Map Types & Projections: Notes Why do we use maps? – Many can be stored at once – Easier (than a...
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Map Types & Projections: Notes Why do we use maps? – Many can be stored at once – Easier (than a globe) to carry – Can have special purposes – Scales allow
Map Types & Projections: Notes Why do we use maps? Many can
be stored at once Easier (than a globe) to carry Can have special
purposes Scales allow different levels of detail What are the
limitations of maps? Globe is 3D, maps are 2D. 2D will lead to
distortion for shapes, distances, sizes, and directions VS. What do
you think?
Slide 2
Different Types of Maps Different types of maps try to protect
from different distortions Conformal Conformal The shapes of places
are accurate. Distance Distance Measured distances are accurate.
Area/Equivalence Area/Equivalence The areas represented on the map
are proportional to their area on the earth. Direction Direction
Angles of direction are portrayed accurately.
Slide 3
Maps from Different Shapes Planar Planar Good: polar maps,
minimal distortion at the center, show directions & distance
well Bad: edges have distorted area, shape; only shows half of the
world at once Cylindrical Cylindrical Good: navigation, show
direction and distance well, showing the whole world Bad: distort
shape & area near the poles (check out Greenland &
Antarctica) Conic Conic (a compromise) Good: mid-latitude maps like
the US and Europe, showing a smaller area Bad: adds distortion of
all aspects, but attempts to keep each at a minimum
Slide 4
Planar Map
Slide 5
Cylindrical Map
Slide 6
USA: Cylindrical Map
Slide 7
Conic Map
Slide 8
USA: Conic Map
Slide 9
USA: Conic & Cylindrical
Slide 10
Draw the Map Types On your note-sheets, draw the map types to
the best of your ability.
Slide 11
Describe if the following are Planar, Cylindrical, or
Conic
Slide 12
Interrupted Projection These types of maps try to depict the
continents as accurately as possible by leaving blank space in the
less important areas of the map.
Slide 13
Common Map Projections types projections Even the same types of
maps can become different projections (or representations)
How do these map projections differ? Azimuthal Equal-Area
Mercator Azimuthal Equidistant Robinson Changes a sphere to a disk
-Shows the size of areas correctly -Does not represent angles
correctly Standard map for nautical purposes b/c easy to plot a
course across an ocean. -Shows shape of areas correctly -Accurate
near the equator but becomes distorted along the poles (distorts
these areas) Map for showing airline distances -Attempts to show
distances, & direction accurately -Useful for polar projections
but distorts area & shapes the fuller you get from the center
point. Projection used to show the whole world at once (the
compromise map) -Tries to reduce all types of distortion in size,
shape, direction, & distance. -Distortion at the poles
Slide 17
Projections: Discussion Questions So, what map projections
should we use most often? So, what map projections should we use
most often? How do map projections affect our perception of the
world? How do map projections affect our perception of the
world?
The Controversy Over Projection Types The Controversy Over
Projection Types Whats an accurate map?Mercator Cons: Centers the
world on Europe Inflates the northern areas at the expense of the
equatorial regions Pros: Easy to travel across an ocean: represents
lines of constant course Peters Cons: Created for political
purposes, not cartography (lacks data) Distorts the shape of
continents Pros: Peters: "the Mercator projection overvalues the
white man and distorts the picture of the world to the advantage of
the colonial masters of the time What can you conclude from this
comparison? Summarize each projection in your own words.
Slide 21
How big is Greenland? How big is Greenland? On this Mercator
projection Greenland and South America appear similar in size. The
inset map shows that South America is actually about 15 times
larger than Greenland.
Slide 22
How big is Africa? Greenland appears to be the same size as
Africa, yet the land mass of Africa is actually 14 times larger:
How big is Europe? And compare Europe vs. South America (3.8
million square miles vs. 6.9 million square miles):
Slide 23
The Mercator map distorts the relative size of the north and
the south. The south is actually more than twice as large (38.6
million square miles to 18.9 million square miles) Why were
cartographic decisions made this way?
Slide 24
Where are the majority of third world nations located?
Slide 25
Why does the Northern hemisphere HAVE to be at the top of the
map? Could we change the world by changing our map?
Slide 26
Special Purpose Maps Also called thematic maps they cover one
theme in a region Train lines, postal codes, population density,
precipitation, elevation, etc.
Slide 27
Special Purpose Maps: Types Choropleth: different colors are
used to show different values Choropleth Isarithmic/contour: have
lines that connect regions with similar values & themes
Isarithmic/contour Dot: each dot represents a certain number of
some occurrence or feature Dot Proportional symbol: varying sizes
of a symbol represent the real difference in some occurrence or
feature Proportional symbol
Slide 28
Choropleth Isarithmic/contour Dot Proportional Symbol
Slide 29
A Special Purpose Example: Topography A map with lines and
symbols representing the natural and man-made features of a part of
the earths surface. They show the location and shapes of mountains,
valleys, plains, etc. Why would this be a useful map for hikers, or
engineers?
Slide 30
Maps: Reflection Describe two (2) ways that a special purpose
map could be used to represent something from the state of
Connecticut. Describe two (2) ways that a special purpose map could
be used to represent something from the state of Connecticut.
