Maps and GIS

Displaying Data

Cartography

Cartography is the art and science of organizing and communicating geographic information. As we discussed at the beginning of the class, cartographers developed a symbology to describe real-world features on maps. These symbols can be distilled down to 3 general feature types: points (or some kind of icon), lines, and polygons. Early maps were prepared to describe hunting/gathering areas, battle plans, and territories.

Cartographers also developed stylistic ways of communicating ideas on maps. Such styles include quantitative and qualitative ways of describing features. For example, on a thematic map describing population cartographers can draw icons that represent the number of people in a county (e.g., one person-like icon represents 1000 people), or they can color counties according to population ranges (e.g., graduated colors).

Relationship between graphic parameters and their abilities:

Size	Quantitative
Density	Quantitative
Texture	Quantitative
Color	Qualitative
Shape	Qualitative
Orientation	Qualitative

Remember the data scales we used. Can you envision a way to use the above graphic parameters to depict the intended data scale?

Graphic elements and parameters

The most basic graphic elements include points, lines, and polygons. We can adjust their size, shape, pattern, and color to communicate different ideas. Variations in pattern include orientation (e.g., directionality), arrangement (e.g., shadowing), and texture (e.g., density of the pattern). Variations in color are based on hue, saturation, and value. This is known as the HSV model.

Design considerations

Who is your audience? What idea are you trying to convey? Why are you telling the audience this? How will the audience be viewing the map? The answers to these questions may determine what goes on the map and how it is displayed.

You must also balance all the elements on your map.

Items closer to the visual center (VC) should be heavier
Items further from the VC should be lighter
Isolated items heavier
Items at top heavier
Do not put anything too close to the bottom of the map

Finally, the basis for distinguishing objects is contrast. Contrast includes the placement, size, and color of objects.

Foreground – warmer colors
Background – cooler colors
Most people like pure hues

Essential map elements and Sheet furniture

Map composition
Title
Scale
North arrow
Legend
Date
Projection and datum
Cartographer’s name
Information about data used in the map composition

Assignment(s):

Expand your suitability analysis to consider the larger, regional or neighborhood level, context. For example, identify the influence of the proposed project on municipal services. This may or may not require use of GIS, depending on the data available and what you choose to investigate.
Draft an appendix to your previous memo describing the potential impacts of the proposed projects (at the site you chose) at the larger scale. The memo should include the community factors you analyzed, your method(s) of analysis, and how this supports (hopefully) your site selection.
Prepare a 10-minute presentation with supporting documentation, to be given next week, which describes the results of your analysis.