Upcoming Deadlines Homework #8 - Reverse Video Reference of Walking Due Wednesday, October 27 th...
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Upcoming DeadlinesHomework #8 - Reverse Video Reference of WalkingDue Wednesday, October 27th (This Wednesday)20 points (10 points if late); 20 point bonus to best for each clip
Homework #9 Stop-motion character AnimationDue Wednesday, November 3rdth (Next week)20 points (10 points if late); 20 point bonus to top 3
For full schedule, visit course website:ArtPhysics123.pbworks.comPick up a clicker, find the right channel, and enter Student ID
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 #9http://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.Inhomework assignment #6you 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 Wed., November 3rd
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.
Extra Credit OpportunityNovember 1114, 2010 Landmark's Embarcadero Center Cinemahttp://www.sffs.org/Screenings-and-Events/Fall-Season.aspxPresent proof of your attendance (receipt, photos, etc.) to any festival event or screening for 10 points of extra credit.
Special Campus EventRon DiamondsAnimation Show of Shows Friday October 29 7:30 PM Morris Dailey AuditoriumFree Admission
Activating your Clicker* Turn on your clicker.* Enter the channel number or letter for joining this class. Hit Enter/Send key.* Clicker should read AP123GF10* 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.
Survey QuestionMany videos are shown in this class; would you say that the number of videos is:Too many. Use the class time for other stuff.About the right balance.Not enough. Add more and leave out other stuff.
Review QuestionIn the passing position the pelvis drops slightly on the non-weight bearing side. This motion is called:Pelvic rotationPelvic listKnee flexionHip hula-hulaThe Twist
Pelvic ListPelvic 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. CGStridePassing PositionPassing PositionPassing PositionStrideCGWalking is more efficient with pelvic list.Path of Action of CG without ListWith Pelvic ListB) Pelvic list
Review QuestionIn normal walking, the side-to-side and up-down motion shown here is for the:
LegArmCenter of gravityHeel of the footHandSlowFastSide-to-SideUp & DownWalking ForwardFigure 8 Loop
8-Loop & U-LoopC) Center of Gravity
The center of gravity shifts up & down and also side-to-side. CG makes a Figure-8 loop when walking slow Makes a U-shape loop when walking fast.SlowFastSide-to-SideUp & DownWalking ForwardFigure 8 Loop
Joints & Levers
Toy Story (1995)Pixars Toy Story, directed by John Lasseter, was the first full-length feature film using computer animation.Tin Toy (1988, Pixar), also directed by Lasseter, won an Oscar in 1988 for Animated Short Film.
Tin Toy (1988)http://www.youtube.com/watch?v=vNZtl5SZvbM
The Polar Express (2004)The Polar Express was first full-length feature film made entirely with motion-capture animation.http://www.youtube.com/watch?v=2g-FRSq7x_o
Uncanny ValleyParadoxically, as computer generated characters get more realistic they start to be creepy.Realism Appeal Emily ProjectPolarExpressShrek 1BeowulfToy StoryTin Toyhttp://www.youtube.com/ watch?v=GBgURIUQ700
Realism TightropeThe uncanny valley occurs when some elements are more realistic than others.
Our human instincts warn us something is wrong.Realistic Image Appeal Realistic MotionCompletely NaturalTolerableRepulsiveRepulsiveRobotZombieTolerable
Articulated FiguresIn computer animation characters are articulated figures, like marionette puppets.The challenge for animators is to move all the elements (arms, legs, hands, etc.) believably from frame to frame.
JointsRevolute JointPrismatic Joint (Slider)Two kinds of joints: Revolute (rotation) and Prismatic (extension/contraction).Nearly all joints in animals are revolute joints
Axis of RotationRotation occurs around a line called the axis of rotation.The axel is the axis of rotation for a set of wheels.
Revolute JointsRevolute joints may have a single axis of rotation, like hinge joints and pivot joints, or a variable axis, such as the ball and socket joint.ElbowShoulderForearm
Forward KineticsWith forward kinetics (FK) the animator has to specify the axis of rotation and the angle of rotation for each joint on a moving limb.Lift the arm by a shoulder rotationMove forearm by an elbow rotation
Forward KineticsForward kinetics (FK) is a tedious process for the animator and it is difficult to maintain certain constraints, such as the planted foot in a walk.
Inverse KineticsWith inverse kinetics (IK) the animator positions the end effector, such as the hand, and the computer calculates the required joint rotations.
Inverse KineticsRotations calculated by the computer using IK are not always natural poses performed by a person. Furthermore, the timing may not be correct.Ball & SocketBall & SocketHingexxRaising hand into High Five poseAwkwardIK PoseElbowWristShoulder
Understanding RotationJust like any other type of motion, rotation is governed by Newtons laws:
Law of Inertia Law of Acceleration Action-Reaction Principle
Lets see how inertia, force, reaction, etc. appear in the context of rotational motion.Sir Isaac Newton
Mass is a measure of inertia for linear motion.
Rotational inertia is similar concept for rotation.
InertiaMmGold brickNormal brickDifficult to moveEasy to movexxWood BatPlastic Pee-wee BatDifficult to RotateEasy to Rotate
Rotational InertiaRotational inertia depends on: Total mass of the objectHow the mass is distributed
The farther the objects mass is from the axis of rotation, the larger the rotational inertia.
Demo: Inertia SticksTwo metal pipes of the same massRotateAxis ofRotation
Human Rotational InertiaIn which pose does the dancer have a larger rotational inertia?
Axis of RotationABPose APose BSame for A & B since mass is unchanged.
Human Rotational InertiaAxis of RotationABB) Pose B
Pose B has larger rotational inertia since the leg is extended, putting mass further from the axis of rotation.
Demo: Long LegsLong legs have greater rotational inertia than short legs so long legged animals have a slow walking stride.
Drag of Articulated LimbsFast SwingSlow SwingSlowFastThe greater rotational inertia of longer limbs results in drag, just like with hair and fabrics.
Demo: Drop the StickTwo meter sticks stand upright against a wall; one has a hunk of clay on the end. Which stick will swing down and hit the floor first?The one without the hunk of clay.Why?Clay increases rotational inertia, which slows the rotation.Axis of Rotation
Demo: Drop the StickAxis of RotationX CGX CGAnother way to understand why the weighted stick takes longer to fall is that its center of gravity is higher.
The higher it is, the longer it takes for an object to fall to the ground.Longer stick tips over more slowly
Tripping and FallingAxis of RotationX CGX CGIf small child trips, he hits the ground more quickly than an adult.Can view this two ways:*Child has small rotational inertia.*Childs center of gravity is initially closer to the ground.
Demo: Hammer BalanceAxis of RotationIn which case is the hammer easier to balance on your finger?
Case ACase BThe same for A & B
Demo: Hammer BalanceB) Case BIn Case B the rotation is slower and thus easier to balance.In case B the rotational inertia is greater because most of the mass is far from the axis of rotation (at your fingertip). X CGX CG
Tightrope WalkersThe Great Blondin Is First to Walk Across Niagara Falls (June 30, 1859)Tightrope walkers carry a long pole to increase their rotational inertia, which slows their rotation when theyre off balance.
When a force causes a rotation, we identify this as a torque.
Torque depends onMagnitude of ForceLever Arm
(Torque) = (Force) x (Lever Arm)Torque
Lever ArmLever arm is the perpendicular distance