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Homework #9 – Stop-motion character AnimationDue Thursday, November 10th (Next Thursday)20 points (10 points if late); 20 point bonus to top 3
For full schedule, visit course website:ArtPhysics123.pbworks.com
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Homework Assignment #9In this assignment you will
create a simple stop-motion animation of a moving character.
For your character, use a doll or stuffed animal that's easily posed.
You may even use an inanimate object, such as a table lamp, as long as you can animate it so that it looks like a character.
Homework Assignment #9
http://www.youtube.com/watch?v=EiEVdTQGGTM
Homework Assignment #9Your animation should be composed of at least a
dozen different images but you can use the same photo in two or more frames to get timing right.
Try to make the motion of the character as realistic as possible so that your audience will momentarily forget that it's not actually alive.
In homework assignment #6 you created a stop-motion animation of an inanimate falling object; if you're not happy with how you produced your earlier animation then re-read that assignment for alternative ways of creating stop-motion.
Homework Assignment #9You may work together with one or more
classmates to create a single animation for the team.
Clearly indicate the work done by each person, for example if different persons animate different characters or different scenes.
More is expected from a team effort; an animation created by a three person team should present three times as much work as a solo effort.
Homework Assignment #9Post your animation clip to your blog in an entry
entitled "Stop-Motion Character Animation.“ Assignment due 8am on Thur., November
10th
20 points (if late, 10 points)The top three clips in the class, as selected by a
celebrity judge, will receive a bonus of 20 extra points.
Extra Credit Opportunities• Attend the Star Party this Saturday. Telescope viewing,
talks and hands-on activities on Tower Lawn and Science 142
• Attend the “Technology of Animation” event, featuring guest speaker Jeffery Katzenberg, at the computer history museum in Mountain View. Registration is at the bottom. http://www.computerhistory.org/events/#technology-animation
• Attend any event at the San Francisco International Animation Festival (November 10-13).
Present proof of your attendance to any of these (receipt, photos, etc.) for 10 points of extra credit.
Survey Question
Writing the term paper was:A) Rather enjoyable B) Somewhat enjoyableC) OK D) Somewhat painfulE) Rather painful
Survey QuestionFor Dr. Kaufman, do you think
reading the term papers was:A)Rather enjoyable B)Somewhat enjoyableC)OK D)Somewhat painfulE)Rather painful
Review QuestionAt which position do you exert the least weight on the ground?
A) StrideB) SquashC) Passing
PositionD)StretchE) Same weight
at all timesStride Stride StrideP.P.P.P.
Squash SquashStretch Stretch
Force Plate Experiments
C) Passing Position
Can measure weight shift during walk cycle using force plates.
Body Weight
Stretch
PassingPosition
PassingPosition
Squash Stretch
Stride
Squash
Upward centrifugal force due to your motion lightens your weight.
Review QuestionCompared with the walking speed of a 6 foot man, the walking speed of a 150 foot giant is…A) 25 times
slowerB) 5 times slowerC) About the
sameD)5 time fasterE) 25 times
fasterthan the man. Jason and the Argonauts
Stride Time and Stride Length
Stride Time
Stride Length
Speed
x 2 x 4 x 2x 3 x 9 x 3x 4 x 16 x 4x 5 x 25 x 5x 10 x 100 x 10
The giant is x25 taller so each giant stride is x25 longer (in distance).
But the stride time for the giant is x5 more than the man’s stride.
So the giant’s speed is x5 faster than the man.
D) 5 times faster
Speed = ------------ TimeDistance
Jason and the Argonauts (1963)
http://www.youtube.com/watch?v=2BaLKYlC07w
Notice how the timing of the giant’s walking gives the sense of his massive scale.
Although the gait his lumbering, the giant easily catches the running men.
WalksPart II
Ray HarryhausenRay Harryhausen, the master of stop-motion animation, created the special effects in many films from the 1940’s to the 1970’s
One of his best scenes in the skeleton battle in Jason and the Argonauts
Skeleton Battle Scenehttp://www.youtube.com/watch?v=0gKD7qy98-E
Notice how the animated skeletons walk (conveniently, we see their pelvis and leg bones).
Energy and Walking
We’re inherently lazy so many actions that we perform unconsciously while walking reduce energy expenditure.
So far we’ve examined walking from the point of view of forces.
An alternative approach is toexamine theenergy expendedin walking.
Home Demo: Silly WalksTry walking around as John Cleese, who is the Minister of Silly Walks.
You will find that you use much more energy than normal walking.
http://www.youtube.com/watch?v=IqhlQfXUk7w
Energy Budget (Inanimate)Moving objects have an energy budget.For inanimate objects, this budget is:
Kinetic Energy (K) – Energy due to their speedPotential Energy (P) – Energy due to their heightFriction Loss (F) – Energy lost due to friction forces
K = 0P = 100F = 0
K = 20P = 70F = 10
K = 40P = 40F = 20
Total Energy = 100
Demo: Ball RacesMarbles start at equal height and race on
these rail tracks (almost no friction).Track B has a long dip in the center.
Winner? A) Ball A; B) Ball B; C) Near perfect tie.Hint: Kinetic energy + Potential energy stays constant.
Demo: Ball RacesB) Ball B is the winner.
K = 0P = 100F = 0
K = 50P = 50F = 0
K = 50P = 50F = 0
K = 50P = 50F = 0
K = 50P = 50F = 0
K = 100P = 0F = 0
K = 50P = 50F = 0
Ball B has a high speed in the center section.
Energy and Wile E. Coyote
The energy budget here is wrong because the rock, after rolling down hill, flies back up to a point higher than from where it started!
From Going, Going, Goshhttp://www.youtube.com/watch?v=h2j_n0sRXeU
Energy Budget, BouncingK = 45P = 5F = 0
K = 50P = 0F = 0
K = 36P = 4F = 10
Kinetic EnergyPotential EnergyFriction Losses
Total Energy = 50
Energy Budget, Sack DropK = 0P = 200F = 0
K = 0P = 0F = 200
K = ???P = 100F = 5
Kinetic EnergyPotential EnergyFriction Losses
Flour sack sitting on a shelf starts with potential energy.
After it settles, all the energy is lost to friction forces.
What is the kinetic energy when fallen half-way down?
A) ZeroB) 200C) 100D) 95E) 105
(Air resistance)
Energy Budget, Sack DropK = 0P = 200F = 0
K = 0P = 0F = 200
K = 95P = 100F = 5
Kinetic EnergyPotential EnergyFriction Losses
D) 95
The total budget (K+P+F) has to equal 200.If there was no air resistance then the falling speed would be greater and K=100.
With more air resistance, the friction loss would be greater and kinetic energy less.
(Air resistance)
Energy Budget (Animate)Animate objects can increase their
energy budget by doing work.Work Input (W) –
Energy added by doing work.K = 0P = 0F = 0W = +0
Kinetic EnergyPotential EnergyFriction LossesWork Input
K = 100P = 0F = 10W = +110
K = 300P = 0F = 20W = +320
Energy Budget in Jumping
K = 0P = 50F = 0W = 0
K = 200P = 100F = 50W = +350
K = 120P = 175F = 55W = +350
K = 90P = 200F = 60W = +350Leg muscles
do work as you push off when jumping.
Slow down as you rise to apex so kinetic energy (K) goes down.
Most of the friction loss is during push but a little loss due to air resistance.
Energy Budget in WalkingK = 100P = 100F = 60W = +60
K = 100P = 100F = 0W = +0
Walking takes work due to all the frictional losses.
Simplified Walking ModelPelvis is a double-forked bar with spherical hip joints. Legs are straight bars without knees, ankles, or feet.
Center of gravity rises and falls as an inverted pendulum.
CG
CG
Passing Position
Passing Position
Stride
Stride
Passing Position
Walking Forward
We have to do work to raise the CG and much of that energy (30-40%) is lost to friction.
Simplified Walking Model
Pelvic RotationAs the passing leg swings forward, the hips swing around, rotating about the planted leg.
WithoutRotation
WithRotation
Pelvic Rotation
Pelvic Rotation & Center of GravityPelvic rotation keeps the center of gravity from dropping as far during the stride (keeping step length the same).
CGStride
Passing Position
Passing Position
Passing Position
Stride
CG
Walking is more efficient with pelvic rotation.
Path of Action ofCG with Rotation
Without Rotation
Walking Fo
rward
Pelvic ListIn the passing position the pelvis drops slightly on the non-weight bearing side. This motion is called “pelvic list.”
Note that the knee has to bend to lift the foot, otherwise it would drag the ground.
Pelvic List
Pelvic List & Center of GravityPelvic list keeps the center of gravity from rising as much when the body passes over the weight-bearing leg, keeping the center of gravity on a flatter path of action.
CG
Stride
Passing Position
Passing Position
Passing Position
Stride
CG
Walking is more efficient with pelvic list.
Path of Action ofCG without List
With Pelvic List
Walking Fo
rward
Knee Flexion of Weighted LegKnee flexes about 15 degrees immediately after heel strike and remains flexed until the center of gravity passes over the weight bearing leg.
Walking Fo
rward
Knee Flexion of Weighted Leg
Knee FlexionKnee flexion keeps the center of gravity from rising as much during the passing position.
Knee flexion also reduces the impact on the body at heel strike.
CG
Stride
Passing Position
Passing Position
Passing Position
Stride
CGPath of Action of CG without Flexion
With Flexion
Walking Fo
rward
Walking is more efficient with knee flexion.
Heel and ToeThe heel and toes of the foot combine with knee flexion to reduce the rising and falling of the center of gravity.
Heel increases effective length of the leg
Flexion reduces the leg length
Toes increase
leg length
Energy in Four-legged WalksHe
ight
x x x x x
Center of Gravity
Four-legged walking gait alternates passing position and stride between fore and hind legs to minimize energy required to lift the center of gravity.
The Journal of Experimental Biology 207, 3545-3558 (2004)
Next LectureLimbs and Joints
Homework 9 Stop Motion Animation #2
Due Thursday, November 10
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