Upcoming Deadlines

1. Pick up a clicker, find the right channel, and enter Student ID Upcoming Deadlines Fifth Homework (Video Analysis of a Jump) Due Wednesday, Feb. 24th (Next week) 15 points (10 points if late) Sixth Homework (Stop-motion Animation) Due Wednesday, March 3rd (In two 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

2. Activating your Clicker * Turn on your clicker. * Enter the channel number or letter for joining this class. Hit Enter/Send key. * Clicker should read AP123S258 * 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.

3. Extra Credit Opportunity Go to any event at Cinequest Film Festival in downtown San Jose. Turn in proof of attendance (receipt, photos, etc.) for 5 points of extra credit.

4. Extra Credit Opportunity Attend the Game Developer’s Conference in San Francisco, on Saturday, March 13th Student registration is $75 (ouch) Turn in your receipt for 10 points of extra credit. For info: www.gdconf.com

5. 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.

6. Homework Assignment #5 Original Video Reference

7. Homework Assignment #5 Import 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".

8. Homework Assignment #5 Straight Line Parabolic Path of Action Parabolic Curve

9. Homework Assignment #5 Finally, rewind your video to the first frame of your jump and from the "File" menu select "Record -> Quicktime Movie". Hit the play button and allow the clip to play until the end of your jump. Next, in the "Capturing Quicktime MOV" window click "Save As" to save the recording.

10. Homework Assignment #5 Video Reference with Tracking

11. Homework Assignment #5 Check that your saved Quicktime 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 Wednesday, Feb. 24th (week from today). 15 points (10 points if late)

12. Survey Question • So far the pace of the class has been: • Too fast • A little fast • About right • A little slow • Too slow

13. Review Question The motion graph for a ball drop, going from the apex until the ball just touches the ground, looks like: A) B) C) D)

14. Motion Graph of a Ball Drop D) Height Frames

15. Arcs in Animation

16. 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. • Squash & Stretch • 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

17. 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. We have already discussed several of these principles of animation, specifically: • Squash & Stretch • 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

18. 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. Today we will discuss arcs and how they relate to animated motion. • Squash & Stretch • 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

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

20. Importance of Arcs Disney animation legends Frank Thomas and Olie Johnston write: 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. Right Wrong

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

22. Speed in Circular Motion Rotational Speed: Revolutions per second Tangential Speed: Total distance per second Same Rotational Speed Different Tangential Speeds

23. Throwing Arm The longer the throwing arm, the greater the tangential speed so the farther it can throw. Tangential Speed x2 Sling lengthens the arm at almost no cost in the weight. Doubling the speedquadruples the range!

24. Timing on Circular Arcs A circular arc is a simple path of action but the timing may be complex and textured. • 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 Slow in Uniform Slow out

25. Non-Uniform Circular Motion Two 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

26. Tipping Over Tipping over is a common example of motion on a circular arc. Two ways to tip over: X X Center tipped past point of contact Center past an edge

27. Tipping Rotation A brick rotates about a point as it tips;that point is the center of a circular arc. X X X X Friction tends to keep the brick from sliding until it loses contact with the table.

28. Exponential Spacing 1 Constant acceleration (Odd Rule) 1 3 Release 2 5 3 7 1 4 Release 2 3 Exponential Spacing 4 As the slope of the incline increases, the acceleration itself accelerates.

29. Rolling off a Tipping Point 3 2 4 1 5 6 7 Peak 8 Slowing out from a tipping point is very slow initially, but then accelerates rapidly.

30. Video Reference of Tipping Brick http://www.youtube.com/watch?v=otYAYMZ4iGg

31. Anticipation & Exponential Spacing Also notice motion blur near top of brick, which has large tangential speed. Texture of the timing as the brick tips over creates anticipation, which you want at the start of a scene

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

33. 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.

34. Pencil Test Example http://www.youtube.com/watch?v=xuoJdNGxffU

35. Motion Graph for Pendulum The motion graph (angle vs. frame) shows that the timing is mostly textured (curves the most) at the apexes. #7 SLOW, again #1 Angle SLOW SLOW, again FAST FAST #4 Ball goes fastest around the bottom but the speed is almost constant. SLOW Frame

36. Uniform Rotation in Perspective The 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.

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

38. 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

39. Who Framed Roger Rabbit? (1988) http://www.youtube.com/watch?v=sLNqtU-gYPc

40. Demo: Don’t Flinch Pendulum swings back and forth yet it doesn’t hit your face.

41. Bowling Ball Pendulum http://www.youtube.com/watch?v=UNsD15GjWWE Click This video clip lets you experience what it’s like to do this demo.

42. Spirals A spiral is just a circular arc with a radius that’s either increasing (spiral out) or decreasing (spiral in). Concept art fromPirates of the Caribbean 3

43. Rotational Speed in Spirals If the radius decreases without pulling the object inward then the rotational speed increases (due to shrinking radius) but the tangential speed stays constant. Spacings along the curve stay constant. Spiral In

44. Demo: Interrupted Pendulum An “interrupt” bar changes the radius of the arc for a pendulum. Tangential speed does not increase due to the pendulum whipping around the interrupt bar. Energy is not increased by the interrupt bar so ball swings back to the same spot. Bar

45. Rotation in Spirals (cont.) If the radius decreases by pulling the object inward then the rotational speed increases due to shrinking radius and due to an increase in the tangential speed. Spacings along the curve get bigger and bigger. Spiral In

46. Demo: Skater’s Spin FAST Rotation Slow Rotation Exert a force to pull hand weights toward my body, causing a big increase in rotational and tangential speeds

47. Rotation in Spirals (cont.) If the tangential speed decreases (say by friction) but inward force constant then the rotational speed still increases. Spacings along the curve get shorter yet itstillspinsfasterand faster. Spiral In Coin Vortex

48. Rotation in a Spirals In summary, typically as an object rotates in a spiral, the rotation speed increases as the radius decreases. So as radius goes down, the r.p.m.s go up. However the spacings may get longer, or shorter, or stay constant!

49. How Does the Brick Fall? 1 Does the brick rotate and then fall down the side of the table? X X 2 X 3 No! The brick does not fall this way. X 4

50. Video Reference of Tipping Brick http://www.youtube.com/watch?v=otYAYMZ4iGg