Upcoming Deadlines Have clicker ready Sixth Homework Stopmotion

Upcoming Deadlines Have clicker ready Sixth Homework (Stop-motion Animation of Falling) Due Tuesday, Sept. 25 th (Next week) 20 points (if late, 10 points) Bonus prize of 20 extra points to top three. Seventh Homework (Outline of First Term Paper) Due Tuesday, Oct. 2 nd (In two weeks) 10 points (5 points if late) For full schedule, visit course website: www. Animation 123. com

Special Campus Event Hear Randy Dutra discussing his animation work on Jurassic Park I & II. This Friday at 1 pm in Washington Square Hall Room 207 No extra credit but worth attending anyway.

Extra Credit Opportunity Visit the Cartoon Art Museum in SF to see the Avengers Assemble! exhibition. Exhibit runs until Oct. 7 th Turn in proof of attendance (ticket receipt) for 10 points extra credit. For info: cartoonart. org

Extra Credit Opportunity Attend a screening at Palo Alto International Film Festival (Sept. 27 -30) Turn in proof of attendance (ticket receipt) for 10 points extra credit. For info: http: //paiff. net/

Extra Credit Opportunity Attend a screening or event at the Mill Valley Film Festival (Oct. 4 th -- 14 th) Turn in proof of attendance (ticket receipt) for 10 points extra credit. For info: www. mvff. com

Homework Assignment #6 Stop-motion animation of a falling object. * Plan your scene, especially the timing, spacing, path of action, anticipation, etc. * Photograph your object in a sequence of images suitable for combining into an animation. * Create a video clip with at least a dozen unique frames. * Adjust the timing by adding or removing frames; if needed, re-shoot your animation.

Homework Assignment #6 * Post your animation to your blog in an entry entitled "Stop Motion Animation of Falling". * In your posting describe in one paragraph how you created your animation. Due by 8 am on Tuesday, Sept. 25 th 20 points (if late, 10 points) Score based on believability and creativity. The top three animation clips in the class will receive a bonus of 20 extra points.

Homework Assignment #6 Here is a good example from another semester. Not only does the falling motion look believable but the action is simple yet entertaining. http: //www. youtube. com/watch? v=u. OTncsocs. UE

Survey Question Have you already started working on your stop-motion animation due next week? A) Yes B) No

Review Question A spool is pulled by a string, wrapped around the center, as shown. The spool will move: A) Left B) Right Pull

Force and Direction A) Left Objects always change their velocity in the direction of the applied force. Pull Motion Pull

Review Question With the air is pumped out of the interior of a pair of Magdeburg hemispheres they are very difficult to pull apart. If the air pressure in the room goes down, then the force holding the hemispheres together: A) Decreases B) Increases C) Is unchanged

Demo: Magdeburg Hemispheres A) Decreases The force pressing the hemispheres together comes from the difference of pressure between the inside and outside. A A L A A A - Atmospheric pressure L - Low pressure

Review Question Blow hard through a funnel with a ping pong ball in the funnel’s bowl. Instead of being blown away, the ball is held tightly in the bowl. This is because: BLOW Ping Pong Ball A) Compression produces low pressure B) Moving air produces low pressure C) The ball spins, producing low pressure D) None of the above

Class Demo: Blow the Funnel B) Moving air produces low pressure. This demonstrates the Bernoulli effect, which says that the higher the air speed, the lower the pressure. BLOW L Ping L Pong Ball A

Squash and Stretch

Character Animation In the first part of the course we’ve covered some of the basics of animation. We now move to more advanced topics, specifically those relevant to character animation.

Snow White Disney’s Snow White was the first full-length feature film using traditional (cel) animation. Snow White (1933, 7 min. ) Snow White and the Seven Dwarfs (1937, 83 min. )

Snow White (1933) http: //www. youtube. com/watch? v=IUsp 2 Xxg. ZTY

Snow White (1937) http: //www. youtube. com/watch? v=n. N 1 Beg. E 3 QR 0

Disney’s Principles of Animation From life studies, Disney animators discovered that #1 principle that was key to adding realism in character animation was “Squash & Stretch. ” 1. Squash & Stretch 2. 3. 4. 5. Timing Anticipation Staging Follow Through & Overlapping Action 6. Straight Ahead & Pose-to-Pose Action 7. Slow In and Slow Out 8. Arcs 9. Exaggeration 10. Secondary Action 11. Appeal

Basic Squash & Stretch shows speed due to motion blur. Basics of squash and stretch are present in even the simple ball bounce exercise. Actual Shape As Seen by Human Eye Cartoon Squash shows force, such as on impact.

Character Animation Basic squash and stretch are easy to learn from a bouncing ball but their importance is in how squash and stretch appear in the motion of characters. From Preston Blair’s, Cartoon Animation

Luxo Jr. ’s Squash & Stretch “An object need not deform in order to squash and stretch. For instance, a hinged object like Luxo Jr. squashes by folding over on itself, and stretches by extending out fully. ” John Lasseter

Luxo Jr. (1986) Luxo Jr. was the first CG film nominated for an Academy Award. http: //www. youtube. com/watch? v=Pv. CWPZf. K 8 p. I

Water Balloon Drop Water balloon is a good animation exercise because it moves like an animate character. By Mai Vu http: //www. youtube. com/watch? v=aj. C 1 o. CZlk. QI By Ken Calvert http: //www. youtube. com/watch? v=0 y. WTJpao. JXI

Water Balloon Reference http: //www. youtube. com/watch? v=FI-Mq 6 BDt. MQ It’s always useful to animators to study reference, both live and video. http: //www. youtube. com/watch? v=Xb. GVBV 3 -F 48 The motion of the water balloon is different with every take, yet has a consistent feel.

Elements of a Water Balloon Drop Let’s look more carefully at the physics in each element of a water balloon drop. Initial Drop Bounce Squash Settle

Part 1: The Initial Drop The initial part of the water balloon drop is similar to other drop tests yet the fluid nature of the balloon adds new elements. Initial Drop

Incompressibility Most solids and liquids are almost incompressible; it takes enormous force to change their volume. Elastic materials may stretch easily but their volume stays constant.

Young’s Modulus (Stiffness) Young’s modulus indicates amount of force required to compress or expand a material. Material Young’s Modulus (GPa) Rubber 0. 01 to 0. 1 Water 7 Wood 9 to 11 Concrete 30 Steel 200 Rubber is compressible but water is almost as incompressible as wood!

Demo: Incompressibility of Water Place a brick on top of a syringe filled with air. Air compresses (a bit). Place a brick on top of a syringe filled with water. Water doesn’t compress.

Pressure and Force Pressure is defined as Pressure = ( Force ) ( Surface Area ) If you weigh 200 pounds and the surface area of the soles of your shoes is 100 square inches (10”x 10”) then your weight exerts a pressure of 2 pounds per square inch on the floor.

Demo: Bed of Nails My weight is almost 200 pounds and the surface area of my butt is about 200 square inches. Pressure on the bed is about 1 pound per square inch and there’s about one nail per square inch. Need about 5 pounds per nail to pierce the skin. Warning: Never jump into bed (of nails).

Quiz Question Glue bricks together into various shapes. Which exerts the most pressure on the table? D A B C E : Pressure is the same for all 4 cases

Quiz Question D exerts more pressure than A (more weight). D exerts more pressure than B (less area). C exerts the same pressure as A. D A B C E : Pressure is the same for all 4 cases

Pressure in Liquids Pressure in a liquid depends on depth. As with a stack of bricks, weight of what’s above determines pressure. Low Medium High

Water Balloon at Rest Water pressure pushes on the rubber, stretching it into a flattened shape. Low Water Pressure Medium High Tension of the rubber also affects the shape.

Repose Angle and Contact Angle Water balloon has a repose angle and contact angle that depend on the rubber’s stiffness. Repose Stiff Flaccid Contact Beads of liquid have similar shapes, depending on surface tension. Mercury Water

Quiz Question A can full of water has holes in the sides through which water comes out. What happens when you drop the can? A) The water continues to spurt out in the same way as the can falls. B) The water spurts out faster as the can gains speed. C) The water stops coming out the holes as the can falls.

Demo: Pressure & Weight C) The water stops coming out the holes as the can falls. The can is in weightless freefall. Flow stops since the pressure is due to the water’s weight.

Falling Water Balloon Slides off and falls Because free fall is a weightless state, the water balloon will be roughly spherical as it falls. Faucet drip May have some initial vibrations depending on how it is released.

Part 2: Squash on Impact The fluid nature of the balloon makes the squash on impact very pronounced. Squash http: //www. youtube. com/watch? v=UMe. J 4 Zf. Rd 3 w

Force of Impact for Squash To understand the force of impact you need to understand how forces relate to momentum. http: //www. youtube. com/watch? v=-p 5 zoufj. Owc

Momentum of an object depends on: * Velocity of the object * Weight of the object Bullet Rugby Player

Momentum and Force To stop an object with a large momentum requires either: • Large force (stopping the object quickly). • Small force applied for a long time. Notice that changing object’s momentum depends on force and time interval.

Demo: Egg Throw a raw egg as fast as possible at a bed sheet that’s held loosely. X X X (Hold here)

Egg Throw Analyzed Throw egg at sheet or wall with same speed. Change in momentum is the same (egg is stopped). Which case has: Largest time of impact? Throw at the sheet. Largest force on the egg? Throw at the wall. LONG TIME small force short time LARGE FORCE

Automobile Safety Maximizing time of impact on the driver minimizes the force of impact. This principle used in design of: Seatbelts Air Bags Crumple Zones

Demo: Vampire Stake Place a very heavy stake on my chest and strike with a hammer. Why am I not killed?

Demo: Vampire Stake Ouch! X X Soft Flesh Quick stop, Large force (FORCE) x (time) Slow stop, Small force (force) x (TIME) Not safe if stake strikes hard skull Quick stop, Large force (FORCE) x (time)

Quiz Question Ironman falls off the roof of a 10 story building and lands on the sidewalk. Even though he is an ordinary man, he’s unhurt as long as his metal suit is undamaged and intact. Is this physically realistic? A) Yes or B) No

Ironman B) No The suit does not increase the time of impact so the force of impact is the same. The suit is no safer than being inside of a falling safe.

Next Lecture More Squash & Stretch Homework #6 Stop-motion Animation of Falling Due Tuesday, Sept. 25 th (Next week) Remember to turn off your clicker