Geography Reference
In-Depth Information
COMMUNICATION AND GEOGRAPHIC UNDERSTANDING
GI and Cartography Issues
Chapter 3
GI and Cartography Issues
“All maps lie” is a statement that ref lects on the necessity of relying on
abstraction in order to communicate with maps. After considering geo-
graphic information and maps in terms of geographic representation, carto-
graphic representation, accuracy, and quality, it's clear that a map's lie is dis-
putable. Some maps overtly distort things and events and hold little
similarity with the world they represent. Other maps, by simplistically apply-
ing conventions and frameworks, may greatly but unintentionally distort
things to an even greater extent. Choices made in the geographic representa-
tion and cartographic representation of geographic information and maps
determine accuracy and quality. Whether there is “too much” distortion
comes down to a map's fitness-for-use.
This chapter examines the fundamental choices of geographic represen-
tations and cartographic representations covering the key properties: projec-
tions, scale, symbolization, and color. It lays the foundation for more
detailed examinations of cartographic and geographic information princi-
ples in the following chapters. These chapters focus on these fundamental
choices with the goal of introducing their application and significance for
geographic information and maps.
From a Round to a Flat Surface: Projections
Representing and communicating geographic information and maps on f lat
surfaces (screens or paper) requires transforming three-dimensional loca-
tions from the earth to two-dimensional locations on a f lat plane, which can
either be a two-dimensional (2-D) coordinate system (in the case of geo-
graphic information) or a piece of paper (in the case of a map). Projections
for large areas usually use a simple sphere; for smaller areas, where accuracy
gains in importance, the projection uses an ellipsoid which locally corre-
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