5. OVERVIEW
• What is Computer Graphics
• Basic graphics system
• History of Computer Graphics
• Graphics pipeline
• Application areas
2/15/2014
5
• Computer Graphics Programming course
6. WHAT IS GRAPHICS?
Graphics: from the Greek language → Handwriting
2/15/2014
6
• Historical meaning: general terms of handwritings, manuscripts and
reproduction techniques (copper engraving, etchings)
• Current meaning: images, diagrams, illustrations, flow charts, pixel works,
business charts, 3D’s, animations, etc
7. WHAT IS COMPUTER GRAPHICS?
The term computer graphics has been used in a broad sense to describe
"almost everything on computers that is not text or sound“
Typically, the term computer graphics refers to several different things:
2/15/2014
7
• the representation and manipulation of image data by a computer
• the various technologies used to create and manipulate images the images
so produced, and
• the sub-field of computer science which studies methods for digitally
synthesizing and manipulating visual content
8. RESEARCH FIELDS OF CG
Generative CG (1)
Design, storage and rendering of graphical models
• Object modeling based on basic graphic primitives
• Modeling of object behavior
• Rendering algorithm
• Animation
Image recognition (2)
Detection of information from images
• Recognition of lines, patterns and text
• Automated annotation of images
• Object reconstruction
Image processing (3)
Image
Description
(1)
(2)
Image
Manipulation of images
• Photoshop
8
(3)
2/15/2014
11. OUTPUT DEVICES
Video Display Devices
• Cathode Ray Tubes
• Vector scan/Random scan Display
• Raster scan Display
• color CRT monitors
• Flat panel Display
• Plasma panel Display
• LCD
• LED
Hard Copy Devices
2/15/2014
11
• printers
• Plotters
12. CONCEPTUAL FRAMEWORK FOR
INTERACTIVE GRAPHICS
Graphics library/package is intermediary between
application and display hardware (Graphics System)
2/15/2014
12
Application program maps application objects to views
(images) of those objects by calling on graphics library.
13. GRAPHICS DISPLAY HARDWARE
• Driven by display commands (move (x, y),
char(“A”) , line(x, y)…)
• Survives as “scalable vector graphics”
2/15/2014
Raster (TV, bitmap) used in
displays and laser printers
Driven by array of pixels (no semantics,
lowest form of representation)
Note “jaggies” (aliasing errors) due to
sampling continuous primitives
13
Vector (calligraphic, stroke, etc)
14. HISTORY OF CG
Ivan Sutherland (1963) – SKETCHPAD
2/15/2014
14
• Using a light pen, key pad and monitor it allowed
users create accurate design drawings
15. DISPLAY HARDWARE
vector displays
• 1963 – modified oscilloscope
• 1974 – Evans and Sutherland Picture System
raster displays
• 1975 – Evans and Sutherland frame buffer
• 1980s – cheap frame buffers bit-mapped personal
computers
• 1990s – liquid-crystal displays laptops
• 2000s – micro-mirror projectors
digital cinema
other
• head-mounted displays
• autostereoscopic displays
16. RENDERING
1960s - the visibility problem
• Roberts (1963), Appel (1967) - hidden-line algorithms
• Warnock (1969), Watkins (1970) - hidden-surface algorithms
• Sutherland (1974) - visibility = sorting
23. GRAPHICS PIPELINE
Geometry
Modelling Transformation
Transform into 3D world coordinate
system
Lighting
Simulate illumination and reflectance
Viewing Transformation
Transform into 3D camera coordinate
Clipping
Clip primitives outside camera’s view
Scan Conversion
2/15/2014
Image
Transform into 2D camera coordinate
system
Draw pixels (incl. texturing, hidden
surface…)
23
Projection
system
24. GRAPHICS PIPELINE
Geometry
Modelling Transformation
Lighting
3D models defined in their own
coordinate system (object
space)
Modeling transforms orient the
Viewing Transformation
models within a common
coordinate frame (world space)
Clipping
Projection
2/15/2014
Image
24
Scan Conversion
25. GRAPHICS PIPELINE
Geometry
Modelling Transformation
Lighting
Viewing Transformation
Vertices lit (shaded) according to
material properties, surface
properties (normal) and light
sources
Local lighting model
(Diffuse, Ambient, etc.)
Clipping
Projection
2/15/2014
Image
25
Scan Conversion
26. GRAPHICS PIPELINE
Geometry
Modelling Transformation
Maps world space to eye space
Viewing position is transformed
Lighting
to origin & direction is oriented
along some axis (usually z)
Viewing Transformation
Clipping
Projection
2/15/2014
Image
26
Scan Conversion
30. MODELING AND RENDERING
Modeling
•
•
•
•
•
Create models
Apply materials to models
Place models around scene
Place lights in scene
Place the camera
Rendering
• Take “picture” with camera
Point Light
Spot Light
Directional
Light
Ambient Light
31. CG VS. REAL
… to the streets of London
2/15/2014
31
From video game…
(Gran Turismo 5, PS)
32. SOME APPLICATIONS OF COMPUTER
GRAPHICS
Some of the application areas which make heavy use of computer
graphics are:
2/15/2014
32
• Computer aided design
• Scientific visualisation
• Films
• Games
• Virtual/Augmented Reality
NOTE: There are lots more and there is huge overlap between these
different areas
The cathode ray tube (CRT) is a vacuum tube containing an electron gun (a source of electrons) and a fluorescent screen, with internal or external means to accelerate and deflect the electron beam, used to create images in the form of light emitted from the fluorescent screen. The image may represent electrical waveforms (oscilloscope), pictures (television, computer monitor), radar targets and others.
