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					Lecture 6
  Animation
Learning Outcomes

By the end of this module, you will be able to explain:
    • captured animation
    • The meaning of image sequences
    •   Digital Cel & Sprite Animation
    •   Key Frame animation
    •   Motion graphics
    •   3-D animation
    •   Virtual reality
    •   VRML
    •   QuickTime and VR
                                   Introduction

• Animation is creating moving pictures one frame at a time,
it also means the created sequence.
• Started on 1890's
• Cel animation
          fixed background - Homer's living room
          cel, drawn on transparent paper - Homaer's image
          More complexity is created by overlaying more than one cel
          long background for creating travelling through scene
• Other means of animation
          painting directly on the film,
          sand or oil paint on glass
          chalks on paper or card
          back or front lit cut-outs
•3-D animation; stop motion animation
          moving objects carefully between shots
          malleable modelling material - clay animation
• Hybrid animation - mixing cell with 3-D, Animation + live footage (stuart little)
• All these have their digital counter parts
                               Captured Animation

• Video camera connected to computer
          Captures each frame of animation, to the hard disk, from:
                              paper, cel, 3-D Set,...
• digital version of a single frame can be stored
• This frame grabbing is provided by editing programs
          This can be used for
                              checking the shot
                              capture a frame
                                       To be stored as a still picture OR
                                       Appended to AVI or QuickTime movie
• Then next frame is grabbed
• Unsatisfactory frames can be deleted to produce the required sequence
• Digital animation can be combined with traditional to produce hybrid sequence
• QuickTime allows for storing the frames as sequentially numbered image files
          This is useful for manipulating individual images separately using image
          editors
          However, managing of a collection of image files can be very complicated
                                Captured Animation



• Scanner can be instead of camera
• Digital still camera can also be used
          In both of these cases you are allowed to:
                             Work with higher resolution images
                             Larger colour gamut
• Graphics editing program can be used to:
          make your artwork
          save your frames as individual images
• Sequence of image files imported into video editing application to create the movie

• Naming must conform with some specific conventions:
       In Premiere *.001, *.002, *.003, ..
                                Captured Animation

•Movie editing programs provide support to modify individual frames.
•For example, Painter:

    •Supports frame stack--a set of images with same dimensions & colour depth
    •Works on 4 ghost images
                                  Captured Animation

• Computer programs help the animator in:
         recording sequence of operations as a macro or script to:
                           draw repeated elements
                           apply filters to many frames
         • Also, framestack can be used to create animation by progressively altering
         one single image
• Rotoscoping can also be implemented to:
    create animation that accurately reproduce natural movement. (Any example?)
• GIF animations are implemented by storing many frames in a single file
• Painter, Premiere and Flash can produce animated GIF files
    Also ImageReady and Fireworks can be used.

• GIF file is played from the HD by the CPU
    Require no plug-in
    Sound not possible, only 256 colours and little compression.
    Not for realistic use, but for stylised changing images (Example?)
    Worst animations appeared due to ease of production.

• QuickTime using video format is the standard for animations with sound
                        Digital Cell & Sprite Animation



• Layers allow to create separate parts of a still image
          A person
          And a background
• Animation can be created by keeping the background and changing the person
• Addition of more static images produces depth illusion
• The moving object may only need reposition or transformation
          Globe moving in stars background
• This is called Sprite animation
          Objects are called Sprites
          faces can also be used - for creating walking man
• QuickTime support sprite tracks
          key frame samples - most of the data
          override samples - changed properties
                            can be generated by a program
                            properties can be changed by user interaction - games
                                    Key Frame Animation

• Most powerful web animation is Shockwave Flash - supports vector & bitmapped graphics
• Interpolations (tweenings in Flash)) are more easily applied for vector graphics
          Flash - uses timeline
          Flash uses stage (a sub-window) used to:
                               Create frames from objects
                                          objects are hand drawn OR
                                          pictures - jpg or png
                               preview animations
                               Objects can be stored in a library as symbols
                                          Transformations can be applied on these symbols

          Flash contains vector graphics drawing toolbox

          Objects can be moved (motion tweening) along a path (of any shape) drawn on a
          layer
          Flash supports shape tweening and complex animations

          Flash uses easing in an easing out
          Beizer curves can be used to ease abrupt velocity change
• Flash also support scripting language (ActionScript) for user interaction

• Native format of flash files is SWF (vector animation format) which contains:
          Definitions of symbols, and
          Control Items; instructions
                                  Motion Graphics



• Simplest Animations can be made by repositioning layers of bitmapped images
(cell animation) by:
          Dragging them
          Entering coordinates and interpolating between them
          Combining layers and adding effects and time varying filters

• AfterEffects supports both interpolations:
         Linear and
         Beizer
• Temporal Interpolation is set of value graph for the property
         The figure illustrate the frog velocity
         To prevent gliding effect - separate parts of the frog should be put on
         separate layers
                                  Motion Graphics




•The figure shows time-varying Guassian blur in conjunction with varying brightness




•Beizer interpolation is used for smooth fade-up
•Adding temporal dimension to objects introduces the application of new effects
                              3-D Animation

• 3-D models are a collection of numerical quantities
        These quantities represent Object's:
                           Position in space
                           Rotation
                           surface characteristics
                           Shape
        Numbers also represent:
                           Light source:
                                     intensity
                                     direction
                           Camera:
                                     position
                                     orientation
        Therefore to animate in 3-D you have to:
                           Setup & render 1-st frame
                           make changes to parameters
                           render the next frame
                           You need interpolation to do these calculations
                           3-D motion paths are Beizer splines
                                 3-D Animation

• Simple 3-D animations are easy to generate with dedicated software
• Realistic 3-D animations require huge resources of:
         CPU power
         memory
         software
         Skilled personnel
• 3 factors make 3-D animation hard:
         Human difficulty in visualising 3-D objects
                  Therefore 4-D(also time) has to be visualised in 2-D screens
         3-D rendering (ray-tracing) requires immense processing even for single frame
         You have to do all that for at least 12 frames/second
• Behaviours of objects used in animation:
         one object points to another
         one object tracks another
         following laws of physics - falling objects, acceleration, speed,..
                               3-D Animation
• Kinematics:
         motion study without reference to mass or force - human arm movement
• Kinematics constraints - certain ways of moving the arm
• Inverse Kinematics- moving foot to a step; work from step position
         from effect to cause
         Does not work in straightforward manner - how many ways can you touch
         you nose tip with your 1-st finger
• Some 3-D animations can be done effectively using simple interpolation of object
properties
         Most successful -
                            Animation produced by interpolating between key frames
                            Similar to after effects
                            Animating a camera to obtain 'fly through'
                            Animating a camera to follow objects motion
                            Examples
                                      terrain modelling
                                      Moving clouds
                                      Storm gathering - through colour and density
             manipulation
                                      Rainbows - appear & fade
                                      fog swirl & disappear
                                        Virtual Reality

•   Head-mounted dsiaplays
•   data gloves
•   High cost of the hardware limited its usage
•   Two VR technologies deserve mentionin
       •VRML
            •Created 1994; text base language
            •allows 3-D objects & scenes to be described by a programming language
            VRML 1.0 embedded hyperlinks in scenes
            VRML 2.0 supports interactivity (ISO standard in 1997)
                       Specifying objects in terms of geometry - Cylinder, cube,..
                       Scenes can be lit in different ways
                       Object described by a grid constructed from points
                       It is more than modeller
                                  Provides interactivity
                                  incorporation in the web
                                  The way objects are displayed
                                  Once VRML file is downloaded the plug-in (or
                                  dedicated Browser), VRML allows the user to explore
                                  the 3-D world it describes
                                  VRML must be rendered in real-time using 3-D accelerator
                                   cards
                          QuickTime VR - QTVR



• Basic VR experience
• Two types of VR movies:
         Panoramic movies - 360 degrees of the scene
         Object movies - examine object from different angles
         Both contain hot spots -Active areas (links)
                   go through door
         Generated from Bryce
         made from photos
         special rotating rig for camera
• Productions can be combines with audio & video
• can be viewed by QuickTime software
• VR and QTVR implements VR with out special interface expensive devices

				
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