strobing

Strobing Example

The ball seems to appear and disappear around the top and bottom of the bounce.

This animation preserves the perception of motion.

Strobing No Strobing

Strobing more noticeable in your peripheral vision.

http://www.youtube.com/watch?v=QrgtxGQfG9g

http://www.youtube.com/watch?v=AL6i_gHsC2E

Wagon Wheel IllusionThe wheel seems to spin backwards because our perception of motion is confused due to strobing.

Often seen in westerns

Example of Wagon Wheel Illusion

Propeller is spinning faster and faster but the video camera has a fixed frame rate that sometimes syncs with the propeller’s rotation.

http://www.youtube.com/watch?v=UkotZy3lQqo

Class Demo: Strobe LightStrobe lights are high-powered lamps with a periodic timer that allows it to flash at a fixed rate.

Can demonstrate strobing and the wagon wheel effect.

Nyquist Effect

The brain tracks the movement of the spokes by looking for the nearest location on each frame. The Nyquist effect limits how fast a wheel can spin in an animation and still be seen as turning.

ActualRotation

Illusion

#1#2

Wheel on frames#1 and #2

Wagon wheel illusion is an example of the Nyquist effect.

Next LecturePaths of Action

By Thursday (week from today):Complete the 3rd homework(Shooting Video Reference)

Please turn off and return the clickers!

NO CLASSES ON MONDAY (LABOR DAY)