Chapter 11 Animation

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Chapter 11Animation
Multimedia Systems
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Key Points

• Animation is the creation of moving pictures one
  frame at a time.
• Animation can be made using traditional methods
  and captured and digitized one frame at a time
  using a video camera or other input device.
• Drawn or painted animation can be made using a
  graphics application. Painter provides special
  support for animation using frame stacks.

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Key Points

• Animations may be rendered as QuickTime movies,
  exported as a sequence of image files or stored
  as an animated GIF.
• Layers can be used as the digital equivalent of
  cel to separate independently moving parts of an
  image.
• Sprites are objects that can be positioned
  independently. Sprite faces are used to alter
  their appearance.

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Key Points

• In key frame animation, only important frames are
  stored explicitly in-between frames are
  interpolated (tweened) from the key frames.
• Flash is designed for producing simple vector
  animations, primarily for display on the World
  Wide Web. It is organized on a time line and
  provides automated tweening.
• Easing in and easing out are used to produce more
  realistic movement than simple linear
  interpolation.
• Key frame animation is applied to bitmapped
  images in making motion graphics in programs such
  as After Effects.

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Key Points

• In 3-D animation, interpolation is applied to the
  many numerical quantities that describe a
  three-dimensional scene. It requires huge
  resources and great skill to achieve good
  results.
• Virtual reality (VR), has come to mean 3-D
  graphics that can be explored interactively. VRML
  and QuickTime VR are available formats for
  virtual reality. They come nowhere near the
  original concept of virtual reality as an
  immersive sensory experience of a synthetic
  world.

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Applications

• Animation has been used for entertainment,
  advertising, instruction, art and propaganda on
  film or video it is also employed on the World
  Wide Web and in multimedia presentations.

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Animate Means

• Animate means to bring to life
• When played back at normal film or video speeds,
  the still characters, objects, abstract shapes,
  or whatever, that have been photographed in
  sequence, appear to come to life.

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Frame Rate Requirement

• Technically, 24 frames per second.
• In practice, animation that does not require
  seamlessly smooth movement can be shot on 2s,
  which means that two frames of each drawing are
  captured rather than just one. This gives an
  effective frame rate of 12 frames per second for
  film or 15 for NTSC video.

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Cel Animation

• Those elements in a scene that might move are
  drawn on sheets of transparent material known as
  cel, and laid over a background drawn
  separately.

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Stop-Motion Animation

• Three-dimensional
• This encompasses several techniques, but all use
  miniature three-dimensional set, like stage sets,
  on which objects are moved carefully between
  shots. The objects may include articulated
  figures, whose limbs can be repositioned, or
  solid figures whose parts are replaced, or
  substituted, between shots, to produce an effect
  of gestures, walking, and so on.

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Clay Animation

• It is similar stop-motion animation, but figures
  and other objects made out of a malleable
  modeling material, such as Plasticine (????), may
  be used instead these can be manipulated between
  shots, to produce both natural movement, and
  otherwise impossible changes and transformations.

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Hybrid Forms of Animation

• Mixing cel and 3-D
• Combining animation with live footage (????),
  such as Jurassic Park.

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Captured Animation and Image sequences

• Digital Technology
• Using video camera and traditional animation
  methods together with digital technology offers
  much richer expressive possibilities to the
  animator working in digital media than purely
  computer-generated methods.

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Frame Grabbing

• For example, Premiere offers a Stop Frame
  command on its Capture menu. This causes a
  recording window to be displayed, showing the
  current view through the camera.
• You can use this to check the shot, then press a
  key to capture one frame, either to a still image
  file, or to be appended to an AVI or QuickTime
  movie sequence.
• You then change your drawing, alter the position
  of your models, or whatever, and take another
  shot.
• Frames that are unsatisfactory can be deleted.

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Ghost Image

• Premiere offers an option allows you to see the
  currently and previously captured frames
  together, to help with alignment and making the
  appropriate changes.
• Ghost image previously captured frame

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Multiple Animation Formats

• When you captured a set of frames that form a
  sequence, Premiere can save it as QuickTime
  movie or a set of sequentially numbered images
  files.

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Traditional Animation Supports

• A film scanner will even allow you to digitize
  animation made directly onto film stock.For
  example, Painter provides special support for
  animators wishing to draw or paint animations
  digitally, in the form of features that resemble
  some of the ways in which traditional animators
  work with a stack of drawings.

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Frame Stack

• A Painter frame stack is a set of images, all
  of the same dimensions and colour depth. When you
  create or open a frame stack, you are provided
  with controls for navigating through it.

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Onion Skinning

• Painter offers an option allow you to make up
  to four frames adjacent to the one you are
  currently working on visible.

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Rotoscoping

• A process of painting on existing video
  frames.For example, Painter can paint onto or
  otherwise alter original video material, which is
  one way of adding animation to live action.

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Web Page Animation File Formats(1)

• GIF Files
• GIF89as ability to store a sequence of images
  has been used to provide a cheap and cheerful
  form of small animation for Web page
  advertisements.

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Web Page Animation File Formats(2)

• GIF Shortcomings
• However, even when GIF animation is properly
  implemented and enabled, it has many
  shortcomings.
• Sound can not be added.
• Colour palette is restricted to 256.
• Images are losslessly compressed.

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QuickTime

• For animation of any duration, especially if it
  is accompanied by sound, the best result will be
  achieved using a video format, and QuickTime has
  become the standard.

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Digital Cel

• Cel in digital animation layer
• Layers allow you to create separate parts of a
  still image for example, a person and the
  background of a scene they are walking through
  so that each can be altered or moved
  independently.

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Sprite Animation

• We store a single copy of all the static layers
  and all the objects, together with a description
  of how the moving elements are transformed
  between frames.
• This form of animation, based on moving objects,
  is called sprite animation.

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Faces

• Slightly more sophisticated motion can be
  achieved by associating a set of images,
  sometimes called faces.This would be suitable to
  create a walk cycle for a humanoid character.

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Key Frame Sample

• QuickTime supports sprite tracks, which store an
  animation in the form of a key frame sample
  followed by some override samples.
• The key frame sample contains the images for all
  the faces of all the sprites used in this
  animation, and values for the spatial properties
  (position, orientation, visibility, and so on) of
  each sprite, as well as an indication of which
  face is to be displayed.

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Override Samples

• Override samples contain no image data, only new
  value for the properties of any sprites that have
  changed in any way. They can therefore be very
  small.

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Dynamically Generated Sprite Animation

• Instead of storing the changes to the properties
  of the sprites, the changed values can be
  generated dynamically by a program.

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Key Frame Animation(1)

• Breaking down complex tasks into small repetitive
  sub-tasks that could be carried by relatively
  unskilled workers
• Character design, concept art, storyboards, tests
• Trained animators creation of key frames

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In-betweening

• The intermediate frames can be drawn almost
  mechanically by in-betweeners.

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Flash

• Flash is designed for producing simple vector
  animations, primarily for display on the World
  Wide Web.
• A Flash animation is organized using a timeline,
  a graphical representation of a sequence of
  frames, similar to the timeline in video editing
  applications.

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Flashs Stage

• Flashs stage is a sub-window in which frames are
  created by arranging objects (
• vector imagesWMF, EPS, AI,
• bitmapped imagesGIF, JPEG, PNG, BMP), and which
  is also used to preview animations.

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Symbol

• Graphical objects can be stored in a library in a
  special form, called symbol, that allows them to
  be reused.
• Generating Key Frames
• To animate a symbol, a key frame is selected in
  the timeline, and the symbol is placed on the
  stage the current frame is then moved to the
  next key frame, and the symbol is moved, scaled,
  or otherwise transformed, to create the new
  frame.

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Interpolation

• In-between Frames Interpolation
• Double-clicking anywhere in the timeline between
  frames brings up a dialogue, which allows you to
  specify that the in-between frames should be
  interpolated.
• Flashs interpolation is linear.
• Flash does not offer an non-linear interpolation
  but borrows a technique from hand-made animations
  (easing in, easing out).

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Linear Interpolation
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• Two Problems with Linear Interpolation
• Unnatural movement
• Nothing really moves like this motion begins
  and ends instantaneously, with objects attaining
  their full velocity as soon as they start to
  move, and maintaining it until they stop.
• Solution using hand-made animation

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Easing In

• The object accelerate from a standstill to its
  final velocity.

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Easing Out

• The converse process of deceleration.

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Abrupt Change of Velocity

• As the velocity graph clearly shows, this will
  appear as a sudden deceleration at that point in
  the animation.
• Second problem

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Abrupt Change of Velocity

• Solution
• Non-linear Interpolation
• Using Bezier curves instead of straight lines to
  interpolate between key frames, smooth motion can
  be achieved.
• Note that we do not mean that objects should
  follow Bezier shaped paths, but that the rate at
  which their properties change should be
  interpolated using a Bezier curve.

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Motion Graphics

• Interpolation between key frames can be applied
  to bitmapped images.
• Since bitmaps do not contain identifiable
  objects, the use of layers to isolate different
  elements of an animation is essential.
• These geometrical transformations are easily
  interpolated, but since we are now concerned with
  bitmapped images, they may require resampling,
  and consequently cause a loss of image quality.

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After Effects

• Leading desktop application for animation of
  motion graphics
• Photoshop or Illustrator prepares the elements of
  an animation on a separate layer, and import the
  result into After Effects.

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Repositioning Layers

• Simplest animations
• After Effects
• Linear interpolation Figs. 11.7, 11.9
• Bezier interpolation Figs. 11.8, 11.10

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Time-varying Filters

• Motion graphics are the effects that can be
  achieved using time-varying filters on bitmapped
  images have more in common with graphic design
  than with mainstream cartoons or art animations.
• Motion graphic effects can be applied to live
  video as well as to still images.

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3D Animation

• 3D models are defined by numerical quantities.
• Object
• Position in space
• Rotation
• Surface characteristics
• Shape
• Light source
• Intensity
• Direction
• Camera
• Position
• Orientation

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• Motion paths in 3D
• Add time -gt 4D
• Render 3D animation
• Advanced shading algorithms
• Ray tracing
• A long time to process a single image

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Behavior

• A simple type of behavior
• Making one object point at another
• Camera is pointed at an object.
• Spotlight pointed at an object.
• Sunflower can be made to point at the sun
• Have one object track another
• Follow its motion at a distance
• Camera
• Behavior based on physical laws of motion

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Kinematics

• Study of the motion of bodies without reference
  to mass or force
• It is only concerned with how things can move,
  rather than what makines them do so.
• Jointed structure
• Kinematic constraints
• If upper arm is raised, lower arm and hand must
  come with it.

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Inverse Kinematics

• It is more useful to be able to position the
  object which is at end of the chain and then the
  object which is at end of chain move to
  accommodate it.
• Works backwards from effect to cause
• Poser
• Many different ways
• Minimizing the potential energy

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Bracy

• Bracy
• Basic animation by interpolation between key
  frames
• After Effects
• Animating layers with Bezier motion paths and
  velocity graphs that can be modified.
• Bracy
• Terrain modeling
• Sky, Clouds, Rainbows
• Earthquake

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Virtual Reality

• Head-mounted displays
• Data gloves track hand movements
• Haptic interfaces provide tactile feedback
• Haptics is the study of human touch and
  interaction with the external environment via
  touch.
• 'Haptic' comes from a Greek term meaning 'able to
  lay hold of'
• For flight and industrial simulation, games

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VRML

• Virtual Reality Modeling Language
• Text-based language
• VRML 2.0 added support for interactivity, via
  scripting.
• Cube, cylinder, sphere, and so on
• Textures can be mapped onto surfaces of objects
• Constructing VRML scenes by hand is a painstaking
  and error-prone business
• Using normal interactive modeling tools

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QuickTime VR

• Basic VR experience
• Panoramic movies
• 360? view of a scene
• Object movies
• Examine an object from different angles
• Hot spots
• Active areas contain links
• Can be generated from Brace
• Stitching software

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Panoramic Image
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Object Movies

• Object image array