CMT3331 New Media

AnimationPeter Passmore

Animation and computers

• Computers can be involved in many different stages of animation, generating frames, animating characters, compositing frames into sequences, in editing video and sound, distributing animations and much more

Contents

• In order to look at animation in a new media context we will– Define animation and how we perceive animations– Briefly consider the history of animation– Cover traditional animation techniques– Look at the principles of animation– Look at computer techniques for animation– 2D techniques– 3D techniques– Motion capture

What is animation - Wikipedia

• Animation is the rapid display of a sequence of images of 2-D or 3-D artwork or model positions in order to create an illusion of movement.

• The effect is an optical illusion of motion due to the phenomenon of persistence of vision, and can be created and demonstrated in several ways.

• The most common method of presenting animation is as a motion picture or video program, although there are other methods.

Persistence of vision and Phi

• Animation is possible because of the ways our brains work.

• It is intimately related to two psychological phenomena– Persistence of vision – and Phi

Persistence of vision

• If a series of images are shown quickly enough and they are coherent in that they relate to each other the user has the experience of smooth animation.

• At lower rates the images appear to flicker (< 15 frames per second)

Phi phenomena

• Wertheimer (1912) discovered that when two lights are switched off and on in sequence the light appears to move from one position to the other (the brain ascribes apparent movement when there isn’t any actually)

• Two illusions: A phantom dot appears to chase round a circle in an illusion where dots are successively switched on and off

Phi phenomena

• When previous sequence is slowed down the dots them selves appear to move.

• See the following for further discussion and examples of these illusions:

• http://www.aber.ac.uk/media/Modules/MC10220/visper08.html

History of animation

• There are many examples of attempts to capture motion pictorially over the ages from cave paintings through ancient Egypt etc. - usually depicted as sequences of images.

• A 5200 year old bowl from Persia (Iran) is possibly the oldest recorded animation (the bowl would have to be spun to see the animation). http://www.youtube.com/watch?v=gDqgrjG1Tv4

• Though there is some debate about when viewing systems were developed to view such sequences as animations the 19 century saw the development of a number of devices.

• See for more detail http://en.wikipedia.org/wiki/Animation

Phenakistoscope• The Phenakistoscope was one such device implemented by

Eadweard Muybridge (though invented earlier in the 19th centaury)

• A sequence of images with slits in between were printed on a circular disk. With the disk rotating around its centre when the images were viewed through the slits in a mirror an animation was seen.

• Muybridge was also known for his ground breaking photography which used multiple cameras to photograph sequences in real life, for example to show how a horses legs move while galloping.

• At the time many believed that the horse always had at least one foot on the ground (they don’t) . This was vital knowledge for future animators

History of animation- phenakistiscope

http://en.wikipedia.org/wiki/Phenakistoscope

Eadweard Muybridge’s capture of horse locomotion

• http://en.wikipedia.org/wiki/Eadweard_Muybridge

The flip book

• The flip book is probably an animation device that you are more familiar with, which was developed around about the same time.

• The first flip book was patented in 1868 by John Barnes Linnet.

• Its still a great way to try out quick ideas.• http://www.howcast.com/videos/1085-How-T

o-Create-a-Flip-Book

Traditional animation.

• Traditional animation involves producing frames of animation using film.

• Typically one drawing is produced for each frame of animation.

• Various different techniques could be used.

The first cartoon.

• First generally accepted cartoon Humorous Phases of Funny Faces is a silent cartoon by J. Stuart Blackton released in 1906. Shows animation by drawing, also (clown with dog) of cutout (simple puppet) animation.

• http://www.youtube.com/watch?v=8dRe85cNXwg

Cartoon evolution

• Cartoons evolved slowly to use sound and even into feature length cartoons.

• Walt Disney's Snow White and the Seven Dwarfs released 1937 was the first to become really successful and well-known.

• It was also the first cartoon top use cell animation.

Cel animation

• Cel animations is called so be cause sheets of transparent celluloid (cels) were used to create images.

• This meant that a background could be painted once and then a series of cels could be used to show successive animation of a character over the same background.

• Many cels could be used to make more complex scenes, to characters and a background are shown overleaf.

• http://en.wikipedia.org/wiki/Traditional_animation

Cel animation.

• In traditional animation pencil tests are produced first – pencil drawing of key frames that show the essential animation produced quickly to fit a sound track roughly

• Then the line drawings of key frames and inbetween frames are produced.

• These were then inked in by hand.• Master animators would produce the key frames,

more junior animator the key frames, and the inking was often outsourced

Stop motion animation

• In this case a physical model, usually 3D (but could be 2D) is moved little bit for each frame, then the camera takes a frame, it is moved a little more, another frame is taken etc

• This sequence is from the Seventh voyage of Sinbad

• http://www.youtube.com/watch?v=a77pycC78Q0

• Whats the problem with this?

Principles of animation

• Disney animators Ollie Johnston and Frank Thomas in their 1981 book The Illusion of Life: Disney Animation introduced the 12 principles of animation.

• Although applied to hand drawn animation they are just as relevant to computer animation.

Principles: 1 Squash and stretch

• Gives sense of weight and volume and flexibility.

• Object should deform as they move e.g. bouncing ball squashes as it hit the floor and stretches as it moves up etc.

• The objects volume is usually conserved.

• http://en.wikipedia.org/wiki/12_basic_principles_of_animation

Principles: 2 Anticipation

• Is movement that precedes and action and prepares the audience for it.

• It is often necessary in real life anyway e.g. crouching before jumping, a golfers backswing etc

Principles: 3 Staging

• This is the same as in real acting. A pose or action should clearly communicate the emotion, thought, action or idea of the character/s.

• This underlies clearly telling a story, sop for example theres should not be too many things happening at one time, and the importance action should always be in focus.

Principles: 4 Straight Ahead and Pose to pose animation

• Straight ahead is where animation starts fro first drawing and justs goes on and on from there. This is more spontaneous.

• Pose to pose involves defining keyframe poses and then defining the inbetween frames to connect them. This is more controlled, and most used

Principles: 5 Follow through and overlapping action.

• Follow through is like the reverse of anticipation – when the actor stops moving various parts may follow through the action such as the arms and legs and hair continuing to move

• Overlapping action is related to the start of an action, when the character starts to move various parts may experience drag, and only start to move some time later e.g. a dress may only start to move after a character starts to dance.

Principles: 6 Slow in and slow out

• This relates to movements in the real world, there is an acceleration stage when the movement starts and a deceleration phase when it finishes.

• This means from one pose to another there are more frames and the beginning and end

Principles: 7 Arcs

• Most actions by living objects follow arcs not straight lines e.g. your foot moves in an arc because of rotation on the knee, you jump in an arc because of gravity etc

Principles: 8 Secondary action

• Is an action that may supplement the main action e.g. an angry person shouting waving their arms to emphasise their anger.

Principles: 9 Timing

• Good timing comes with experience and practice.

• It can indicate for example the weight of an object (a heavy object moves slower etc) or its size (bigger object moves slower), or an emotion (a sad character may walk slower etc).

Principles: 10 Exaggeration.

• Exaggeration can help to tell at story and give more appeal, it is usually achieved by exaggerating the emotions of characters through changes in facial features and movements

Principles: 11 Solid drawing

• Even if drawing in 2D the drawing should be on solid 3 dimensional objects that generally conserve form, weight and volume.

Principles: 12 Appeal

• Characters have to appeal to you however they are e.g. evil, heroic, tragic, or cute

• This may be done in the way the look move and act, but also in how their personalities are revealed and how they develop over time.

Principles: Other things

• There are other principles that may be applied like – alternative physics (e.g. You can only fall if you

realise you are in the air)– The use of streak lines to indicate motion blur

Computer animation

• Computer animation is largely the digital version of frame by frame animation used in 2D animation, and stop motion animation of 3D models used in traditional animation.

• It is more controllable than physical processes using models and actors

• Many possibilities for automating various processes exist

• There still needs to be creative input

Types of Animation

• 2D space, very simple – e.g. transitioning between screens. A more complex example is 2D morphing (see later) + many simple animation effects in web pages

• 2½D illusion of depth is created in 2D – e.g. a drawing of something three dimensional, like cartoons

• 3D complex and realistic – e.g. an image of an object that has actually been modelled in 3D

2D transformations

• At its simplest computer animation automates translation, scaling and rotation of images

• Variations on these effects produce can transitions between screens in presentations like powerpoint or in scenes in videos

• In two games much of the animation behaviour can be programmed using images of various poses and transformations

Transitions

• A transition is a very simple animation that involves a simple transition between screens, e.g. wipes and dissolves etc

• You can see these transitions in powerpoint by clicking on transitions, and the choosing a transition which will preview immediately

• E.g. see http://www.youtube.com/watch?v=cAd_nWe5Bz8

• Examples trasnition using Adobe Aftereffects• http://www.youtube.com/watch?v=6OLhijw90gY&f

eature=related

Image morphing

• . . . Is a 2D transition where two sets of corresponding points are defined in two images

• Points in the one image are successively moved towards the points in the second image while the colours of individual pixels transition from the start colour to the end colour

• E.g. Brangelina (Angelina Jolie morphs to Brad Pitt)

• http://www.youtube.com/watch?v=Vni4zR52bSk&feature=related

http://www.shortcourses.com/display/display3-6.html

More complex 2D and 3D animations

• More complex animations • Usually a tell a story• Usually involve character animation• Engage the user emotionally in some way• E.g. adverts, cartoons, films, game sequences

Animation in 2D games

• A sprite in a 2d game is an image that you can transform in various ways such as translation (moving), scaling and rotation.

• In order to make a character do some thing more complicated animation is achieved by showing the character in different poses

• E.g. showing sprite with left leg forward then right leg forward with translation gives the impression of walking

• Overleaf is a sprite sheet for a fighting ninja

• http://www.36peas.com/blog/2010/9/13/free-japanese-ninja-shinobi-sprite-sheet.html

2D animation

• In modern cell animations can involve computers and software in all stages of the process from drawing and inking, tweening (generating in between frames between keyframes) to compositing images and sequences into animations and syncing with sound.

• It is now unusual to see a commercial animation that has not been made digitally – which greatly speed up production in various ways depending on the specific techniques used.

Modern cartoon software

• Some systems, such as those used by Pixar are proprietary

• Others professional systems include ToonBoom Digital pro/Harmony, Toonz,

• For beginners there is a cut down version of Toon boom, Claymation Studio, Animate Pro, Anima Studio Debut, also Adobe Flash, Aftereffects, and other tools including composition software

Modern cartoon software

• Some systems, such as those used by Pixar are proprietary

• Others professional systems include ToonBoom Digital pro/Harmony, Toonz,

• For beginners there is a cut down version of Toon boom, Claymation Studio, Animate Pro, Anima Studio Debut, also Adobe Flash, Aftereffects, and other tools including composition software

Stop motion revisited - Motion blur

• In real life when objects move fast they appear blurred in the direction of movement

• Unfortunately stop motion films cant do this and this always make them seem jerky and unrealistic

• It can be achieved by computer animation though• Overleaf look how blurred thr bus appears as it

passes a telephone box.• In the dog image note how you can tell which bits

are moving fastest by the amount of blur.

• http://en.wikipedia.org/wiki/Motion_blur

Stop motion revisited -Lego animations

• “Brick Flicks” have become a recent phenomenon – making stop motion films out of Lego and other bricks

• Anybody can now make a stop animation with a digital camera, some compositing software, Lego, and a little imagination

• E.g. http://www.archive.org/details/gta_lego_city• Or look for the “circle circle dot dot” viral video

but prepare to be offended

Stop motion revisited - Machinima

• This term comes from machine cinema. It involves animation projects that record the action in real-time interactive 3D environments, such as single-player video games or Second Life.

• http://secondlife.com/landing/maymachinima• http://www.youtube.com/watch?v=rGJXPDAZ

W20&list=PL5BB2B9C9FFE8EBC2&context=C307f5dbADOEgsToPDskJtn_o-rmi949nJX7sDz4-C

Computer animation techniques

• Other techniques we will consider are– Animation of articulated objects– Soft object animation– Animation of fuzzy objects and flocking– Motion capture

Articulated objects

• an articulated figure is made of series of rigid links connected at joints (i.e. humans, animals, insects, robots)

• from robotics the free end of a chain is known as the end effector

• Are popular because of the desire to model human beings

• Most 3d modelling packages allow the user to create some kind of bone system that can be attached to a 3d mesh to create a skinned mesh.

Skinned Mesh

• A skinned mesh is a mesh which has been animated with a bone system

• A bone system is an articulated hierarchy (as described earlier)

• However the bones are not rendered, the mesh is linked to the bone system

• Allows the mesh to be stretched and deformed naturally during animation, just as your skin does around your knees and elbows

Bones, bones and mesh, skinned mesh

The solid yellow bones top left are used with forward kinematics, the leg bones are used with inverse kinematics (example from

3D studio MAX)

Forward kinematics

• animation of articulated structures usually done by forward or inverse kinematics

• forward kinematics - motion of all joints explicitly specified by animator

• motion of an end effector (e.g. hand) is determined indirectly as the tree of the structure is descended e.g.: motion of a foot produced by the combined effect of transformations at the hip, knee, and ankle

Inverse kinematics• inverse kinematics - (goal directed motion) animator specifies the position

of the end effector and inverse kinematics solves the movements necessary at other links

• inverse kinematics will consider physical constraints as well as performance constraints - user may specify constraints such as energy minimisation, momentum conservation etc.

• inverse kinematics has to address the problems of: is there a solution, which is the best solution from possibly many solutions, and what method of determining a solution is to be used

• for both methods become increasingly difficult as the complexity of the articulated structure increases

• inverse kinematics seems an attractive high level way to specify motion but it is computationally expensive and constraints may be unnatural

• forward kinematics is more flexible and more widely used at present

Animating soft objects

• One way of modelling a soft object is to deform the space that it is in using Free Form Deformation (FFD)

• like putting soft objects in a flexible transparent block of Perspex which you can squash and stretch

• when you deform the block the objects inside are deformed in a corresponding natural way

• In a modelling package a volume of control points are defined that the user can drag to deform and objects. See for example:

• http://www.youtube.com/watch?v=seM2ZulCuhM• . . . Or the sad bag of flour:• http://www.youtube.com/watch?v=ecUDOL_nhqE

Procedural animation

• Sometimes in animation it is easier to write programs that can build and animate objects

• E.g. generating leaves or blades of grass• Generating smoke, fire, water

Particle systems

• Particle systems are used to model diffuse or fuzzy objects like fire, smoke, water and clouds

• A particle system is made of a set of particles whose behaviour and appearance over time is controlled by a set of rules.

• For example to model fire particles can be generated at some place in space (an emitter) and made to move up over time semi-randomly and change colour from bright yellow to dark red, and then die.

• By changing the rules and how particles are render you can model different phenomena

• http://www.youtube.com/watch?v=7wWsYTYGX78

Flocking

• Giving particles more complex rendering and different rules can produce flocking or schooling behaviour.

• Who is the leader in a flock, and how do they decide to go where?

Flocking

• No one is the leader the flocking emerges from individual birds implements the same set of rules– They want to be near the centre of the flock– They want to fly at about the same speed and direction as

their neighbours– They want to avoid collisions

• Boids in this example an extra rule to follow the ball is given: http://www.youtube.com/watch?v=GUkjC-69vaw

• Techniques widely adapted to use in games and films, e.g. the lion king

• http://www.youtube.com/watch?v=2m-42ek85G4

3D tools for animation

• There are many tools for doing 3D animation which incorporate many of the techniques discussed. The main ones include

• Maya – you can get a free student version• 3D Studio - you can get a free student version• Lightwave • Blender - free

Motion Capture

• The motions of an actor are tracked using various kinds of sensors and technology e.g. using multiple cameras to track markers attached to the body

Motion Capture

• http://en.wikipedia.org/wiki/Motion_capture

Performance capture

When motion capture is particularly detailed (e.g. facial animation) it is often referred to as performance captureAvatar used extensive performance capture.• http://www.youtube.com/watch?v=AN4ODuz4z

5U&feature=related• More detail:

http://www.youtube.com/watch?v=1wK1Ixr-UmM&feature=related

• Real time facial performance capture• http://www.youtube.com/watch?v=8kbPhG3y8

ts

Distribution of animation

• You tube• Vimeo etc