Geography Reference
In-Depth Information
Choices and Geographic Representation
The choices involved with creating geographic representation are wide-rang-
ing and often elusive because conventional ways of understanding geogra-
phy lump them together. Further, some of the choices have direct and obvi-
ous consequences for cartographic representation and communication, but
the consequences of others are hard to pin down. For each of the choices
identified here, you will find an indication of how it is relevant (highlighted
in italics) to the example of river f looding we examined earlier in the chap-
ter. These choices are discussed in more detail in Chapter 3 and the follow-
ing chapters.
Data collection
To represent a thing or event, data must be col-
lected. The collected data must offer sufficient geo-
graphic, attribute, and temporal detail for the
intended purposes and uses.
How are the measurements of water height and river bank
elevation made?
Data updates
Missing roads, changed land uses, and so on can
impair reliable communication with geographic infor-
mation and maps. The choice to use out-of-date
source materials can gravely limit reliability.
How can changes to the river banks and drainage be con-
What characteristics and qualities of things and
events are included and how they are recorded make
certain representations and analysis possible or
Should changes to water height be recorded as new attrib-
utes or should they replace the existing attributes?
Coordinate system
Commonly used for geographic information, maps
also make use of coordinate systems, a combination
of a projection, datum, and locational reference sys-
tem. The coordinate system is an especially impor-
tant choice for geographic information and in some
areas may even be legally defined.
What is the best coordinate system for showing the river
with sufficient accuracy and detail?
Will the map emphasize the areal extent of particular
attributes (vector) or the presence of particular attrib-
utes (raster)?
Recorded as vector data, the areal extent of each segment is
clear, but is the raster data perhaps more advantageous for
observing and measuring?
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