Color

1
Color Cartographic Design

• 22 May 2001

2
Color Cartographic Design

• MacEachren
• Monmonier

3
Graphic hierarchy

• Figure-ground, the visual separation of a scene
  into recognizable figures and inconspicuous
  background
• Several methods for using

4
Graphic hierarchy

• Size smaller areas tend to stand out as figure
• Value contrasts generally, dark areas as figure
  (5.01)
• Texture contracts generally, coarser as figure
  (5.02)
• Orientation more ambiguous. Generally, the
  smaller with a differently oriented fill appears
  as figure (5.03)

5
Graphic hierarchy

• Hues (contrasting) complementary colors dont
  work too well (hard to discriminate)
• Crisp edges between figure and background (5.04).
  Figure can be centrally located and closed
  (5.05).
• Or placing figure between reader and background
  (5.06).
• Or superimposition (5.07)

6
Color Use

• For multivariate data
• Hue difference can distinguish two ends of the
  scale
• Value difference can depict numerical ranges
• Plate 5.08, http//faculty.washington.edu/jnstone/
  ext/images/macplatec217-510.gif

7
Color Use

• Be careful of representing multivariate data with
  percentages
• Dont go to extremes with colors
• Try to balance both sides of colors in with
  middle saturations

8
Geographic context

• Scale and centering will control context and
  detail
• Scale is also likely to influence viewers
  attitude about importance of an environmental
  problem (p96-97)
• Small scale may make environmental problem seem
  insignificant
• Zooming in may make it seem more dire than it
  really is
• One way to combat this is to combine close-up
  with locational inset map

9
Marginal Information

• Vital for presentation maps
• Labels and titles should be carefully chosen to
  help with geographic, topical and temporal
  context
• Obvious legend headings (key or legend)
  should be avoided they add nothing

10
Marginal information

• Adequate source information is a must
• If data collection occurs over a long time, or
  map printing is different than data collection,
  these details should be noted
• MacEachren says scales, north arrows are only
  necessary when orientation is different than
  usual, or measurements are unlikely to be done

11
Marginal information

• Legends should be organized logically
• Key items of map display highlighted

12
Other things to keep in mind

• BW be careful going from screen display to bw
  report
• Be aware of actual perception
• 6 inked judged as 20
• 14 as 40
• 25 as 60
• 46 as 80
• Be careful of printing fills and textures (esp.
  many together)
• Print to your audience and use

13
Color

• Be aware of the difference between monitor
  display and printer capabilities
• On computer screens, mix of red, green and blue
  signals, called additive primaries. Three
  together equal white. RGB
• In print, ink rather than light is mixed (usually
  as overlays) cyan (blue-green), magenta
  (red-blue), and yellow. Subtractive primaries,
  color is a function of wavelengths not reflected
  by the printed page. Three together equal black.
  http//faculty.washington.edu/jnstone/ext/images/m
  onplate1-3.gif. CMYK

14
Color

• A sensory response to electromagnetic radiation
  in a narrow part of the wavelength spectrum
  between roughly 0.4-0.7 micrometers. (the
  visible band)

15
Color

• Three dimensions
• Hue, thought of as color
• Value, colors lightness or darkness, applies to
  hues and gray
• Saturation, or chroma, intensity or brilliance.
  Graytones have no saturation.

16
Use of color

• Is color being used to show difference in
  intensity, or differences in kind?
• Contrasting hues
• Good for soil, geology, vegetation, zoning, land
  use, etc.
• Not so good for differences in percentages,
  rates, values, etc.
• This is because hues have no logical ordering.
  Red vs green? Yellow vs blue?

17
Use of color

• Value differences and hues work well for
  single-sequence, part-spectral color scales,
  http//faculty.washington.edu/jnstone/ext/images/m
  onplate4-7.gif
• Common color scales for choropleth maps
• Be wary of color maps reproduced via copier or fax

18
Color

• Be wary of colors with meaning
• Red fire, warning, heat, blood, anger, courage,
  power, love, communism (incinerator example,
  http//faculty.washington.edu/jnstone/ext/images/m
  onplate4-7.gif)
• Black death, mourning, heaviness
• Blue cold, aristrocracy, faith
• White cleanliness

19
Color

• Green envy, healthy
• Yellow cowardice vs power
• Example, plate 8 http//faculty.washington.edu/jns
  tone/ext/images/monplate8-10.gif

20
Convention

• Blue water
• Green vegetation
• Red high temps
• Yellow desert
• Be aware of convention and how to use it, or
  change its use example, plate 9
  http//faculty.washington.edu/jnstone/ext/images/m
  onplate8-10.gif
• Also be aware of software defaults

21
Why use color?

• Aesthetics
• To differentiate between variables
• Increase number of features that can be portrayed
• Perceptual ordering
• Keep in mind bw can be very effective

22
More information

• MacEachren Truth in geographic
  visualization,www.geovista.psu.edu/members/maceac
  hren/index.htm (and project atwww.geovista.psu.ed
  u/members/maceachren/truthingeogvis.htm)
• Monmonier www.maxwell.syr.edu/geo/monmon.htm