1. Prepared by: Engr . Syed Atir Iftikhar
Animation
Prepared by: Engr . Syed Atir Iftikhar

2. Introduction to Computer Animation
Time sequence of visual changes in a scene.
Animation has historically been produced in 2 ways.
First, by artist creating a succession of cartoon frames, which are then combine into a film
Second, by using physical model, E.g King Kong, which are positioned, image is recorded, then the model is moved, the next image is recorded, and this process is continued

3. Computer Animation
Simple Animation, this might be just moving the camera or the relative motion of rigid bodies in the scene
It is used in Visualization to show the time dependent behavior of complex systems
A major part of animation is motion control (level of abstraction).
A low level system requires the animator to precisely specify each detail of motion control techniques
A high level system would allow them to use more general or abstract methods

4. Types of Animation System
Scripting Systems
Procedural Animation
Representational Animation
Stochastic Animation
Behavior animation

5. Types of Animation System
Scripting Systems
Earliest type of motion control system.
The animator writes a script in the animation language.
Thus, the user must learn this language and the system is not interactive.
Procedural Animation
describes the motion algorithmically
express animation as a function of small number of parameters
Procedures that use laws of physics or animated generated methods
E.g. throwing a ball which hits another object and causes the second object to move

6. Types of Animation System
Representational Animation
This allow an object to change its shape during the animation
Stochastic Animation
Used to control groups of objects
E.g. fireworks, fire, water falls etc
Behavior Animation
Objects or actors are given rules about how they react to their movements
E.g. schools of fish/birds where each individual behaves according to a set of rules defined by the animator

7. Low Level Motion Control
Key-framing
Describe motion of objects as a function of time from a set of key object positions.
In short, compute the in-between frames.
Key-frame systems were developed by classical animator such as Walt Disney.
Keyframe Interpolation
The interpolation method that a keyframe is set to determines how settings are animated from one keyframe to the next.
There are three possible types of interpolation:
Smooth  more realistic
Linear  constant rate of change from 1 keyframe to the other
Constant  static, no change in animation

8. Key Framing Systems - Morphing
Transformation of object shape from 1 form to another is Morphing.
Given the 2 key-frames for an object transformation,
we first adjust the object specification
So that the number of polygon edges (or number of vertices) is the same for the two frames

9. Morphing
E.g. A straight line segment in key-frame k is transformed into 2 line segments in key-frame k+1
Since k+1 has an extra vertex, we add a vertex b/w vertices 1 & 2 (to balance the number of vertices)
Simple problem: linear interpolation between first two points assuming
x(t) = xo(1-t) + x1t

10. Morphing
Linear interpolation for transforming a line segment in key-frame k into 2 connected line segments in key-frame k+1

11. Morphing
Linear transformation for transforming a triangle into a quadrilateral.

12. Kinematics
It describes the motion of points, bodies (objects) and systems of bodies (groups of objects) without consideration of the causes of motion

13. Kinematics Forward Kinematic
Describes the positions of the body parts as a function of the joint angles.
Posing a character
knee wrist arm
Inverse Kinematic
common use is making sure that game characters connect physically to the world,
E.g. such as feet landing firmly on top of terrain.

14. Skeleton Hierarchy The characters in a game have skeletons.:
Skeleton Hierarchy
The characters in a game have skeletons.
Similar to our own skeleton, this is a hidden series of objects that connect with and move in relation to each other.
Using a technique called parenting, a target object (the child) is assigned to another object (the parent).
Every time the parent object moves, the child object will follow according to the attributes assigned to it.
A complete hierarchy can be created with objects that have children and parents. Here's an example for a human character:

15. Skeleton Hierarchy The closeup shows the skeleton's arm.
The finger objects are children to the hand object, which in turn is a child to the forearm object