Computer Graphics

Computer Graphics

An Introduction

Computer Graphics

26/9/2008 Lecture 1 2

What’s this course all about?

We will cover…

Graphics programming and algorithms

Graphics data structures

Colour and human vision

Applied geometry, modelling and rendering

Computer Graphics

26/9/2008 Lecture 1 3

Computer Graphics is about animation (films)

Major driving force now

Computer Graphics

26/9/2008 Lecture 1 4

Games are very important in Computer Graphics

Computer Graphics

26/9/2008 Lecture 1 5

Medical Imaging is another driving force

Much financial support

Promotes linking of graphics with video, scans, etc.

Computer Graphics

26/9/2008 Lecture 1 6

Computer Aided Design too

Computer Graphics

26/9/2008 Lecture 1 7

Scientific VisualisationTo view below and above our visual range

Computer Graphics

26/9/2008 Lecture 1 8

First Lecture

• The graphics processes– What we will cover on this course

• Some definitions– Fundamental units we use in these processes

• Raster graphics implications

• Course support resources

Computer Graphics

26/9/2008 Lecture 1 9

Graphics Pipelines

• Graphics processes generally execute sequentially

• Typical ‘pipeline’ model

• There are two ‘graphics’ pipelines– The Geometry or 3D pipeline– The Imaging or 2D pipeline

Computer Graphics

26/9/2008 Lecture 1 10

Geometry Pipeline

Animation/Interaction : time

Modeling: shapes

Shading: reflection and lighting

Transformation: viewing

Hidden Surface Elimination Imaging

Pipeline

Computer Graphics

26/9/2008 Lecture 1 11

Imaging Pipeline

Rasterization and Sampling

Texture Mapping

Image Composition

Intensity and Colour Quantization

Geometry

Framebuffer/Display

Pipeline

Computer Graphics

26/9/2008 Lecture 1 12

An example thro’ the pipeline…

The scene we are trying to represent:

Images courtesy of Picture Inc.

Computer Graphics

26/9/2008 Lecture 1 13

Wireframe model – Orthographic views

Computer Graphics

26/9/2008 Lecture 1 14

Perspective View

Computer Graphics

26/9/2008 Lecture 1 15

Depth Cue

Computer Graphics

26/9/2008 Lecture 1 16

Hidden Line Removal – add colour

Computer Graphics

26/9/2008 Lecture 1 17

Constant Shading - Ambient

Computer Graphics

26/9/2008 Lecture 1 18

Faceted Shading - Flat

Computer Graphics

26/9/2008 Lecture 1 19

Gouraud shading, no specular highlights

Computer Graphics

26/9/2008 Lecture 1 20

Specular highlights added

Computer Graphics

26/9/2008 Lecture 1 21

Phong shading

Computer Graphics

26/9/2008 Lecture 1 22

Texture mapping

Computer Graphics

26/9/2008 Lecture 1 23

Texture mapping

Computer Graphics

26/9/2008 Lecture 1 24

Reflections, shadows & Bump mapping

Computer Graphics

26/9/2008 Lecture 1 25

Graphics Definitions

• Point– a location in space, 2D or 3D– sometimes denotes one pixel

• Line– straight path connecting two points– infinitesimal width, consistent density– beginning and end on points

Computer Graphics

26/9/2008 Lecture 1 26

Graphics Definitions• Vertex

– point in 3D

• Edge– line in 3D connecting two vertices

• Polygon/Face/Facet– arbitrary shape formed by connected vertices– fundamental unit of 3D computer graphics

Computer Graphics

26/9/2008 Lecture 1 27

Graphics Definitions

• Raster– derived from TV systems for a row of pixels– commonly referred to as a scanline– does influence algorithms – reducing memory

requirements, parallelism, etc.– is the derivation of rasterization, scan-line

algorithms

Computer Graphics

26/9/2008 Lecture 1 28

Course support resources

• Graphics course website– lecture material,– lecture log with general summary and

recommended reading,– Links to support material for lectures and

projects,– Practical description and resources

Computer Graphics

26/9/2008 Lecture 1 29

Summary

• The course is about algorithms, not applications

• Graphics execution is a pipelined approach

• Most of the steps introduced with an example

• Basic definitions presented

• Some support resources indicated