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

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

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

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

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

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

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

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

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

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

Morphing Linear transformation for transforming a triangle into a quadrilateral.

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

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.

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:

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