Geography Reference
In-Depth Information
Step 5: Calculate overall error
. Assuming a linear relationship between individual errors and
total error, use a root-mean-square equation and apply the law of error propagation to
determine the maximum potential error.
Step 6: Document the georeferencing process.
Documentation of the process and consid-
erations used in determining the georeferencing are important for people working with
the locality information later.
Based on: Wieczorek, J., Q. Guo, et al. (2004). The Point-Radius Method for Georeferencing Locality
Descriptions and Calculating Associated Uncertainty.
International Journal of Geographical Information
Science
,
18
(8), 745-767.
legally mandated coordinate system. Universal Transversal Mercator (UTM)
is widely used around the world, and thus is of great importance. All loca-
tion systems and coordinate systems use a scale to reduce the size of mea-
surements on the ground to map size or a comparable size in geographic
information. Geographic information from one scale can be easily converted
to another scale; it is much more labor-intensive to scale different maps.
Review Questions
1. What are common applications for spherical coordinate systems?
2. What is the main practical importance of coordinate systems?
3. What is the main difference between coordinate and locational sys-
tems?
4. What is the transformation from
x
,
y
to
x
,
y
called when all scale
factors are the same?
5. What is the difference between rectangular and polar coordinates?
6. For what purpose was Roman centuration devised?
7. What is the similarity between metes-and-bounds and the PLS in the
United States?
TABLE 5.3. Common U.S. Surveying Measurements
1 link = 0.66 feet or 7.92 inches
1 pole or 1 rod = 16.5 feet or 25 links
1 chain = 100 links, 4 rods, or 66 feet
80 chains = 1 mile, 320 rods, 1,760 yards, or 5,280 feet
1 acre = 10 sq. chains, 160 sq. rods, 4,840 sq. yards, or 43,560 sq. feet
1 square mile = 1 section of land or 640 acres
Township = 36 sq. miles (36 mile-sq. sections)
These survey measurements are historical and archaic, but because of their legal nature these
historical surveys are still valid. Current surveys generally use standard or metric measurements.
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