Upcoming Deadlines

Third Homework (Shooting Reference)Due Tuesday, Feb. 7th (Next week)10 points (5 points if late)

Last day to drop – Monday, Feb. 6th (Next week)

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

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

Homework Assignment #3

Video 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, thrown into the air and falling from about 4-6 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 stays in frame when it’s at the apex of the motion.

Homework #3 (cont.)

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

object so you'll probably need a friend to operate the camera. Be sure to keep the camera level and steady; don’t turn the camera sideways.

Throw the object into the air least 5 times. 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.)Pick one of the throws and find the frame where the

object is at it’s apex, as shown below.

Frame Number

Then find the last frame before you catch it.

Finally, find the middle frame that’s in between those two frames.

Homework #3 (cont.)

Take the images from those three frames and show that the height of the object follows the “Fourth Down at Half-time” Rule.

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

and upload your video clip(s) into that post. In the same posting put an image showing the apex, middle,

and bottom frames. Mark the images, as shown above, to verify the “Fourth Down at Half-time” rule.

This assignment is due by 8am on Tuesday, February 7th (Next week).

15 points (if late, 10 points)

Homework #3 Checklist• In the video your object is thrown upward to a height of between 4-6 feet

(give or take a foot)• You are the person in the video throwing the object• Throw the object at least 5 times, either all in one clip or in multiple clips• Object is clearly visible in all frames going up and down in at least five of

the throws• Find three frames that show the object at it's apex, it's lowest point, and

the frame in between those two• Create an image similar to the example above demonstrating "Fourth

Down at Half-time"• Post your video clip(s) and your "Fourth Down at Half-time" image in a

blog entry entitled "Video Reference"

Extra Credit OpportunityVisit “Renegade Humor” exhibition at the San Jose Museum of Art.

Exhibition opens on February 3rd

Turn in proof of your visit (ticket receipt or photos) for 5 points extra credit. For info: www.sjmusart.org

Extra Credit Opportunity

Academy Award Nominated Animated Short Films

Opens 2/10/2012 atCamera 3 Downtown

Turn in your ticket stub for 5 points extra credit.

Extra Credit Opportunity

Attend any Cinequest Film Festival event in downtown San Jose.Turn in proof of your attendance (e.g., access pass, ticket receipt) for 5 points extra credit.

For info: www.cinequest.org

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

this class. Hit Enter/Send key.* Clicker should read AP123S1* Type in your student ID; hit Enter/Send.Clicker is now ready to use.

Hit any key to wake the clicker from sleep mode.

Entering Student IDIf the clicker does not automatically ask you for your

student ID then you need to do a few more steps:• Press the menu key (star key)• Press the scroll-up key until you reach the menu

option for setting your student ID• Press enter, type in your student ID, press enter

again.

Survey Question

You had some 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.

Review QuestionSometimes animators start with a first drawing plus a rough idea of what they want for action. They then create the second drawing, then the third, etc.This style of animation is called:

First drawing

Imagined Action

A) Drawing-to-DrawingB) One-Two-ThreeC) Straight-AheadD) First-to-LastE) Marching Style

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

You then make the second, the third, etc. until you have all the poses that complete the action.

C) Straight-Ahead

Review Question

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

B)A) D)C)

Odd Rule “Rhythm”

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

B)A) D)C)

1

3

5

Physics of FallingPart II

Straight-Ahead Animation In Straight-Ahead animation, you create the first drawing, then the second one, then the third, etc.

This style of animation is expressive but it can be hard to plan the scene or go back and adjust the timing.

Make the drawings in this order

The “Odd” Rule

“The Odd Rule” tells us that the spacings when slowing out from an apex follow a simple pattern of 1, 3, 5, 7 etc.

This pattern is useful for straight-ahead animation.

Principles of Animation

A 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 drawing

Last 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 Example

A 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)

Homework #3

In the homework assignment you’ll verify the “Fourth Down at Half-time” rule.

Quiz Question: Timing a Fall

Cat falls out of a 4th floor window and lands on the ground; the fall takes 40 frames. How far did he fall in the first 20 frames?

A) A ½ floorB)One floorC)Two floorsD)Three floors

Question: Timing a Fall

B) One floor

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).

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. Mark a keyc) Divide top part in half. Mark a key.d) Divide top part in half. Skipe) Divide top part in half. Mark a key.

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

Prof. Dave ChaiAnimator

a

a

b

c

de

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

Key #2 if 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

Com

ing Dow

n

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 dow

n

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_gHsC2Ehttp://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_gHsC2E

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 seem 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.

Acceleration “Stretch”

Objects do not physically stretch as they fall (not even raindrops).

Objects visually stretch as they gain speed due to motion blur.

Motion blur does not depend on the object’s material, however, it will look more natural for rigid objects to stretch less than elastic objects.

Actual Shape Human eye

Stretch for StrobingIn traditional (hand-drawn) animation stretch is a way of reducing any possible strobing by minimizing the blank spacing between an object’s positions.

In CG animation stretch is not easy with current character rigs but optical effects, such as motion blur, can achieve similar reduction of strobing.

Staying on Model

Animators have to be careful that a character’s features aren’t distorted by stretch to the point where it looks like a different character.

Keeping consistent volumes is essential for “staying on model” when animating.

Clicker QuestionThe effect is often exaggerated for comic effect and gravity does actually physically stretch objects as they fall.

A)TrueB)False

Acceleration “Stretch”B) FalseObjects do not physically stretch as they fall (not even raindrops).

Objects visually stretch as they gain speed due to motion blur.

Raindrop shapes for various sizes

Droplet is spherical once it detaches.

Freefall & WeightlessnessFreefall is the state of weightlessness that occurs during falling, even though gravity is present.

Class Demo: Falling Slinky

Hold a Slinky and its weight stretches it out.

Now drop it. What happens?In freefall it’s in a state of

weightlessness so Slinky immediately contracts.

NASA’s “Vomit Comet”NASA has a special

airplane for training astronauts in free-fall weightless conditions.

The “Vomit Comet” nickname tells you it’s quite a wild roller-coaster ride.

Zero G Corp. offers commercial flights (for $4000)

The plane flies between 20,000 and 30,000 feet, same as commercial flights.

Riding the “Vomit Comet”

http://www.youtube.com/watch?v=2V9h42yspbo

Free Fall in Madagascar 2In parts of this scene they are in weightless freefall… …but not in other parts.

Ready, Set, Zoom (1955)This clip has several examples of stretch.

http://www.youtube.com/watch?v=rv7PWDjjjqk

Ready, Set, Zoom (1955)

Stretch in falling is not realistic.

Stretch due to the law of inertia (drag) does occur.

Stretch AnimationCan accentuate rapid motion blur by using extreme stretch on single frames.

These are consecutive frames from Ready, Set, Zoom.

The Dover Boys (1942)The Dover Boys is a classic cartoon directed by Chuck Jones that has great examples of “stretch” (also called “smear”) animation.

The Dover Boys (1942)

http://www.youtube.com/watch?v=ZtkPMn1Ke4g

The Dover Boys (1942)

Uniform Motion in Profile

In uniform motion, the velocity is constant so the spacing from frame to frame is constant when we view the motion in profile (i.e., object moves from left to right or vice versa).

PerspectiveUniform spacings are visually not uniform when viewed in perspective.

Uniform Motion in Perspective

Uniform motion may not appear uniform due to distortion of scale when shown in perspective.

Distances are equally-

spaced, in perspective

VanishingPoint

Horizon Line

Ball rolling from foreground to background

Falling in Perspective

When falling is viewed from directly above the perspective affects the timing and spacing.

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

Falling in Perspective (cont.)

The “Odd Rule” or “Fourth Down at Half Time” can be used to find the spacings, which determine the object’s size as it moves away from the viewer.

1/24 second intervals

Falling Away or Towards the CameraFalling away from camera

Apex

Last

Middle

Falling towards camera

Last

Apex

Middle

Texture of the timing is extremely different in the two cases.

Falling in Die Hard

An action movie in a 40 story building is going to have lots of good falling scenes.

A building story is about 10-12 feet.

Nakatomi Building in the movie is 400-500 feet

Falling in Die Hard

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

In Recent News…

Falling in Die Hard

In one of the final scenes the villain falls to his death from the top floor.

At 2:02:35

This shot lasts over 12 seconds yet he only falls about one story, which would take about 1 second. For dramatic purposes, it’s filmed in slow motion.

Falling in Die HardIn this shot the villain falls for 5½ seconds, which is the time it takes to fall 40 stories.

At 2:02:45

However, in this shot the stuntman only falls about 20 stories, which takes about 3½ seconds. The director slows the film yet we don’t notice.

The Most Important Law of Motion

The director is always right.

Next LecturePaths of Action

By next Tuesday:Complete the 3rd homework(Shooting Video Reference)

Please turn off and return the clickers!