Geography Reference
In-Depth Information
Exercises
1.
GPS and Navigation: Good for What?
What are the advantages of using GPS for navigation? What kinds of navigation ben-
efit the most? Why? What are some of the disadvantages? Are there potentials to
abuse GPS and collect personal information about people?
Finally, what about the use of GPS for surveying? Do you think any person
should be allowed to use GPS for surveying?
2.
EXTENDED EXERCISE:
Basic Surveying
Objective
Learn basic concepts of surveying, especially triangulation.
Overview
Most people don't think about it, but without surveyors, not much would happen in a
modern world. Houses, banks, roads, bridges, airports—all structures-rely on accu-
rate surveying. Property ownership is also surveyed, and when it's not done prop-
erly expensive legal conflicts are usually unavoidable. The mathematical foundation
of surveying is Euclidean geometry. This is the oldest geometry in the Western world
and the one that approximates very well our actual experience of distance relation-
ships.
In this exercise, you will learn a little about one of the oldest and most reliable
surveying techniques, the
plane table survey
, by preparing a simple survey and
doing some geometric evaluation. While the results of this exercise will not be accu-
rate, the technique you will learn, when conducted with the appropriate instruments
and robust procedures, will allow you to survey many things. And you will have a
new insight into why mathematics is important for maps.
Concepts
Many technologies are used in surveying. The plane table survey is an incredibly
simple technology for fairly accurate surveys. The technology usually uses a large
2
′×
2
′
board positioned over reference points. By using an accurate instrument for
sighting points (one type is called an “alidade”) and by keeping a consistent scale
for measuring distances, a surveyor measures angles that accurately bisect position
points. In other words, a traditional surveyor uses angles to determine distances and
rarely measures distances directly. (Using computer-based surveying devices
employing laser range finders, surveyors now are likely to measure distances.)
For this exercise, you will be using a simple piece of paper as a pseudo-plane
table working indoors (making it possible to do this exercise any time of year). In
comparison to working with a plane table, this diminishes the accuracy of the sur-
vey; however, the concepts and techniques remain the same. Using measurements
of angles, you will be applying Euclidean geometry's
law of sines
to construct a
locational survey of items in the classroom. Make sure to look at the law of sines
example before starting with the exercise.
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