Symbolization: attribute maps

• Planimetric map example

Single-variable symbols:

• Point
• Pictograph
• Geometric
• Line
• Area

Multivariate symbols:

• Point
• Line
• Area

Cartograms

Route maps

Symbolization: statistical maps

Single-variable symbols:

• Point
• Line (variable-width, colors)
• Area
• 3-D Maps
• 2-D Maps

· Isoline maps, Shaded isolines

· Choropleth maps, another one
Choropleth maps have an inherent weakness--they involve the aggregation of data within areal units that do not correspond exactly with the underlying spatial distribution of data.
What to watch for
Know your data’s “shape”

· Dasymetric maps (http://www.wru.umt.edu/posters/People&Place.article.PDF)

· Dot maps

Multivariate symbols:

• Point
• Line (not often used, not easily effective; texture, size etc. is varies)
• Area (ratios or indexes); Isopleth – isoline showing value that can’t exist at points (eg, aggregated data, deaths per 10,000 people)

Area Cartogram

2000 Election cartogram

3-D Maps

Other useful things:

• WAGDA help files
• AV help files