A roadmap to the Course

Lecture notes for January 3, 2001

A Roadmap to the Course

- computer graphics system (Hardware/Software) and applications

- vector versus raster architecture and clipping

- mathematics transformation

- aliasing / antiliasing

2. 3D viewing

3. Lighting and Shading

4. Colour

5. Graphical User Interface (GUI)

6. Moving targets (objects), animation

7. other topics
Visualization : The principal purpose for using graphics
1. Graphical User Interfaces (GUIs)

windows, icons, direct manipulation interfaces

2. Viewing, analyzing and iterating with data 2D, 3D and N-Dimensional

3. Scientific Visualization

4. Engineering and Architectural design systems CAD

5. Medical images and models

6. Cartography and GIS (Geographic Information System)

7. Graphic Design

8. Communication for Advertising

9. Communication for Education

Advances in Computer Graphics

1960’s and 70’s	1980’s	1990’s
Expensive specialized hardware (mainframes) Specialized software Light pen, keyboard	Cheaper/faster more accessible hardware (mainframe to PC) High-level, device independent graphics Tablets, mouse, keyboard	Even faster/cheaper, parallel hardware (PCs and Workstations) Graphics and GUI Dataglove, head mounted display
Real-Time Moving wireframe 10000’s of vectors No hidden edges		Real-Time Moving polygons 100000’s triangles Gouraud/Phong Shaded Hidden Surface Effects(texture mapping, antialiasing, fog,….)

Overview of Computer Graphics and Applications
Related Fields:

• 
  Image processing and display
  
• 
  Video
  
• 
  Computer Vision
  
• 
  Human-machine interaction (HMI or HCI : human-computer interaction)
  
• 
  Multimedia
  
• 
  Geographic information systems
  

Image Characteristics

• 
  2D versus 3D
  
• 
  Line drawing / Wireframe
  
• 
  Flat Shaded
  
• 
  Shaded
  
• 
  Shadows
  
• 
  Reflection and Transparency
  

Systems That Depend on Computer Graphics

• 
  Multimedia Systems
  
• 
  Animation
  
• 
  Computer Games
  
• 
  Virtual Reality
  

Vector versus Raster Display Technology

Vector (1960’s, 70’s, 80’s)	Raster (1980’s, 90’s)
Vector, stroke, line drawing Single Phosphor (monochrome) Display list No aliasing Wireframe	Set of horizontal scan lines (raster) 1 or 3 (colour) beams refresh/frame buffer Aliasing Filled polygons

Computer Graphics Versus Image Processing

• 
  Computer Graphics is for pictorial synthesis of real or imaginary objects from their computer-based models
  
• 
  Image Processing operations are used to help synthesize the image of the model. It deals with the analysis of pictures, on the reconstruction of the model of objects from their pictures.
  
• 
  Image Processing is for enhancement, restoration, coding, pattern recognition, computer vision, etc.
  

Aliasing problem

The jaggles or aliasing on the picture on the left can become less noticeable by increasing the resolution. Even the one on the righ has twice as many jaggles as the original one, but the jaggles are much less noticeable. The disadvantage is that it is expensive since 4x the memory and extra time for scan conversion

Mathematics Transformation (2D or 3D)

The most common and primitive mathematics transformation are : translation, scaling, rotation, shearing.

Translation Rotation

Clipping

2D and 3D clipping – to clip away any part outside a viewport


Before Clipping After Clipping

Depth Sorting

Curve Generation

Original Step 1 Step2

The operation above can be represented by mathematical transformation matrix.

Colour Models

There are many colour models, like RGB, CMYK, HSV, etc.

RGB Model

HSV Model

Other Topics

1. 
   2D/3D Viewing
   
2. 
   Texture Mapping
   
3. 
   Image Morphing
   

….etc

Directory: ~saifz -> eece478
eece478 -> Note: All the transformation matrices in this assignment are supposed to work on column vectors

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