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  • Demonstrating various map styles:

    • Basic chloropleth

    • Dot density

    • Graduated symbol

    • Proportional symbol

    • Flow

  • Click on images for expanded versions and further context.

Applying basic thematic map design techniques

Dent fundamentals

Cartography: Thematic Map Design by Borden D. Dent (1938–2000) remains one of the major texts in the field. These exercises laid out various methods of thematically representing data for non-reference purposes (and is an opportunity to go back to earlier work and refine them with these skills in mind.)
 
Chloropleth map

Chloropleth map

One of the more frequently encountered maps, this changes shading or coloring to represent another value.

Dot Density

Dot Density

This works much like tally marks placed within the relevant polygon shape randomly. They can more closely represent the actual locations of these points if working at a more specific scale than the map at large. (e.g. census block groups while depicting the state at large)

Graduated symbol

Graduated symbol

In this example the severity is indicated both by the size of the icon and its color intensity.

Graduated symbol alternate

Graduated symbol alternate

Using ERSI reference defaults may help indicate the subject matter via shape, but these special characters do not have convenient outlines and appear to blend in on certain backgrounds.

Proportional Symbol

Proportional Symbol

This takes the same basic symbol and modifies the size in proportion to the size of the data point it represents (automatically placed at the centroid of the respective polygon).

Flow Map

Flow Map

These can be handy for depicting linear movement between locations, whether qualitative data of sheer options or quantitative data accounting for magnitude or number.

Initial early chloropleth

Initial early chloropleth

This was an example of early output before considering current understanding of principles (or accurate math)

Revised chloropleth re: Dent

Revised chloropleth re: Dent

This takes into account a better understanding of colors that don't assail the audience but still has clear enough shading difference in the color flow that it may still be color-blind comprehensible.

Dot density (don't demean Dent)

Dot density (don't demean Dent)

This indicates how important it is to select the right means of representing information, even if working with the exact same data. The size of the dots and number of citizens they represent make some regions confusingly muddled and seems to imply physical distribution despite being randomly placed.

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