Lecture 5: 11/5/1435 Computer Animation Lecturer/ Kawther Abas CS- 375 Graphics and Human Computer Interaction

Computer Animation In its simplest form, computer animation simply mean:  using a standard renderer to produce consecutive frames  wherein the animation consists of relative movement between rigid bodies and possibly movement of the view point or virtual camera Or Animation is simply defined as the sequencing of a series of static images to generate the illusion of movement

Two main categories Computer-assisted animation  2D & 2 1/2 D  Inbetweening  Inking, virtual camera, managing data, etc Computer generated animation  Low level techniques  Precisely specifying motion  High level techniques  Describe general motion behavior

History of Computer Animation 1974: Hunger by Rene Jodoin and Peter Foldes  2.5D system, object interpolation Computer animation is divided into three fields.Entertainment.Engineering.Science

History of Film & Video Companies  Mathematical Applications Group, Inc. (MAGI)  Information International Inc. (III, or Triple-I)  Digital Production  Digital Effects  Image West  Robert Abel and Associates  Cranston-Csuri.

Character Animation Control motion of articulated limbs Skeletal-muscle-skin models Facial animation Representation and Animation of surface detail  Hair  Clothes

Steps of a simple computer animation 1. Creating animation sequences  object definition  path specification (for an object or a camera)  key frames  in-betweening  2. Displaying the sequences  raster animation  colour-table animation

Displaying animation sequences Movies work by fooling our eyes A sequence of static images presented in a quick succession appears as continuous flow

Why animation works The eye cannot register images faster than approximately 50 frames per second (30 is just about adequate) If a gap in the projection occurs, the eye seems to perform spatial interpolation over the gap

Displaying animation sequences To achieve smooth animation, a sequence of images (frames) have to be presented on a screen with the speed of at least 30 per second Animations frames can be  pre-computed in advance and pre-loaded in memory  computed in real time (e.g. movement of the cursor)

Keyframing Keyframe systems take their name from the traditional hierarchical production system first developed by Walt Disney Skilled animators would design or choreograph a particular sequence by drawing frames that established the animation - the so-called keyframes The production of the complete sequence was then passed on to less skilled artists who used the keyframes to produce ‘in-between’ frames

Keyframing The emulation of this system by the computer, whereby interpolation replaces the inbetween artist, was one of the first computer animation tools to be developed. This technique was quickly generalized to allow for the interpolation of any parameter affecting the motion Care must be taken when parameterizing the system, since interpolating naive, semantically inappropriate parameters can yield inferior motion

Camera Placements Strive to use a series of shots from different camera angles that rarely last longer than a few seconds. Try to find interesting camera angles rather than straight-on. 13

Visual Focus Always ask yourself, “Where do I expect my view to look?” Arrange your visual elements and camera so your viewers easily understand where to look. In most situations, do not position the subject centrally in the picture. Use the rule of thirds by visually dividing the width and height of the frame into three parts. Try to put the most important object at one of the intersections (top left, top right, bottom left, bottom right). 14