# Introduction to Computer Graphics Comp 575 - Fall 2008

Document Sample

```					 Introduction to
Computer Graphics
Comp 575 - Fall 2008

Instructor: Paul Merrell
www.cs.unc.edu/~pmerrell/comp575.html
Computer Graphics Overview
• Modeling
• Creating a geometric description of objects and
environments.
• Rendering
• Creating images from the geometric descriptions.
• Determine how light interacts with objects.
• Animation
• Putting objects and characters in motion.
• User Interaction, Virtual Reality, Visualization

2
Relationship to Other Fields

Image
Processing

Computer
Graphics
Scene
Image
Description
Computer
Vision

3
Course Overview
• Draw simple shapes
• Lines, triangles, polygons
• Compute Perspective
• Apply 3D Transformations
• Translation, rotation, scaling
• Modeling

4
Why Study Computer Graphics?
Apply technical and mathematical skills to achieve non-
technical / beautiful results.

5
What You Will NOT learn in this class
• You won’t learn how to use 3D Studio MAX,
Maya, Photoshop, or any other existing
graphics tools
• You will create your own.

6
Prerequisites
• Comp 410: Data Structures
• Math 547: Linear Algebra
• “All problems in computer graphics can be solved with
a matrix inversion.”               - Jim Blinn

7
•   Programming Assignments   -   35%
•   Final Project             -   25%
•   Midterm Exam              -   15%
•   Final Exam                -   25%

8
Textbook Suggestions

9
Applications - Movies

10
Games

11
Visualization

12
Industrial

13
Art

14
Vector Graphics

Draw (beam
turned on)

Move (beam
turned off)

• Used in early graphics systems.
• Rarely used anymore.
• Hard to draw solid regions.
15
Raster Graphics

Scan Line

Horizontal retrace

Vertical retrace

• Display is redrawn 60 times / second to avoid
• Interlaced
• Alternate between drawing even and odd scan lines.

16
Pixel

Scan Line

Raster

17
Cathode Ray Tube

1. Electron guns
2. Electron beams
3. Focusing coils
4. Deflection coils
5. Anode connection
6. Mask for separating color beams
7. Phosphor layer with red, green,
and blue zones
8. Close-up of the phosphor-coated
inner side of the screen

An electron gun produces a beam
of electrons which are deflected
magnetically onto the screen. The
beam hits phosphorescent
materials which produce visible light
when excited by electrons.

Image Courtesy of Wikipedia

18
Liquid Crystal Displays (LCDs)
• Light passes through
a vertical polarizer.
• Electricity controls
which liquid crystals
get aligned.
• Aligned liquid crystals
rotate the polarization
of the light 90o.
• The rotated light passes
through the horizontal
filter.
• When the crystal are
Image Courtesy of Wikipedia
unaligned, the light can
not pass through the
horizontal filter.

19
Colors
• 24-bit (RGB) color
•   ( 0, 0, 0) Black
•   (255, 0,     0) Red
•   ( 0, 255, 0) Green
•   ( 0, 0, 255) Blue
•   (255, 255, 0) Yellow
•   (255, 0, 255) Magenta
•   ( 0, 255, 255) Cyan
•   (255, 255, 255) White

• 256 x 256 x 256 = 16.7 million
colors

20
The Visible Spectrum
• Why are only three colors necessary?

21

```
DOCUMENT INFO
Shared By:
Categories:
Stats:
 views: 12 posted: 11/21/2008 language: English pages: 21
How are you planning on using Docstoc?