Textbook: Slocum, T. A. 1999. Thematic Cartography and
Visualization. Prentice Hall: New Jesey.
Chapter 5: Principles of Color (See Page 83-103)
Why do we study color?
Because
it is important in cartography, especially for producing color maps.
Draw a figure showing the main forms of electromagnetic energy
spectrums?
Draw figure 5.2 on page 84 (Gamma rays,
x-rays, UV, visible light, infrared, radar, radio waves. Visible light (violet,
blue, green, yellow, orange, red)
How
human see? Light > eye (lens, retina, optic nerve) > brain
List some examples in which map is displayed in soft-copy form? See page
88
Cathod Ray Tube (CRT), Liquid Crystal
Display (LCD), Plasma displays, and electro-luminescent displays.
Describe briefly how CRT
works?
Images on CRT screen are created by firing
electrons from an electron gun at phosphors, which emit light when they are
struck (Figure 5.10, page 90). Color CRT contains three guns, normally designed
as Red-Green-Blue (RGB). CRT is based on using additive colors (RGB).
When you want to buy a CRT
(monitor, screen), what are the factors you have to consider?
- Resolution (picture element-pixel): Higher
resolution monitors are better (available resolutions
640x480, 1024x768, 1280x1024)
- Size of the
CRT (e.g. 17 inch , 21 inch)
- Number of supporting colors (16, 256,...,
16 millions)
List three disadvantages of
CRT?
1. Large size and heavy
2. Consume considerable power
3- Produce x-rays and magnetic field which are considered
health hazards
An alternative solution is LCD (flatbed
screens)
List the main hardware use for
creating hard-copy maps?
- Printers: Different types of
printers are available in the market. For example, dot matrix, electrostatic,
inkjet, thermal, and laser. Printers are based on using
subtractive colors (Cyan-Magenta-Yellow-Blak CMYK). Factors to be considered
in selecting a printer are resolution (dot per inch-dpi) e.g. 300-1200 dpi.
Resolution of printers are generally higher than CRT. A 17-inch monitor
(1024x768) displays only 75 pixels
per inch. Other factors include the number of pages per minute (speed).
- Plotters:
Different types of plotters are available in the market. For example, Pen,
electrostatic.
List the main models for specifying color?
Page 95
1. Hardware-oriented: RGB and CMYK
models
2. User-oriented: The
Hue-Saturation-Value (HSV), Munsell, and Hue-Value-Chroma (HVC)
3. CIE: International Commission on
Illumination model
Draw a figure showing the RGB
model?
See Figure 5.15 A, page 96.
List the main methods for
disseminating maps to the user?
1- Paper: Printers, plotters, and
photocopiers (xerography) can be used for small quantities. However, for large
quantities offset printing is used (lithographic plate) 2- Non-paper:
Via television (weather maps), video cassette (animated maps).
Computer-based dissemination: Maps can be
disseminated via diskette, CD-ROM, or the Internet. The problem with
computer-based maps is the fact that, colors produced at one PC may not look
typical at some other PCs. This may be due to different color setting at other
Pcs (Resolution, number of color, etc.). So it is difficult to find What You See Is What You Get (WYSIWYG).
