EECE 478 - University of British Columbia



EECE 478

Lecture notes for January 3, 2001

A Roadmap to the Course

1. Introduction

- 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

10. Communication for Entertainment

Advances in Computer Graphics

|1960’s and 70’s |1980’s |1990’s |

|Expensive specialized hardware (mainframes)|Cheaper/faster more accessible hardware |Even faster/cheaper, parallel hardware (PCs and|

|Specialized software |(mainframe to PC) |Workstations) |

|Light pen, keyboard |High-level, device independent graphics |Graphics and GUI |

| |Tablets, mouse, keyboard |Dataglove, head mounted display |

|Real-Time | |Real-Time |

|Moving wireframe | |Moving polygons |

|10000’s of vectors | |100000’s triangles |

|No hidden edges | |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 |Set of horizontal scan lines (raster) |

|Single Phosphor (monochrome) |1 or 3 (colour) beams |

|Display list |refresh/frame buffer |

|No aliasing |Aliasing |

|Wireframe |Filled polygons |

| | |

|[pic] |[pic] |

| | |

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

[pic]

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.

[pic] [pic]

Translation Rotation

Clipping

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

[pic][pic]

Before Clipping After Clipping

Depth Sorting

[pic]

Curve Generation

Original Step 1 Step2

[pic] [pic] [pic]

The operation above can be represented by mathematical transformation matrix.

Colour Models

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

[pic]

RGB Model

[pic]

HSV Model

Other Topics

1. 2D/3D Viewing

2. Texture Mapping

3. Image Morphing

….etc

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