Topographic Maps _ Landforms

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					                                Topographic Maps & Landforms

Historically, the development of highly accurate, detailed topographic maps has largely been
driven by military requirements. A unique characteristic that distinguishes topographical maps
from other kinds of maps is the fact that they show the topography, or shape of the land, in
addition to other features such as roads, rivers, lakes, etc. Because topographical maps show
the shape of the land, they are the most suitable type of map for most outdoor activities that
take place in areas that are not heavily populated. Hence, in order to study landscape
features, a topographic map is best. The key to using topographic maps is to understand the
structure and function of contour lines. Each contour line connects places that have the same
elevation or height.

Space-based remote sensing of the Earth used to be the sole domain of the U.S.
government. Imagery of our planet taken by intelligence satellites was highly classified, and
relatively few people had access to the imagery. That began to change in the mid 1980’s and
early 1990’s when other countries began launching very capable Earth-imaging satellites and
making that imagery available for sale. To stay competitive, the U.S. government opened the
door for American companies to build and launch even better commercial imaging satellites,
building on the heritage of three decades of work by the intelligence community. GeoEye-1,
an advanced commercial, high-resolution, color Earth-imaging satellite, was launched in
2008. From an orbit 423 miles in space, GeoEye-1 can discern an object on the ground the
size of home plate on a baseball field and can map an object that size to within 16 feet of its
true location on the surface of the Earth. However, the U.S. government currently restricts
public distribution of GeoEye-1 images to commercial markets to half-meter ground
resolution. Anyone can see the GeoEye-1 imagery on Google Earth or Google Maps.

From receding ice caps on Mt. Kilimanjaro to the "secret" nuclear facilities of other nations,
satellite imagery can help people understand human impact on the planet by providing
timely, quality location intelligence. Even in the entertainment industry, video games like
"High Altitude Warfare Experimental" and hit movies like "Transformers", "The Bourne
Ultimatum", and "Green Zone" use satellite imagery to provide realism and authenticity to the
visuals that support the story line.
Landforms can be weathered and changed. Both types of maps would show these changes in
elevation, shape, and other physical changes. Topographic maps can reflect changes caused
by volcanic explosions, like Mt. St. Helen or other natural disasters that change the surface of
the Earth. Satellite maps can show the impact of wildfires, mudslides, tsunamis, etc. The
change in the amount of material in a river delta caused by flooding or by drought conditions
can be documented.

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