Computer Graphics

1
Computer Graphics

• Introduction

2
What is Computer Graphics?

• Computer applications that create 2-dimensional
  (2D) images
• 2D Images create using computers
• Wait!!!
• What about 3D?
• 3D images are actually displayed as 2D projections

3
Uses of CG

• User interfaces
• Business graphics
• Science
• Cartography
• Medical imaging
• Manufacturing
• Multimedia/Education
• Entertainment

4
User interfaces

• Interactive
• Visual feedback
• Graphical User Interface (GUI)
• Windows
• Buttons
• Sliders
• List boxes

5
Business

• Turns data into information
• Used to facilitate decision making
• Charts and graphs
• Pie
• Bar
• Scatter plots

6
Science

• Scientific visualization
• Allows users to access the information in very
  large data sets via visual cues
• Visual cues
• Color
• Shape
• Motion

7
Manufacturing

• Computer-Aided Design (CAD)
• Computer-Aided Manufacturing (CAM)
• Drafting programs
• Often include the ability to simulate real-life
  conditions in a virtual world

8
Multimedia/Education

• Computer-Aided Instruction (CAI)
• Computer-Mediated Instruction (CMI)
• Uses visual tools to reinforce/supplement
  text-based content

9
Entertainment
10
History 1950s

• Output via Teletypes, lineprinters, etc.
• Cathode Ray Tube (CRT)
• Whirlwind Computer, MIT (1950)

11
History 1960s

• Vector graphics
• Interactive graphics
• Sketchpad, Ivan Sutherland (1963)
• Doctoral thesis
• Utilized lightpen for interaction

12
History 1960s

• CAD/CAM
• General Motors DAC system
• Itek Digitek system

13
History 1980s

• Personal computers
• Raster graphics
• Bitmap image - displayed as rows and columns of
  colored dots
• Pixel (Pel) -
• picture element
• smallest directly addressable element in a raster

14
History 1980s

• GUIs
• Windowing systems
• Interactive devices
• trackball
• mouse

15
Output devices

• Mid-60s - Vector displays
• random scan - draw lines point-to-point
• refresh - image is redrawn 30 times per second
• display buffer - holds drawing instruction data
• Early-70s - Raster displays
• scan lines - rows of pixels drawn in a specific
  order
• frame buffer - holds pixel data

16
Standards

• Graphical Kernel System (GKS)
• Programmers Hierarchical Interactive Graphics
  System (PHIGS)
• OpenGL

17
Overview
Application model
Application program
Graphics system

• Application model - represents the data or
  objects to be rendered
• Application program - creates, reads from and
  writes to the model
• Graphics system - performs I/O transformations

18
Check-up!

• State at least three uses of computer graphics
  mentioned in class.
• What is a Pixel?
• What is vector graphics? Raster graphics?
• State at least two graphics standards mentioned
  in class.