Upcoming Deadlines Eighth homework Reverse Video Reference of Walking Due Thursday, Oct. 27 (this...

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Uniform Motion

Upcoming DeadlinesEighth homework Reverse Video Reference of WalkingDue Thursday, Oct. 27 (this week)20 points (10 points if late)

For full schedule, visit course website:ArtPhysics123.pbworks.comPick up a clicker, find the right channel, and enter Student ID1Homework #8Reverse video reference of walking

Normally, animators shoot video and use it as reference for their work. In this assignment, you will do the reverse. Specifically, you will watch each of three animation clips and shoot video in which you recreate them as accurately as possible. 2Homework #8Watch each of the three video clips on the assignment pageFilm yourself acting out each scene, each in a separate clip. Reproduce the motion of the character as accurately as possible - you will be graded on how well you do this. Dont just quickly act it out. Study each clip carefully to capture all of the motion details. Pay attention to staging, camera angle, camera moves (if any), etc. Post all three videos in a blog entry entitled Reverse Video Reference of Walking 3Homework #8Assignment is due by 8AM on Thursday, Oct. 27th20 points (10 points if late)

4Survey QuestionUp to now, roughly how many hours per week do you spend this class (outside of attending class):A) An hour or less per weekB) About two hours per weekC) Four hours, on averageD) Six hours a week, more or lessE) Well over 6 hours per week


Review QuestionMr. A pushes way from Mr. B while Mr. B just holds his hand rigidly in place.Which of them has the largest acceleration?

Mr. ApushesMr. B holdsMr. AMr. BThey have the same acceleration

6Review QuestionObject AObject BActionReactionAccelerationsMr. A has the larger acceleration.If A pushes B then both accelerate by equal forces.By Law of Acceleration, Object A, having less mass, will accelerate more than the heavier Object B.7Wile E. Coyote, Propelled

Which of these devices would actually work to propel Wile E. Coyote?

Outboard motor in a tub of water.Big fan blowing a large sail.Both would work.Neither would work.A)B)8Internal Propulsion

Air pushes sailSail pushes airPropeller pushes airAir pushes propellerAction/Reaction PairsInternal propulsion is not possible because the impulse gained from one reaction is lost due to another internal action.Back of the tub acts like the sail.

This would work!9Jumps


JumpingJumping is a basic character animation exercise that incorporates many of the basic elements found in drop tests for inanimate objects.By Danielle Domurat

http://www.youtube.com/watch?v=jwerYsdE9XsBy Carlos Nunezhttp://www.youtube.com/watch?v=XWheRtQkC9o11

X = Center of GravityXXCrouchTake-offApexJump HeightJump TimeThe simplest part of a jump is the time in the air and how it is related to the height of the jump.Timing the Jump12Jump Time & HeightJump Time (seconds)FramesJump Height1/2411/3 inch1/1221 1/3 inches1/833 inches1/645 1/3 inches 612 inches1/3821 inches 124 feet2/3167 feet 189 feet12416 feetThe same table we saw for the ball drop gives the jump time (from take-off to apex) and jump height.The formula to compute this table is:(Distance in inches) = (Number of Frames) x (Number of Frames) x (1/3 inch)13

Jump Time Example

X = Center of GravityXXXTake-offApexLanding21 inches8 frames8 framesFor a jump time of 8 frames, the jump height is 21 inchesHang time = 2x(Jump time)14

Crouching Tiger, Hidden Dragon (2000)

Characters stay in the air an unrealistically long time, even considering the impressive height of their jumps.http://www.youtube.com/watch?v=xxCvv3bDyvw15

XX = Center of GravityXXCrouchTake-offApexPush HeightJump HeightJump TimePush TimeYou can time the push (from crouch to take-off) using a simple formulaTiming the Push16

Jump Magnification Jump Magnification = Jump HeightPush Height Jump Magnification = 2 Jump Magnification = 8Timing of the push depends on the jump magnification.17

Formula for Timing the PushCan use this formula to check the timing of the push depending on the timing of the jump.Push Time = Jump Time Jump Magnification18

Timing the Push Example

XX = Center of GravityXXXCrouchTake-offApexLanding10 inches21 inches8 frames8 frames4 framesJump magnification = 2so push time is half aslong as the jump time.19Planning a JumpPick the desired jump time or jump height.Use the table to find the jump height given the jump time (or vice versa).Pick the desired push height for the crouchDetermine the push time from the jump magnification.

Animators can plan out a realistic jump by these steps:20A Big Jump

ApexA character jumps 16 feet into the air. From the table, thats a jump time of 24 frames (take-off to apex). The push height is 16 inches; what is the push time?Push Time = Jump Time Jump MagnificationTwo framesFour framesSix framesEight framesTwelve framesJump Height = 16 feetPush Height = 16 inchesJump Time = 24 frames

21A Big Jump

ApexPush Time = Jump Time Jump MagnificationJump Height = 16 feetPush Height = 16 inchesJump Time = 24 framesTwo framesJump magnification is 12 (=16 feet/16 inches)

Push time is (24 frames)/12 = 2 frames22Push FactorJump Magnification = (Push Factor) x (Push Height in Feet)Push Time (in frames)Push Factor136293442 1/46189/16Push Factor = 36 / (Push Time in Frames)2

Can calculate jump magnification with this:23The Incredible HulkThe Incredible Hulk is big, lets say 10 feet tall.Say his push height when he jumps is 3 feet.If you animate 2 frames from crouch to take-off, how high does he jump?For a push time of 2 frames the push factor = 9 so the jump multiplier is

(Jump multiplier) = (9) x (3) = 27 (Push Factor) x (Push Height)

He jumps 81 feet into the air since his push height of 3 feet gets magnified by a factor of 27 (the jump multiplier).

Jumps about 8x his height24

The Hulk (2003)http://www.youtube.com/watch?v=5JsDylEPNh0The enormous jumps by the Hulk look fake because, for such huge jump magnifications, the push time would be less than one frame.25Boundin (2003)Big jump magnifications and jump times give a feeling of lightness and happiness in a cartoon.http://www.youtube.com/watch?v=CDtiZImH0qI

26Timing the Landing

If the crouch on landing is similar to the crouch when pushing off then the landing has similar timing to the take-off.If the crouch on landing is shorter then the timing of the landing is shorter; if the crouch is longer, the timing is longer.27

Forces when JumpingThe three main forces on a person jumping are:Gravity (Downward)Support of the floor (Upward)Frictional force of the floor (Horizontal)Only these forces can accelerate the person.Gravity is constant but the force exerted by the floor can increase in reaction to the action of the person exerting a force on the floor.

28Jumping is done by pushing downward on the ground (action) so the ground pushes upward on you (reaction).How high you jump depends on the force and on the distance over which you apply that force.

Can only push while in contact with the ground so squatting helps by increasing distance.Jumping Action/ReactionActionReaction29You can determine the average force exerted when jumping as:

(Jump Force) = (Jumpers Weight)x (Jump Magnification)

Remember that

Average Push ForceJump Force(Action) Jump Magnification = Jump HeightPush Height30The Incredible HulkIf The Hulk has a push height of 3 feet and he makes a huge jump, rising a height of 300 feet, how much force does he push with?

Jump magnification is 100 so the push force is 100 times his weight. The Hulk is twice as tall as a normal person so his weight is at least 8 times larger (probably closer to 10-12 times larger). So if The Hulk weighs 2000 lbs, hes pushing off with 200,000 lbs of force (200 tons).31Action/Reaction Jumping Forward

ActionReactionTo jump upward and also forward, the action force (pushing downward with your legs) needs to also be pushing towards your back so that reaction force of the floor is upward and forward.Jumping forward at a 45 requires almost 50% more pushing force to reach the same vertical height.32Forces when Landing

If the timing of the landing is similar to the timing of the take-off then the forces on landing are similar to the forces on take off.

If the landing has quicker timing then the forces are proportionally larger on the landing.

If the landing has slower timing than the take-off then the landing forces are smaller.ActionReaction33Hancock (2008)One of the few things in this movie thats physically accurate is that the force exerted on the ground is just as extreme on the take-off as it is on the landing.Take-offLanding

34Overlapping ActionOverlapping action is all the secondary motions that occur in addition to the primary motion.

In this example the primary motion is the jump itself.Motion of the arms and head are active secondary motions, created by the character, while the drag of the clothing, hair, etc. are passive secondary motions.35

Secondary ActionSecondary actions are a part of acting. They are the extra actions that actors (and animators) use to convey personality or mood.For example, in this scene Hogarth is playing with the telephone cord to convey that he is bored and knows exactly what his mother is going to tell him to do.

Clickhttp://www.synchrolux.com/?p=27336Timing of Overlapping ActionsOverlapping actions may or may not have timing that matches that of the primary motion.

Passive secondary motion, like follow-through and drag, is more likely to be synchronized with the primary motion but sometimes active secondary motion is also synchronized, in support of the primary motion.37

Swinging A