1. Upcoming Deadlines Ninth Homework (Stop-motion Character Animation) Due by 8am on Tuesday, April 10 th (Next week) 20 points (10 points if late) Tenth Homework (Outline for Second Term Paper) Due by 8am on Tuesday, April 17 th (In 2 weeks) 20 points (10 points if late) For full schedule, visit course website: ArtPhysics123.pbworks.com Pick up a clicker, find the right channel, and enter Student ID

2. Homework Assignment #9 In this assignment you will create a simple stop-motion animation of a moving character. Grade based primarily on how successful you are in making the character’s motion believable, with correct timing, sense of weight, overlapping action, etc.

3. Homework Assignment #9 Post your animation clip to your blog in an entry entitled "Stop-Motion Character Animation.“ Assignment is due by 8am on Tuesday, April 10th 20 points (if late, 10 points) The top three clips in the class, as selected by another celebrity judge, will receive a bonus of 20 extra points.

4. Special Guest Animation Judge The top three stop-motion character animations (next Wednesday’s homework) will be picked by Jason Spencer Galsworthy of Dreamworks Animation (and formerly with Aardman Animation).

5. Survey Question For your stop-motion character animation you’re planning to: A)Do it by yourself B)Do it as a two-person team C)Do it as part of a team of three or more persons

6. Review Question If a small child and an adult lose balance at the same time, which one hits the ground first? A)Child B)Adult C)Almost the same for the two

7. Tripping and Falling Axis of Rotation X CG A) The child hits the ground first. Can view this two ways: *Child has small rotational inertia so rotates faster. *Child’s center of gravity is initially closer to the ground so not as far to fall.

8. Review Question To do a pirouette turn you get more torque if you push with: A)Your feet together B)Your feet apart C)Position of your feet doesn’t matter, just the amount of force Feet apart Feet together

9. Review Question B) Your feet apart The farther the distance between the feet, the greater the lever arm so the greater the torque for creating the rotation. Push on Floor Reaction Force Lever Arm Feet apart (Easy) Feet together (Harder)

10. Joints & Levers (cont.)

11. Mechanical Lever Lever converts an effort force into a load force by ratio of distances from fulcrum. Push down with a small effort force over a large distance Lift a large load weight over a small distance Axis of rotation goes through the fulcrum point. Fulcrum

12. First Class Levers Fulcrum Effort Arm Load Arm Lift a heavy load using small effort by having a long effort arm and/or short load arm. First Class Lever: Fulcrum is located between the input force (effort) and output force (load).

13. Efficiency vs. Speed Effort Load Fulcrum Effort Load Fulcrum Efficient but slow Inefficient but fast

14. Examples of First Class Levers Crowbar Scissors Effort Load Fulcrum Crowbar and scissors are efficient (big load force) but slow (long effort distance). Load Effort

15. Examples of First Class Levers A trebuchet is inefficient but fast. Load Fulcrum Effort

16. Second Class Levers Lift a heavy load using small effort by having a long effort arm and/or short load arm. Second Class Lever: Load is located in between the effort force and the fulcrum. Effort Arm Load Arm Fulcrum Load Effort

17. Examples of Second Class Levers Wheel Barrow Effort Load Fulcrum Hole Punch Second class levers are always efficient and slow.

18. Third Class Levers Third Class Lever: Effort force is located in between the load and the fulcrum. Effort Arm Load Arm Third class levers are always inefficient but fast (since load arm is longer than effort arm). Load Effort

19. Examples of Third Class Levers Effort Load Fulcrum Broom Jaw Load Effort

20. Human Arm as a Lever Biceps muscle exerts effort force close to your elbow (fulcrum) to raise your forearm (load). This is what type of lever? A)First class B)Second class C)Third class

21. Human Arm as a Lever Biceps is a third class lever so a large effort force acts over a small distance to move a small load over a large distance. Triceps is also a third class lever, which pulls the arm in the opposite direction. Because muscles can only contract, they’re almost always found in pairs, like biceps/triceps. Effort Load

22. Human Foot as a Lever Effort Load Fulcrum To lift the body on the toes, the gastrocnemius (one of the strongest muscles in the body) contracts, lifting the heel upward. This is an example of a second class lever. Raising heel, as in walking.

23. Weight Shift More Effort Load Fulcrum Weight shift forward shortens the load arm, reducing the required effort to lift the heel. Less Effort Load Fulcrum Line of Gravity

24. Human Neck as a Lever Load Fulcrum In general, the levers in animals’ bodies sacrifice efficiency for speed and to keep a compact body form. The neck muscles are the body’s only first class lever This lever is not efficient since the effort arm is shorter than the load arm. Effort

25. Creating Scale

26. Making it Big (or Small) What makes these machines seem monstrously big? What makes these dragons seem curiously small?

27. Relative Size Using objects of known size is the most common way to show scale. How big is this dragon? The humans give the scale for the size of the dragon.

28. Size and Distance This image uses distance cues, such as linear perspective and atmospheric perspective, plus known size (GG bridge), to establish scale.

29. Visual Contrast Relative size needs visual contrast Football players appear as normal size on playing field … but are giants in contrast with an average person.

30. Conflicting Visual Cues Relative size and perceived distance are easily confused by conflicting visual cues, as in forced perspective. Ames room

31. Ambiguous Relative Size Relative size cannot create scale when visual cues are ambiguous, as in fantasy worlds. Giant elephant or tiny soldier? Is Alice a giant or is it a tiny door?

32. Staying on Model A character’s scale needs to stay consistent, not just in its visual proportions but also in its physical attributes and in all aspects of its animated motion.

33. Physical Cues for Size There are many physical “cues” indicating the size of an object or a character. Some physical cues are simple, such as a short pendulum swings faster than a long one. Some physical cues are subtle, such as small animals having a faster heart rate.

34. Heart Rate versus Size 1 ounce 1 lb 100 lb 10,000 lb 1000 100 10 Beats per minute Strong correlation between heart rate and animal size is predicted by physics

35. Defining Size Various ways to define size, such as volume, weight, etc. For simplicity, we’ll use length (or height). 2 ft. 6 ft. For example, Charming is 3x the size of Puss.

36. Gravity Timing Timing of motion due to gravity is a physical cue for size. For constant acceleration, the distance travelled goes as the square of the time elapsed. Baseball falls for 3 frames Bowling ball falls for 6 frames Bowling ball is x4 size of baseball and takes x2 time to fall comparable distance (one diameter).

37. Scale Models Independence Day (1996) Earth vs. the Flying Saucers (1956) Scale models filmed at x5 normal will appear to be x25 times larger when they are destroyed by impact or explosion. Apparent size goes as the square of the timing.

38. Timing and Scale Notice that the timing of a small marble falling in slow-motion is similar to that of a large bowling ball falling in real time. 120 fps30 fps http://www.youtube.com/watch?v=AmBVX7sSN2w http://www.youtube.com/watch?v=fOHZJ5gp5Mg

39. Jason & the Argonauts (1963) Compare the sense of scale when running this scene at different playback speeds. http://www.youtube.com/watch?v=vGhnx_9z-zo

40. Swinging and Tipping Timing of motion for swinging or tipping over, is also a physical cue for size. Man is 4x height of baby so he falls for 2x the time Timing scales with acceleration of gravity

41. Cadence Timing of swinging pendulum is also gravity timing Cadence (steps per minute) is a physical cue of size. Pendulum x4 longer swings in x2 the time regardless of angle. x1 Time x2 The slow, lumbering walk makes AT-AT feel huge.

42. Escaping from a Giant If a giant walks with a gait that matches his size, would you walk at a faster speed than the giant? No. For example, if the giant is 25 times your height then although his steps take 5 times longer, with each step he goes 25 times farther so his walking speed is x5 faster than your walking speed. Run! Jason and the Argonauts

43. Walking Speed Walking speed is a physical cue for size. Long legs swing more slowly than short legs but also have a longer step length. Legs x4 longer have x2 walking speed since x4 step length. x1 Distance x4 Time x2

44. Empire Strikes Back (1980) http://www.youtube.com/watch?v=JhpS69eAXrU Notice the timing of the giant walking tanks.

45. Empire Strikes Back (1980) http://www.youtube.com/watch?v=JhpS69eAXrU In this same scene we see a two-legged walker (AT-ST) in the background. Just from the timing of its walk we know it’s approximate size.

46. Size, Area, and Volume Big cube is 3x the size so it has 9x the area and 27x the volume. Proportions of area and volume apply to any shape. For example, to make this flower pot 3x bigger takes 9x more paint and 27x more clay.

47. Body Weight 6 ft; 180 lb 2 ft; 7 lb 18 ft; 4900 lb Body weight is a physical cue for size. When size x3, body weight x27 Weight scales with volume

48. Muscle and Bone Strength Muscle and bone strength are physical cues for size. When size x3, strength x9 Strength scales with cross-sectional area x9 x1 x3 x1

49. Weightlifting Lifts 90 lb; 50% of body weight Lifts 10 lb; 150% of body weight Lifts 810 lb; 17% of body weight Weightlifting (relative to body weight) is a physical cue for size. Muscle force scales as area while body weight scales as volume. 2 ft, 7 lb6 ft, 180 lb18 ft, 4900 lb

50. Skeletal Fraction Skeletal fraction is a physical cue for size. RabbitElephant Skeleton is 9% of total weight for rabbit and 27% for elephant (their size ratio is 15-to-1) Bone strength scales as area while body weight scales as volume. Thin bones Thick bones

51. Posture Elephant Posture is a physical cue for size. Large animals need to stand straight so as to minimize strain on bones due to weight. Horse Cat Rabbit Posture, measured as mechanical advantage of limbs, scales as size

52. Bending Strength Bending strength is a physical cue for size. Strength goes as area; weight goes as volume. Large beams bend more, relative to their size, while small beams are relatively stiff. Galileo pointed out this scaling law for beams.

53. Relative Stiffness Relative stiffness is a physical cue for size. Stiffness goes as area; weight goes as volume. Thread, string, and rope differ by about x4 in size (length and diameter) and they are made of similar materials. ThreadStringRope

54. Burning and Dissolving The time it takes to burn or to dissolve is a physical cue for size. Burn or dissolve rate goes as area but total amount goes as volume. Kindling is consumed quickly while large logs take longer to burn. Cubes dissolve slower than grains.

55. Internal Organs Complexity of internal organs, such as lungs and intestines, is a physical cue for animal size. Absorption amount goes as area while consumed amount goes as volume Earthworm Rabbit Horse

56. Eating Food consumption per pound of body weight is a physical cue for animal size. Caloric energy required goes as area while body weight scales as volume Mouse 28% Squirrel 18% Leopard 5% Zebra 2%

57. Heart Rate Oxygen required goes as area while heart size scales as volume. Heart rate is a physical cue for animal size. Mouse: 630 b.p.m Cat: 150 b.p.m Donkey: 37 beats per min. Smaller animals tend to be frisky due to faster “clock rate.”

58. Longevity Total heartbeats per lifetime is about one billion. Longevity is a physical cue for animal size. Mouse: 3 years Cat: 10 years Human longevity is roughly 30 years, without medicine. Donkey: 40 years

59. Fur Furriness is a physical cue for size. Small animals have trouble staying warm while large animals have trouble staying cool. Mice huddled for warmth Large ears vent heat Heat production goes as volume while heat loss goes as surface area.

60. Climate Climate is a physical cue for size. Small mammals thrive in warm climates; the Arctic has mostly large mammals. Etruscan pygmy shrew Polar bear Smallest mammal Largest land carnivore Heat production goes as volume while heat loss goes as surface area.

61. The Croods (2013) The Croods is one of Dreamworks’ upcoming films and one that features creatures of all different scales. The animation team, headed by James Baxter, is keenly aware of the challenges of creating scale.

62. Next Lecture Waves, Part I Homework 9 (Character Animation) Due Tuesday, April 10 th (Next week) Please turn off and return the clickers!