Geography Reference
In-Depth Information
Global tessellation.
From
www.spatial-effects.com
. Reprinted by permission
of Geoff Dutton.
Representative fraction
•
Scale bar
•
Statement
•
The three types are equivalents, but have different representations. A
representative fraction
provides a ratio between the same units of measure on
a page and on the ground. A
scale bar
graphically represents distinct dis-
tances at the scale of the geographic information or map. A
statement
describes the scale in words. The most important thing for representing
scale is that the measurement units on the page (or for the geographic infor-
mation) and on the ground must be kept the same. For example, the repre-
sentative fraction scale 1:24,000 indicates that 1 inch on the map corre-
sponds to 24,000 inches on the ground. Divide by 12 (the number of inches
in a foot) and you'll have the basis for the statement of scale: “1 inch equals
2,000 feet.” Using metric units, the calculations are even easier: the represen-
tative fraction scale 1:25,000 indicates that 1 cm on the map corresponds to
Representative scale and scale bars from a USGS map.
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