Geography Reference
In-Depth Information
not help determine the extents of the towns. The concept fitness for use helps
get a grip on the slippery concept of quality. What this means is that we
need to know the intended purposes of a map before we decide what degree
of quality the map has for certain uses. You can read more about fitness for
use in Chapter 11.
For now let's let quality mean “fitness for use,” which is the ability of the
final product to support a particular task. Because of the endless number of
choices people face in cartography and geography, the quality of a map or
geographic information is related to the purpose, data sources, and data pro-
cessing. A highway map follows geographic representation and cartographic
representation choices that enhance its suitability for driving. While it is
obvious that a map showing all of the United States, Europe, or India is not
well suited for finding the nearest restaurant from an office, house, or hotel,
many maps and much geographic information are intended for multiple
uses, which will give them both strengths and weaknesses. Geographic infor-
mation may be collected and prepared for purposes that invite many differ-
ent uses, but it may in fact be ill-suited for particular purposes. In the end,
most maps are quite limited: a highway map is not very helpful for hikers (ex-
cept for helping them get to where they want to hike). Geographic informa-
tion can be handled more flexibly, but this does not remove significant lim-
its. Well-known errors have occurred when people creating road databases
included ferry routes as connections for national roads and then entered
them as roads in a car navigation system. More than one driver has taken a
surprise bath as a result.
Some of the many choices for map and geographic information quality
are fundamental. All are topics that this topic examines in depth. As you get
a better grip on these choices, you will better understand the quality of maps
and geographic information and also how to create better maps and geo-
graphic information. Below is a list of important topics and the chapters in
which they are covered.
Projections : How geographic locations on the round earth are shown on a flat
map or coordinate system is one of the biggest choices affecting quality
(Chapter 4).
Coordinate systems : Related to a projection, a coordinate system is especially
pertinent for geographic information, which can easily be combined
with other geographic information when it is in the same projection and
coordinate system (Chapter 5).
Symbols : How things and events are communicated is certainly one of the big-
gest choices affecting quality. For most people using maps, it is the most
important, because if people can't make sense out of the map, how can
anyone ever judge the quality (Chapter 10).
Geographic representation : Deciding how to show things and events is crucial
to whether a road can be modeled with different lanes of traffic and
sidewalks or only in terms of traffic flow.
Cartographic representation : If the geographic representation provides the
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