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Tyner indb
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Bog'liq Judith A. Tyner. Principles of map design. New York. „The Guilford Press”, 2010Representing scale
On a map, scale may be shown in any or all of these three ways. Topographic maps
and atlases frequently include all three forms of scale. Moreover, the graphic scale
may be shown in both English and metric units. However, on thematic maps and in
reports, periodicals, and newspapers, it is most common to use only a graphic scale.
Why? Because the cartographer isn’t always sure at what size the map will be repro-
duced—Will it be full-page, one column, or 1/2 page?—or even what size the page
will be. If the map is printed larger or smaller than its original size, the RF and verbal
scales will no longer be accurate. However, a graphic scale will enlarge or reduce in
the same proportion as the rest of the map. For maps that will be viewed on a moni-
tor, the only appropriate scale is a graphic scale. Monitors vary in size; therefore, the
map will be larger or smaller depending on the size of the screen.
A common mistake many novice mapmakers make is creating a graphic scale
that is more precise than the map (Figure 5.3). If a thematic map is very generalized
and at a small scale, such as 1:1,000,000, there is no advantage to making a bar scale
marked in 1-mile units. Measurements this small cannot be made from the map and
it gives an incorrect impression of the map’s accuracy. Even at a scale of 1:24,000 (1
inch represents 2,000 feet) a 20-foot-wide stream drawn to scale would be .01 inches
wide and would normally be drawn wider for legibility.
choosing scale
Several factors impact choosing a scale for a map: the subject and purpose of the map,
data resolution, map user needs, and the specified format.
If a map is designed for navigation or hiking or bicycling, it will need more detail
than if it is designed to show an overview of a water body, a national park, or a rec-
reation area. Bill Bryson in A Walk in the Woods expressed his frustration with maps
that were at too small a scale for the intended use:
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