cnm 190 advanced digital animation lec 12 : walk cycles & autonomous motion

CNM 190CNM 190Advanced Digital AnimationAdvanced Digital Animation

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

Greg Niemeyer, Art (co-instructor)Greg Niemeyer, Art (co-instructor)

Jeremy Huddleston, EECS (TA)Jeremy Huddleston, EECS (TA)

John Cleese “Silly Walk” animated using SPAM softwareJohn Cleese “Silly Walk” animated using SPAM software

2/24Walk Cycles & Autonomous Motionhttp://inst.eecs.berkeley.edu/~selfpace/CNM190

OverviewOverview

Walk CyclesWalk Cycles Definition, Definition,

HistoryHistory ReferencesReferences What makes a What makes a

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

Autonomous MotionAutonomous Motion DefinitionDefinition Flow ChartFlow Chart Finite State Finite State

MachinesMachines Brian Mirtich DemoBrian Mirtich Demo


Walk Cycles : Definition & Walk Cycles : Definition & HistoryHistory

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 B these have been used to get characters from A to B and, most importantly, to and, most importantly, to capture & convey capture & convey emotionemotion

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

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.


References (1)References (1) The Illusion of LifeThe Illusion of Life : :

Disney AnimationDisney Animation by Frank Thomas & Ollie by Frank Thomas & Ollie

JohnstonJohnston Two of Disney’s Two of Disney’s

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

into the workings of the into the workings of the animation masters at animation masters at Disney's during the Disney's during the Golden Age of Golden Age of animation”animation”

On every professional On every professional animator’s bookshelfanimator’s bookshelf

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

en.wikipedia.org/wiki/The_Illusion_Of_Life




References (2)References (2) The Animator’s Survival The Animator’s Survival

KitKit 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






References (3)References (3)

Principles of Principles of Traditional Animation Traditional Animation Applied to 3D Applied to 3D Computer AnimationComputer Animation, , Computer Graphics, Computer Graphics, pp. 35-44, 21:4, July pp. 35-44, 21:4, July 1987 (SIGGRAPH 87).1987 (SIGGRAPH 87). by John Lasseterby John Lasseter He shared the secrets of He shared the secrets of

the kingdom with 3D the kingdom with 3D animatorsanimators

There’s an abridged There’s an abridged version online (URL above)version online (URL above)

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


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

Four distinct posesFour distinct poses Contact – feet at furthest extension of walk (start Contact – feet at furthest extension of walk (start

here)here) Recoil – where the character impacts the groundRecoil – where the character impacts the ground Passing – an ‘in-between’ of Recoil and High PointPassing – an ‘in-between’ of Recoil and High Point High Point – character’s body stretched to maxHigh Point – character’s body stretched to max

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





Depending on the Depending on the emotion to convey, emotion to convey, these four basic these four basic poses may changeposes may change No 2-pt contact pose No 2-pt contact pose

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

requires more than 4 requires more than 4 posesposes

Note several thingsNote several things Path of headPath of head Lean of body, headLean of body, head Arms & hands Arms & hands

matter!matter!

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



Preston Blair’s Walk Cycles



Four-legged figures Four-legged figures are similar, but are similar, but more complicatedmore complicated Are legs in phase?Are legs in phase? Horses have vastly Horses have vastly

different cycles different cycles depending on depending on speedspeed

This is relevant for This is relevant for both teamsboth teams Elephants, GiraffesElephants, Giraffes Robot DogRobot Dog

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



Preston Blair’s Walk Cycles



Red line shows off-Red line shows off-balance lean for a balance lean for a typical walk cycletypical walk cycle

Happy charactersHappy characters Bouncy, more time Bouncy, more time

up in the air than up in the air than downdown

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

Step distance also Step distance also signals emotion, signals emotion, ageage Older, shy Older, shy shuffle shuffle

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





The walk cycle The walk cycle should have good, should have good, consistent consistent transverse transverse motions (L-R)motions (L-R) E.g., Note arms; E.g., Note arms;

they don’t just they don’t just rotate in direction rotate in direction of walkof walk

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


Examples of WalksExamples of Walks

Fortunately, it’s easy Fortunately, it’s easy to act out a walk & to act out a walk & film it for analysisfilm it for analysis

Humans good atHumans good at reading impossible reading impossible

and bad walksand bad walks reading emotion from reading emotion from

walkswalks Make sure to convey Make sure to convey

weight, balanceweight, balance Practice, practicePractice, practice Let’s see some Let’s see some

examplesexamples

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

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

Monty Python’s Ministry of Silly Walks




SPAM – FK Walk EditorSPAM – FK Walk Editor I wrote a forward-I wrote a forward-

kinematic walk editor back kinematic walk editor back in 1994in 1994

It uses a cubic BIt uses a cubic Bézier ézier spline to interpolate:spline 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 foot as I start at forward foot as root and work up & downroot and work up & down

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


Walk Generation –Walk Generation – Use Use MoCap!MoCap!

We saw a MoCap We saw a MoCap demo last week demo last week

With a talented With a talented actor, you can actor, you can create any human create any human motionmotion E.g., LoTR “Gollum”E.g., LoTR “Gollum” You can also use the You can also use the

data as a starting data as a starting point for editingpoint for editing

Might be lots of raw Might be lots of raw data cleaning updata cleaning up

Purists don’t use itPurists don’t use it

en.wikipedia.org/wiki/Motion_capture




Walk Cycle Summary…Walk Cycle Summary…PersonalityPersonality

““The objective of the The objective of the [Animation] principles [Animation] principles previously discussed [in his previously discussed [in his SIGGRAPH paper] are to give SIGGRAPH paper] are to give the characters in an animation the characters in an animation a personality that appeals to a personality that appeals to the viewersthe viewers.”.”

““The different principles The different principles should be applied in a fashion should be applied in a fashion to produce a consistent to produce a consistent personality.” personality.”

““This means that This means that the animator the animator must have a good idea of the must have a good idea of the desired personality desired personality beforebefore beginning the animationbeginning the animation.”.”



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


UCB Walk-Related ResearchUCB Walk-Related Research

There has been a lot of There has been a lot of research done here research done here relating to walk cycles relating to walk cycles & MoCap databases& MoCap databases Electronic Arts gave us Electronic Arts gave us

some of their MoCap some of their MoCap datadata

Okan Arikan (now a Prof Okan Arikan (now a Prof at U Texas) led charge, at U Texas) led charge, with Profs O’Brien, with Profs O’Brien, ForsythForsyth

Knowing When to Put Knowing When to Put Your Food DownYour Food Down

Pushing people aroundPushing people around Motion Synthesis from Motion Synthesis from

AnnotationsAnnotations Motion Synthesis & Motion Synthesis &

RetargetingRetargeting










3 UCB MooVs

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


Autonomous MotionAutonomous Motion More than simply More than simply

spacetime spacetime constraintsconstraints

This field is VAST, for This field is VAST, for some the Holy Grail!some the Holy Grail! Artificial intelligenceArtificial intelligence Artificial lifeArtificial life RoboticsRobotics Video gamesVideo games Crowd, herd & Crowd, herd &

flocking simulationsflocking simulations Real-time >> BatchReal-time >> Batch

In terms of $, interestIn terms of $, interest








Autonomous Animated Autonomous Animated CharactersCharacters

Here’s a general framework…Here’s a general framework…



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

WhyWhyWhere Where

HowHow


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

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

generated / issued?generated / issued? Where do we go?Where do we go? What is the emotion?What is the emotion? What’s our What’s our

motivation?motivation? What is our mood as What is our mood as

the result of the new the result of the new motion / location?motion / location?

When do we have When do we have births / deaths?births / deaths?

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

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

animation?animation? blend the animations blend the animations

we have with what is we have with what is requested?requested?

retarget animations retarget animations to capture request?to capture request?

scale pre-set motions scale pre-set motions for new characters?for new characters?


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

VERY powerful ideaVERY powerful idea Model of behavior Model of behavior

composed of composed of statesstates, , transitionstransitions & & actionsactions

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

TransitionTransition Condition that triggers Condition that triggers

state changestate change ActionAction

Activity performed at Activity performed at a given momenta given moment

en.wikipedia.org/wiki/Finite_state_machine

FSM for gum machine




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

4 Kinds of Actions. For 4 Kinds of Actions. For each, “Execute action each, “Execute action _”_” EntryEntry : …when : …when

ENTERING stateENTERING state ExitExit : …when EXITING : …when EXITING

statestate InputInput : …dependent on : …dependent on

present state and input present state and input conditionsconditions

TransitionTransition :…when :…when performing a transitionperforming a transition

en.wikipedia.org/wiki/Finite_state_machine




Brian Mirtich, 1996 UCB Brian Mirtich, 1996 UCB Ph.D.Ph.D.

Thesis: “Thesis: “ImpulseImpulse - -based Dynamic based Dynamic Simulation of Rigid Simulation of Rigid Body Systems”Body Systems” He focused on He focused on

dynamic constraintsdynamic constraints Very cool work!Very cool work!

““Creature War” Creature War” demodemo His purpose: show His purpose: show

off his simulatoroff his simulator Great example of Great example of

FSM-based AI!FSM-based AI!


Mirtich’s Creature War

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


Boids – Distributed Boids – Distributed Behavior Behavior

Big idea : Give many Big idea : Give many characters their own FSMcharacters their own FSM

Craig Reynolds Craig Reynolds “founded” first Boids in “founded” first Boids in 1986; A-Life1986; A-Life SeparationSeparation – steer to avoid – steer to avoid

crowding local flockmatescrowding local flockmates AlignmentAlignment – steer towards – steer towards

the average heading of the average heading of local flockmateslocal flockmates

CohesionCohesion – steer to move – steer to move toward the average toward the average position of local flockmates position of local flockmates

Emergent behavoir!Emergent behavoir! CrowdsCrowds just another just another

example of same idea…example of same idea…

www.red3d.com/cwr/boids


Boids Applet, Movie, It’s a Big Ad


ConclusionConclusion Autonomous Motion Autonomous Motion

(incl Walking) is the (incl Walking) is the goal of many (esp goal of many (esp games!!)games!!)

Imagine virtual actors Imagine virtual actors interacting in real timeinteracting in real time What do they want to do What do they want to do

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

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

born?born? FSM key to it all!FSM key to it all! Strong vs Weak AIStrong vs Weak AI

Strong: An amazing FSM Strong: An amazing FSM can have “sentience”!can have “sentience”!

Commander Data from Star Trek

en.wikipedia.org/wiki/Strong_AI

cnm 190 advanced digital animation lec 12 : walk cycles & autonomous motion

Documents

great walk cycle

selfpacecnm190walk cycles

different cycles

walk movementhistorysince

furthest extension of

typical walk cyclehappy

eecs tajohn cleese silly

d computer animation