walk cycles : definition & history references (1)cs194-8/fa06sp07/... · 2006-11-13 · the...

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CNM 190CNM 190Advanced Digital AnimationAdvanced Digital Animation

Lec Lec 12 : Walk Cycles & Autonomous Motion12 : Walk Cycles & Autonomous MotionDan GarciaDan Garcia, EECS (co-instructor), EECS (co-instructor)

Greg Niemeyer, Art (co-instructor)Greg Niemeyer, Art (co-instructor)Jeremy HuddlestonJeremy Huddleston,, EECS (TA) EECS (TA)

John John Cleese Cleese ““Silly WalkSilly Walk”” animated using SPAM softwareanimated using SPAM software

2/24Walk Cycles & Autonomous Motionhttp://inst.eecs.berkeley.edu/~selfpace/

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OverviewOverview

Walk CyclesWalk Cycles Definition, HistoryDefinition, History ReferencesReferences What makes aWhat makes a

great walk cycle?great walk cycle? ExamplesExamples SPAM demoSPAM demo UCB ResearchUCB Research

Autonomous MotionAutonomous Motion DefinitionDefinition Flow ChartFlow Chart Finite State MachinesFinite State Machines Brian Brian Mirtich Mirtich DemoDemo


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Walk Cycles : Definition & HistoryWalk Cycles : Definition & History

DefinitionDefinition A sequence of frames capturing a walk movementA sequence of frames capturing a walk movement

HistoryHistory Since the early days of hand-drawn animation,Since the early days of hand-drawn animation,

these have been used to get characters from A to Bthese have been used to get characters from A to Band, most importantly, to and, most importantly, to capture & convey emotioncapture & convey emotion

www.idleworm.com/how/anm/02w/walk1.shtml


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References (1)References (1)

The Illusion of LifeThe Illusion of Life : :Disney AnimationDisney Animation by Frankby Frank Thomas & OllieThomas & Ollie

JohnstonJohnston Two of DisneyTwo of Disney’’ss

““Nine Old MenNine Old Men”” “…“… gives many glimpses gives many glimpses

into the workings of theinto the workings of theanimation masters atanimation masters atDisney's during theDisney's during theGolden Age of animationGolden Age of animation””

On every professionalOn every professionalanimatoranimator’’s bookshelfs bookshelf

576 Pages576 Pages Disney Editions, 1995Disney Editions, 1995 Out-of-print! ~$40Out-of-print! ~$40

en.wikipedia.org/wiki/The_Illusion_Of_Life


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References (2)References (2) The AnimatorThe Animator’’s Survival Kits Survival Kit

by Richard Williamsby Richard Williams 352 pages352 pages Faber & Faber, 2002Faber & Faber, 2002 ~$20 new, ~$15 used~$20 new, ~$15 used

Cartoon AnimationCartoon Animation by Preston Blairby Preston Blair 144 pages144 pages Walter Foster, 1994Walter Foster, 1994 ~$15 new, ~$10 used~$15 new, ~$10 used

www.amazon.com


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References (3)References (3)

Principles of TraditionalPrinciples of TraditionalAnimation Applied toAnimation Applied to3D Computer3D ComputerAnimationAnimation, Computer, ComputerGraphics, pp. 35-44,Graphics, pp. 35-44,21:4, July 198721:4, July 1987(SIGGRAPH 87).(SIGGRAPH 87). by John by John LasseterLasseter He shared the secrets of theHe shared the secrets of the

kingdom with 3D animatorskingdom with 3D animators ThereThere’’s an abridged versions an abridged version

online (URL above)online (URL above)

www.siggraph.org/education/materials/HyperGraph/animation/character_animation/principles/prin_trad_anim.htm

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What makes a great walk cycle? (1)What makes a great walk cycle? (1)

Four distinct posesFour distinct poses Contact Contact –– feet at furthest extension of walk (start here) feet at furthest extension of walk (start here) Recoil Recoil –– where the character impacts the ground where the character impacts the ground Passing Passing –– an an ‘‘in-betweenin-between’’ of of Recoil and High PointRecoil and High Point High PointHigh Point –– character character’’s body stretched to maxs body stretched to max

www.idleworm.com/how/anm/02w/walk1.shtml


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Depending on theDepending on theemotion to convey,emotion to convey,these four basicthese four basicposesposes may changemay change No 2-pt contact poseNo 2-pt contact pose

for run cyclesfor run cycles E.g., skipping requiresE.g., skipping requires

more thanmore than 4 poses4 poses

Note several thingsNote several things Path of headPath of head Lean ofLean of body, headbody, head ArmsArms & hands matter!& hands matter!

minyos.its.rmit.edu.au/~rpyjp/a_notes/walk_reference_01.html

Preston Blair’s Walk Cycles


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Four-legged figuresFour-legged figuresare similar, but moreare similar, but morecomplicatedcomplicated Are legs in phase?Are legs in phase? Horses have vastlyHorses have vastly

different cyclesdifferent cyclesdepending on speeddepending on speed

This is relevant forThis is relevant forboth teamsboth teams Elephants, GiraffesElephants, Giraffes Robot DogRobot Dog

minyos.its.rmit.edu.au/~rpyjp/a_notes/walk_reference_02.html

Preston Blair’s Walk Cycles10/24Walk Cycles & Autonomous Motion

http://inst.eecs.berkeley.edu/~selfpace/CNM190


Red line shows off-Red line shows off-balance leanbalance lean for afor atypical walk cycletypical walk cycle

Happy charactersHappy characters Bouncy, more time upBouncy, more time up

in the air than downin the air than down

Sad charactersSad characters Plod along, drag feetPlod along, drag feet

Step distance alsoStep distance alsosignals emotion, agesignals emotion, age Older, shy Older, shy shuffle shuffle

minyos.its.rmit.edu.au/~rpyjp/a_notes/04_walkcycle_project.html


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The walk cycleThe walk cycleshould have good,should have good,consistent transverseconsistent transversemotions (L-R)motions (L-R) E.g., Note arms; theyE.g., Note arms; they

dondon’’t just rotate int just rotate indirection of walkdirection of walk

minyos.its.rmit.edu.au/aim/a_notes/walk_reference_03.html


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Examples of WalksExamples of Walks

Fortunately, itFortunately, it’’s easy tos easy toact out a walk & film itact out a walk & film itfor analysisfor analysis

Humans good atHumans good at reading impossiblereading impossible andand

bad walksbad walks reading emotion fromreading emotion from

walkswalks

Make sure to conveyMake sure to conveyweight, balanceweight, balance

Practice, practicePractice, practice LetLet’’s see some exampless see some examples

minyos.its.rmit.edu.au/~rpyjp/a_notes/04_walkcycle_project.htmlwww.anticz.com/Walks.htm

Monty Python’s Ministry of Silly Walks

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SPAMSPAM –– FK Walk EditorFK Walk Editor

I wrote a I wrote a forward-kinematicforward-kinematicwalk editorwalk editor back in 1994back in 1994

It uses a cubic It uses a cubic BBézier splineézier splineto interpolate:to interpolate: Q(t) = Q(t) = VV00 (1-t) (1-t)33 + + VV11 3t (1-t)3t (1-t)22

+ + VV22 3t 3t22 (1-t) + (1-t) + VV33 t t33

I start at forward footI start at forward foot asasroot and work up & downroot and work up & down

digitalassets.lib.berkeley.edu/techreports/ucb/text/CSD-94-860.pdf


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Walk Generation Walk Generation –– Use Use MoCapMoCap!!

We sawWe saw a a MoCapMoCapdemo last weekdemo last week

With a talented actor,With a talented actor,you can create anyyou can create anyhuman motionhuman motion E.g., E.g., LoTR LoTR ““GollumGollum”” You can also use theYou can also use the

data as a startingdata as a startingpoint for editingpoint for editing

Might be lots of rawMight be lots of rawdata cleaning updata cleaning up

Purists donPurists don’’t use itt use it

en.wikipedia.org/wiki/Motion_capture


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Walk Cycle SummaryWalk Cycle Summary……PersonalityPersonality

““The objective of the [Animation]The objective of the [Animation]principles previously discussed [inprinciples previously discussed [inhis SIGGRAPH paper] are to givehis SIGGRAPH paper] are to givethe characters in an animation the characters in an animation aapersonality that appeals to thepersonality that appeals to theviewersviewers..””

““The different principles should beThe different principles should beapplied in a fashion to produce aapplied in a fashion to produce aconsistent personality.consistent personality.””

““This means that This means that the animatorthe animatormust have a good idea of themust have a good idea of thedesired personality desired personality beforebeforebeginning the animationbeginning the animation..””

www.siggraph.org/education/materials/HyperGraph/animation/character_animation/principles/personality.htm


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UCB Walk-Related ResearchUCB Walk-Related Research

There has been a lot ofThere has been a lot ofresearch done hereresearch done hererelating to walk cycles &relating to walk cycles &MoCap MoCap databasesdatabases Electronic Arts gave usElectronic Arts gave us

some of their some of their MoCap MoCap datadata Okan Arikan Okan Arikan (now a Prof(now a Prof

at U Texas) led charge,at U Texas) led charge,with Profs Owith Profs O’’Brien, ForsythBrien, Forsyth

Knowing When to PutKnowing When to PutYour Food DownYour Food Down

Pushing people aroundPushing people around Motion Synthesis fromMotion Synthesis from

AnnotationsAnnotations Motion Synthesis &Motion Synthesis &

RetargetingRetargeting3 UCB MooVs

www.cs.berkeley.edu/b-cam/www.cs.utexas.edu/~okan/


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Autonomous MotionAutonomous Motion

More than simplyMore than simplyspacetime spacetime constraintsconstraints

This fieldThis field is VAST, foris VAST, forsome the Holy Grail!some the Holy Grail! Artificial intelligenceArtificial intelligence Artificial lifeArtificial life RoboticsRobotics Video gamesVideo games Crowd, herd & flockingCrowd, herd & flocking

simulationssimulations

Real-time >> BatchReal-time >> Batch In terms of $, interestIn terms of $, interest


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Autonomous Animated CharactersAutonomous Animated Characters

HereHere’’s a general frameworks a general framework……

www.kuffner.org/james/anim/framework.php

WhyWhyWhereWhere

HowHow

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Lots of questions ; this is hard!Lots of questions ; this is hard!

Why / Where,Why / Where,often in real timeoften in real time…… What behavior isWhat behavior is

generated /generated / issued?issued? Where do we go?Where do we go? What is the emotion?What is the emotion? WhatWhat’’s our motivation?s our motivation? What is our mood asWhat is our mood as

the result of the newthe result of the newmotion / location?motion / location?

When do we haveWhen do we havebirths / deaths?births / deaths?

How do we,How do we,often in real timeoften in real time…… select the animationsselect the animations

from DB? Orfrom DB? Or…… auto-generate theauto-generate the

animation?animation? blend the animationsblend the animations

we have with what iswe have with what isrequested?requested?

retarget animationsretarget animationsto capture request?to capture request?

scale pre-setscale pre-set motionsmotionsfor new characters?for new characters?


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Intelligence : Finite State Machines (1)Intelligence : Finite State Machines (1)

VERY powerful ideaVERY powerful idea Model of behaviorModel of behavior

composed of composed of statesstates,,transitionstransitions & & actionsactions

State (1 must be a start)State (1 must be a start) Past informationPast information

TransitionTransition Condition that triggersCondition that triggers

state changestate change

ActionAction Activity performed at aActivity performed at a

given momentgiven moment

en.wikipedia.org/wiki/Finite_state_machine

FSM for gum machine


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Intelligence : Finite State Machines (2)Intelligence : Finite State Machines (2)

4 Kinds of Actions. For4 Kinds of Actions. Foreach, each, ““Execute action _Execute action _”” EntryEntry : : ……when ENTERINGwhen ENTERING

statestate ExitExit : : ……when EXITINGwhen EXITING

statestate InputInput : : ……dependent ondependent on

present state and inputpresent state and inputconditionsconditions

TransitionTransition : :……whenwhenperforming a transitionperforming a transition

en.wikipedia.org/wiki/Finite_state_machine


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Brian Brian MirtichMirtich, 1996 UCB Ph.D., 1996 UCB Ph.D.

Thesis: Thesis: ““ImpulseImpulse - -based Dynamicbased DynamicSimulation of RigidSimulation of RigidBody SystemsBody Systems”” He focused onHe focused on

dynamic constraintsdynamic constraints Very cool work!Very cool work!

““Creature WarCreature War”” demo demo His purpose: show offHis purpose: show off

his simulatorhis simulator Great exampleGreat example ofof

FSM-based AI!FSM-based AI!Mirtich’s Creature War

www.kuffner.org/james/software/dynamics/mirtich/


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Boids Boids –– Distributed Behavior Distributed Behavior

Big idea : Give manyBig idea : Give manycharacters their own FSMcharacters their own FSM

Craig ReynoldsCraig Reynolds ““foundedfounded””first first Boids Boids in 1986; A-Lifein 1986; A-Life SeparationSeparation –– steer to avoid steer to avoid

crowding local crowding local flockmatesflockmates AlignmentAlignment –– steer towards steer towards

the average heading ofthe average heading oflocal local flockmatesflockmates

CohesionCohesion –– steer to move steer to movetoward the averagetoward the averageposition of local position of local flockmatesflockmates

Emergent Emergent behavoirbehavoir!! CrowdsCrowds just another just another

example of same ideaexample of same idea……

www.red3d.com/cwr/boids

Boids Applet, Movie, It’s a Big Ad


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ConclusionConclusion

Autonomous Motion (Autonomous Motion (inclinclWalking) is theWalking) is the goal ofgoal ofmany (many (esp esp games!!)games!!)

Imagine virtual actorsImagine virtual actorsinteracting in real timeinteracting in real time What do they want to doWhat do they want to do

and when?and when? How do they generateHow do they generate

smooth motion to do it?smooth motion to do it? Can actors die? Be born?Can actors die? Be born?

FSM key to it all!FSM key to it all! Strong Strong vs vs Weak AIWeak AI

Strong: An amazing FSMStrong: An amazing FSMcan have can have ““sentiencesentience””!! Commander Data from Star Trek

en.wikipedia.org/wiki/Strong_AI

walk cycles : definition & history references (1)cs194-8/fa06sp07/... · 2006-11-13 · the...

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