Geoscience Reference
In-Depth Information
To check your answers and visualize locations on the opposite side of the globe, access
the Antipode Map, on http://www.antipodemap.com.
The phrase “dig to China” among Americans reflects the erroneous belief by some that if
you could dig a hole from your current position through the center of the Earth,
eventually you would emerge in China. Is this true? To visualize land masses on the
opposite side of the globe, visit “other side of the world” map on: http://www.
peakbagger.com/pbgeog/worldrev.aspx.
Why is it impossible for China to be on the opposite side of the world from
the USA? What is on the opposite side of the world from any point in the 48
contiguous United States? Is it a land mass or an ocean? Identify the land mass
or ocean that is at this location. You will find that on the opposite side of the
world from most of the continental United States is not China, but the Indian
Ocean. In which countries would a hole in a straight line emerge in China?
Most of Argentina and Chile would meet this criterion. What island country is
directly opposite to sections of Spain and Portugal? New Zealand meets this
criterion. Check early references on problems associated with the simultane-
ous global mapping of an infinite number of pairs of antipodal points (Tobler,
1961a; Arlinghaus and Nystuen, 1985).
In the next activity, you will test the concepts of accuracy and precision using
the GPS function in an ordinary smartphone. You will also have the oppor-
tunity to save your recorded path on your smartphone and map and analyze
your path in a web-based GIS.
1.6.2 Capturing points with a smartphone
On an iPhone or Android smartphone, enable the GPS or “location” func-
tion, and then access whatever default mapping tool you may have on the
smartphone. Go outside and plot your current position on the map with
your phone's default mapping tools. If possible, switch the base map to
a satellite image and zoom in as much as you can. Test your positional
accuracy in an open area versus in a wooded area or near a building. Can
you determine any differences in the horizontal accuracy? On most smart-
phones, the circle indicating your accuracy should become larger in areas
of heavy timber or buildings, indicating that the accuracy is degraded in
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