Multimedia object types: animation

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Multimedia object typesanimation

• ISMT multimediaDr Vojislav B Miic

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Animation

• Technically, similar to video a sequence of
  still images
• Images created artificially, as opposed to video
  (which presents something happening in the real
  world, maybe retouched)
• Why? Because it is a good (and sometimes less
  expensive) way to show/say some things

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What we are going to talk about?

• Cel (and flipbook) animation
• Sprite, path, vector animation
• Key frames and tweening
• Character animation
• 2D vs. 3D
• and other things

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Flipbook animation

• displaying a sequence of graphic files(e.g., a
  slide show)
• problem takes too much time (especially over the
  Internet)
• solution some form of compression (we will
  discuss this in more detail later)
• compression techniques are usually proprietary
  (different type of images!)

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Cel animation

• animation created by a sequence of still images
  (as always)
• different characters, objects, backgrounds
  overlaid to obtain the final image
• final image is shot frame by frame
• changes are made only to objects which move
• multiplan camera (Disney) distance between
  layers in order to create an illusion of depth

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Sprites and Paths

• sprite a part of the animation which moves
  independently of the rest
• anything can be a sprite ball, animal, human,
• a sprite can be attached to a path (or vice
  versa), so that successive sprite positions are
  located on a path
• sprite can animate in-place, or move along a
  path, or both

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Splines and Vectors

• paths can be linear, but that is unrealistic
• more often, paths follow a spline curve
• watch for gravity!
• example mixed feelings
• sprites can be describedas raster objects

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Key frames

• most important frames are drawn firstkey frames
• establish the main dramatic poses,
• define the flow of actions, and
• create the overall graphic style of the animation

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Tweening

• tweeningframes areinsertedbetweenthe key
  frames
• computer can do much of the tedious work

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Motion interpolation

• Motion along an arbitrary line
• Computer performs the interpolation
• Special effects (rotation, resizing) can be
  specified along the line

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Character animation

• often the trickiest part many simultaneous
  movements involved
• faces are very difficult to animate
• sometimescutouts areused forbody parts

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Other design effects

• ease-in and ease-out
• velocity curves
• line-of-action
• secondary action and overlapping action
• follow-through
• hierarchical motion
• exaggeration

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Anticipation, action, reaction

• Action/reaction is often anticipated before it
  actually happens
• Sometimes aided by showing small movements
  immediately before the action
• Reaction-recovery small movements in the
  opposite direction immediately after the action
• Fake the action itself is not shown, only what
  happens before and immediately after

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Kinematics

• (in mechanical engineering) study of motion of
  rigid objects and structures
• (in motion picture technology) study of motion of
  (rigid) objects and structures with joints
• examples men (objects) walking, running,falling
  down or apart
• inverse kinematics calculating the motion form
  predefined key positions, under the given set of
  constraints

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Morphing

• transformation of one image into another
• very popular a few years ago
• a number of key points is set on both images
• actual transformation is calculated on the basis
  of transformation (in both position and color) of
  key points
• more key points more intermediate steps
  smoother transformation

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Some rules to be obeyed
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Animated GIFs

• a sequence of still images (actually GIF images
  according to GIF89a standard), packed for the
  Internet
• suitable for simple animations
• small size short loading time
• several tools available (including one from
  Microsoft)

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Macromedia Flash

• Quickly becoming de facto standard
• Compact export format, players
• Ability to incorporate raster images as well as
  vector objects
• Powerful 2D motion effects
• Hotspots to support interactivity
• More on Flash in the lab sessions

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2D vs. 3D

• our perception of the world is three-dimensional
• 3D effects improve visual appearance
• 3D special effects can be added to 2D images
  (most drawing/painting programs can do it)
• 3D images can be generated from appropriate scene
  setups
• but sophisticated applications are required

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3D effects

• adding depth to 2D images
• effects like
• extruding
• shadows
• highlights
• embossing
• texturing
• special lighting effects

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Genuine 3D

• genuine 3D worlds rendered into 2D images
• tasks in creating 3D a brief overview according
  to Pixar

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Step 1 Creating Storyboards

• detailed storyboard drawings are created as the
  blueprint for the action and dialog
• there can be as many as 3 to 4 thousand such
  drawings for a feature-length movie (which comes
  to about onedrawing everytwo seconds or so)
• they are revisedmany times duringthe
  creativedevelopment process

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Step 2 Modeling

• specialized animation software is used to create
  three-dimensional computer models of characters,
  props, and sets
• computer models describe the shape of the object
  as well as themotion controls thatthe animators
  use tocreate movementand expressions

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Step 3 Animation

• specialized animation software allows animators
  to choreograph the motion in each scene by
  defining key frames or poses
• computer automatically creates the "in-between"
  frames
• animators neitherdraw, nor paint thescenes, as
  is requiredin traditionalanimation process

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Step 4

• surface characteristics, including textures,
  finishes and colors, are added to every object in
  the scene
• textures can simulate a wide variety of
  appearances
• textures may be 2Dimages or proceduralalgorithms
  
• additional propertiesreflectivity,transparency
  

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Step 5

• Using "digital lights," every scene is lit in
  much the same manner as stage lighting
• Key, fill and bounce lights and room ambience are
  all defined and used to enhance the mood and
  emotion of each scene

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Lighting is the key

• Key light the brightest
• Fill light opposite the key light, reduces
  contrast and shadows
• Back light reduces shadows, separates the
  subject from the background
• Powder your nose

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Step 6 Rendering

• rendering software (Pixar's proprietary
  RenderMan) "draws" the finished image by
  computing every pixel of the image from the
  model, animation, shading, and lighting
  information
• once rendered, finalimages aretransferred to
  film,video, or CD-ROM

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Summary

• Animation is often the simplest way to accomplish
  motion
• If you want to go beyond what Flash can offer, be
  ready for surprises