86 THe geOgRaPHiC anD
CaRTOgRaPHiC FRaMeWORK
shown individually and they are close together, they may be grouped. Many maps
created with GIS programs show great detail, but if the map is reduced for printing,
the individual features coalesce into a “blob” and would be better grouped at the
outset.
This is also the case when there are too many categories of a larger group to be
shown, such as vegetation categories. Forty vegetation
categories on a large-scale
map might be useful to the researcher, but in an atlas they can be grouped into fewer
broad categories (Figure 5.7).
Classification
We commonly classify or categorize data for many noncartographic purposes. A
teacher will group a series of numerical exam scores into categories to assign grades;
censuses group age categories and the like. Data for cartographic purposes are also
categorized to make them more meaningful and to clarify or emphasize patterns of
distribution. Just as a list of numerical scores in random order must be manipulated
to make it meaningful, numbers spread over a map must be manipulated to make a
significant display. Normally, this aspect of generalization applies to thematic data
and is especially important when symbolizing volumes. The classification of data is
discussed in more detail in Chapter 8.
exaggeration
Earlier, the example of a road, a railroad, and a river in a narrow valley was put forth.
If the scale of the map does not permit all three features to be shown without overlap,
the valley can be widened or exaggerated to accommodate the features (Figure 5.8).
Displacement
When a road and a railroad parallel one another, they are frequently displaced, that
is, moved farther apart so that the two lines can be distinguished (Figure 5.8). In the
Wind Farms
Wind Farms
fIgURe 5.7.
Data may be grouped into categories.
scale, Compilation, and generalization 87
narrow valley example, the valley width may be exaggerated and the road, railroad,
and river displaced.
symbolization
Symbolization includes the selection and design of symbols to represent geographic
phenomena on a map. Not all cartographers agree that symbolization is a part of
generalization. Because assigning symbols to various
phenomena is central to the
cartographic process, some consider symbolization to be completely separate. In this
book, symbolization, because of the size of the subject, is treated separately in Chap-
ters 7 and 8.
