UNIT VI: Animation
Uses of animation
types of animation.
Principles of animation,
techniques of animation: Onion skinning, motion cycling, masking,
flip book animation, rotoscoping and blue screening, color cycling,
morphing,
animation on the web,
3D animation,
Creating animation.

Animation
Animate – to give life to
Rapid display of images in succession fools the eye into perceiving
continuous motion due to 'persistence of vision'
It deals with graphics drawn by individuals either by hand or by using
software.
It also involves a model which is changed by small amounts oat a time
and then repeatedly photographed – called stop motion animation.
Animation sequences are created by 2 types of artists :
1. lead artists / experts (who draw frames where major changes take
place in a sequence called KEY FRAMES)
2. Assistants draw a number of frames in between the key frames, a
process called TWEENING.

Key frames and tweening
Important / key frames are drawn by experts.
Intermediate frames are drawn by assistant
animators. This process is called tweening
(in between).
Animators find 18 increments of movement
projected at 24 frames / sec give a life like
result. Practically they draw nice motion
increments and then photograph each
frame twice.
Computers have made things easier.

Uses of animation
Entertainment Industry
Computer Games
Education
Industrial and Scientific
applications

Types of Animation
1. Cel Animation
Comes from Celluloid and refers to the transparent piece of
film that is used in hand drawn animation. Animation cels are
generally layered one on top of the other to produce
a single animation frame. Layering enables the
animator to isolate and redraw only the parts of
the image that change between successive frames.

Types of Animation
2. Path Animation (Sprite Animation)
Here animation does not exist as a collection of frames but rather as
mathematical entities called vectors stored by the animation program.
It involves an image or a collection of images together called a
sprite, that moves as an independent object like a flying bird, a
rotating planet etc. The sprite moves along a motion path typically
curved called splines.
The spline passes through a series of anchor points. Usually path
animation takes up less disk space compared to cel animation.

Types of Animation
3. 2D vs 3D animation
2D animation programs do not
consider depth of object and
depict them on flat (X-Y direction)
surfaces.
3D animation monitors objects by considering modeling,
rendering(process of generating an image from a model, by means of
computer programs) and adding surface properties, lighting and
camera motions.

Principles of animation
1. Squash and Stretch
Example : Bouncing ball. An object that changes the shape as it
strikes the ground and reverts back to the original shape as it
rebounds; gives a good effect.
2. Anticipation
“Prepare to act before we act” - animation should make this clear.
3. Staging
To arrange things in each frame so that the action is clear and
easy to see. Staging means to give emphasis to main
characters and to integrate them with the background.

Principles of animation
4. Follow-through and overlapping action
Follow through is the complement of anticipation. Eg – throwing a flying
disc action makes the arm move in a long continuous arc even after the
disc has been thrown. Anticipation and follow through combine in
overlapping action.
5. Slow in and slow out
A good effect of a bouncing ball would be to see it slow down when it is
rising and momentarily stop at the topmost point.
6. Arcs
The overall movement of characters in an animation should follow an arc
as well.
7. Secondary Action
Each part of a character might not move at the same rate.

Principles of animation
8. Timing
Speed of action is an important way to show a character's intent.
Rapid movement for emergencies and slow movement implies
deliberation. Timing also indicates weight.
9. Exaggeration
Exaggerating the important elements makes them stand out and
brings them closer to the viewer.
10. Appeal
Characters that are visually intriguing are more likely to hold an
audience's attention than characters whose appearance is
predictable or mundane.

techniques of animation
1. Onion Skinning
It is a drawing technique borrowed from traditional cel animation
that helps the animator create the illusion of smooth motion. It is
an easy way to complete sequence of frames at a glance and to
see how each frame flows into the frames before and after.

techniques of animation
2. Motion Cycling
Human motion such as walking, running and
flying is a repetitive action that is best represented
by a cycle.
3. Masking
A mask in a computer program is in a sense a
model of the plastic masks – it protects part of a
frame from effects of other editing tools. This
technique can be used to make an animated object move behind the
protected area. Suppose the frame of the TV is masked, so that the
scrolling text do not appear in front of the frame, but is only visible
within the TV screen.

Techniques of animation
4. Adding Sound
Background music can evoke emotions. Sounds that arise from the
actions being viewed can clarify what is happening and create an effect
of realism. We can have synchronous and asynchronous sound.
5. Flip book animation
It is a book with a series of pictures varying gradually from one page to
the next so that when the pages are turned rapidly, the pictures appear
to animate, simulating motion or some other change.
6. Rotoscoping and Bluescreening
Rotoscoping is an early animation technique which enabled animators
and video editors to trace the contour of objects on each frame of an
animation and video sequence to create a silhouette called a matte.

Rotoscoping and Bluescreening
The traced contour is then replaced by
something else to produce a special visual
effect. For example : Original Star Wars movie
which showed a glowing lightsaber effect by
creating a matte based on sticks held by actors.
Bluescreening is a technique for shooting live
action against a even coloured blue background
and then replacing the background by another
image. Blue is normally used for people but if
scene itself contains objects with blue colour,
then other colours like green and orange are
used.

Techniques of animation
7. Colour Cycling
It allows to change colour of objects by cycling through a range of
colours. The software provides smooth colour transition from
one colour to another.
8. Morphing
It is the process of smoothly interpolating between two different
images. When played back it appears
that the first image gradually and
seamlessly changes into the second
image.

Animation on the web
Typically web based animations involve computer files that must be
completely downloaded to the client machines before playback.
Limitations in use of animation on the web :
1. Bandwidth
2. Browser support
3. Differences in platforms
Streaming technology is used in order to take care of large size of files.
Once animation has been delivered to the user, the user must have the
proper helper application or plug in to display the animation. Several
formats exist today like
GIF animation (extension to GIF specification)
QuickTime Animation (based on QuickTime movie format)
Shockwave animation (based on Macromedia Director / Flash file
format etc)
Java Animation (based on Java programming language)

Macromedia Director
Macromedia's Shockwave technology for Director was one of the first
plug ins for browsers. Director is a popular 2D animation and
interactive multimedia authoring tool. To be played via the browser,
the Director movie must be saved in the Shockwave format which
uses the DCR file extension.
Macromedia Flash
Macromedia Flash animation sequences can be saved in the
Shockwave format which uses the SWF extension. SWF is an open
format which means that anyone can implement players or application
software to support SWF without paying royalties.
1. Shockwave Format

In Client Pull animation, an HTML page gives the browser
instructions to request and load another document automatically
which contains the next frame of the animation. This feature is like
a slideshow.
2. Client Pull Animation
3. Server Push Animation
A server push animation requires a CGI (common gateway
interface) script that tells the server when to automatically serve a
new document or image. So the HTML tag gives directions to a
CGI script that runs the animation instead of retrieving the image
file, itself.

3D animation
Creating 3D animation involves a number of steps :
1. Modeling – creating 3D objects from 2D shapes through lofting
(moving the object along a specific direction) and lathing
(rotation of the object about its axis to create 3D shape).
2. Surface Texture – imparts a realistic appearance to the 3D
models by applying textures over the object surface.
3. Lighting – involves placing the lights in the scene by specifying
their intensities, direction and colour. The direction of shadows
are also considered.
4. Camera – the placements determine how the scene should look
like. Movement of camera can be used to produce zooming and
panning effect.

3D animation ....
5. Animating – it involves the creation of key frames and tweening
to produce intermediate frames.
Tweening – the drawing of intermediate frames between key
frames drawn by assistant animators.
6. Rendering – it produces the final output file and needs
specifying the file type, frame size, frame rate etc.
Rendering algorithms are :
1 Ray casting algorithm
2 Shading algorithm
3 z buffer algorithm
4 Ray tracing algorithm
5 Polygon algorithm
6 Aliasing

Creating animation
For producing a one hour film, 108000 frames are required. The
computer serves as an assistant to the human animator.
Interpolations Camera Animation
Parameter Curve Editing Animating Lights and
surface properties.
Hierarchical Animation
Inverse Kinematics (IK) Shape Changes
Motion Paths