Geography Reference
In-Depth Information
Review Questions
1. Identify the type (equal-angle, equal-area, compromise) of the fol-
lowing projections:
Mercator
Lambert
Mollweide
sinusoidal
azimuthal
Robinson
2. What is the difference between a secant and a tangent projection?
3. What is a transverse projection?
4. Why is a transverse Mercator projection better for north-south-
oriented areas and states (e.g., Illinois) than a Lambert conformal
conic projection?
5. What are the three important characteristics of projections?
6. Why is most GI projected to a two-dimensional, Cartesian coordi-
nate system?
7. Why should you never combine GI from different projections?
8. How can positional distortion be measured?
9. What is the difference between a geoid and a spheroid?
10. Why are Mercator and Peters projections technically satisfactory?
Why do people consider the Mercator projection to be a bad projec-
tion?
Answers
1. Identify the type (equal-angle, equal-area, compromise) of the fol-
lowing projections:
Mercator
Lambert
Mollweide
sinusoidal
azimuthal
Robinson
(Equal-shape)
(Equal-area) (Equal-area)
(Equal-area)
(Equal-distance) (Compromise)
2. What is the difference between a secant and a tangent projection?
A secant projection surface “touches” the earth's surface in two places; a
tangent projection “touches” only at one.
3. What is a transverse projection?
A transverse projection is a cylindrical projection, which is normally orien-
tated east-west, rotated 90 degrees to a north-south orientation.
4. Why is a transverse Mercator projection better for north-south-
oriented areas and states (e.g., Illinois) than a Lambert conformal
conic projection?
The conic projection works best for areas with an east-west orientation; its
line(s) of tangency run east-west. The transverse Mercator projection's line
of tangency runs north-south, providing a more accurate positional refer-
ence than the Lambert conformal conic projection of the same area.
5. What are the three important characteristics of projections?
Equal-shape: preservation of shapes; equal-area: preservation of areas;
equal-distance: preservation of distances
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