THE GEOGRAPHER’S TOOLS - Discovering Physical Geography - page 40

as the density of roads, location of human structures,
and vegetation type, to name but a few. These various
data sets are stored as individual layers that can be in-
dividually or collectively manipulated and analyzed. In

contrast to GIS, GPS stands for Global Positioning Sys-
tem and is the method through which precise locations
can be determined through triangulation with a constel-
lation of satellites.

C H E C K y O U R U N D E R S T A N D I N G

1. What are the two components of the geographic grid,
and how are they calculated?

7. What is the difference between active and passive
remote sensing?

2. Where are the low latitudes on Earth, and how do they
differ from the mid- and high latitudes?

8. Compare and contrast a Sun-synchronous orbit with a
geostationary orbit.

3. Discuss the concept of map projection and why it is nec-
essary when constructing maps.

9. What is a GPS satellite array, and how is it used to
determine location on Earth?

4. What kind of map projection would provide the most ac-
curate comparison of the shape of national boundaries
between countries in the low and high latitudes?

10. What are the three potential sources of error associated
with GPS?

11. Describe the character of a geographical information
system.

5. Which would have the larger scale: a map showing the
detail of New York City or a map showing the position of
New York City within the state of New York?

12. Compare and contrast three GIS data layers.

6. Define the concept of remote sensing.

ansWeRs to Visual ConCept CheCks

V I S U A L C O N C E P T C H E C K 2 . 1
a) Mont Blanc is located in the Alps in France.
b) Lake Chad is located in central Africa.
c) Valle de Luna (Valley of the Moon) is located in eastern Chile.

V I S U A L C O N C E P T C H E C K 2 . 2
a) The map on the left-hand side of the figure is a conformal projection, whereas the one on the right
is an equivalent projection. You can tell the difference because the conformal projection maintains
the shape of features on Earth but distorts their relative size, especially at the high latitudes. The
equivalent projection, in contrast, maintains relative shape, with size being distorted. To see the
difference between the two, note the relative shape and size of Greenland compared to that of
North America.

b) The map of the state of Washington has the relatively small scale, whereas the map of just the Seattle
area has the larger scale. You can tell the difference because the map of Washington shows a rela-
tively large geographic area that contains very little detail about Seattle. The map of Seattle, in con-
trast, shows much more detail about the city, including the road pattern and shape of water bodies.

V I S U A L C O N C E P T C H E C K 2 . 3
This infrared satellite image contains a variety of geographic information. The red, black, and bluish-gray
areas represent vegetation, water (mostly the Potomac River), and urban development, respectively.
Potential GIS layers include (1) the configuration of water bodies, (2) the distribution of vegetation,
(3) the road network, and (4) the pattern of urban development.