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Map Projections …is about presenting the
round Earth on a flat surface.Map Projections:
Vermeer’s Cartographer
What is a map projection?
• A projection is a way to make a flat representation of the Earth
The only accurate representation of the earth is a globe.
Only a globe preserves the map qualities of area, shape, direction, and distance.
Why are all map projections distorted?
• All map projections must distort size, shape, distance, or direction.
Watch the following video to find out why: http://goo.gl/oxC3v
Why do we use maps vs. globes?
-Practical -Technology is making maps less practical,
but their images will always be used.
Types of Map Projections
There are three main types of map projections A. Cylindrical/Mercator B. Conic C. Plane/Planar/Polar/Azimuthal
For Mercator projections, please know the following:
1. visual recognition 2. accuracy 3. Distortions 4. uses
Mercator/Cylindrical Projection
Visual Recogintion
At what angle to lines of latitude and longitude intersect on a cylindrical projection?
Accuracy / Distortions
Compare the size of landmasses on the cylindrical projection on the left with the Robinson projection on the right to answer the following questions.
Which landmasses appear much larger on the cylindrical projection than they actually are? Which landmasses on the cylindrical projection appear to be accurate in size?
Accuracy
What direction would you travel to get from ‘A’ to ‘B’? What direction would you travel to get from ‘C’ to ‘D’? True Compass Rose!
A
B
C D
Video of cylindrical/mercator projection
• http://goo.gl/AE5bR
For Conic projections, please know the following:
1. visual recognition 2. accuracy 3. uses
Conic Projection
Visual Recognition
Watch this: http://goo.gl/rJKp4 Answer these: What visual clue is covered that will help you
recognize a conic projection? (visual recognition) What parts of the world do conic projections show
accurately? (accuracy/uses) Distortions?
For Planar projections, please know the following:
1. visual recognition 2. Uses
Plane/���Planar/���Polar/���Azimuthal Projection
Visual Recognition
Accuracy
• Planar projections are accurate at the point the projection touches the map
Shape distorted at edge of projection.
Distortions:
Uses: ���Great Circle Routes • The line created when you cut the globe in
half connecting two points
• used by pilots because great circle routes appear as straight lines.
Uses:
Great Circle Route
This video shows planes travelling on great circle routes to Sydney, Australia
Optional http://goo.gl/lYnjw
For Gall-Peters projections, please know the following:
1. visual recognition 2. Why is considered politically correct?
Gall-Peters Projection Compare the Gall-Peters(left) to the cylindrical projection(right). 1. Both projections have latitude & longitude at right angles. What differences do you
see between the shape/size of landmasses.
2. Why is the Gall-Peters projection called the “politically correct” projection?
For Robinson projections, please know the following:
1. visual recognition
Robinson Projection
How do distortion levels of a Robinson Projection compare to distortion levels in other map projections?
For Interrupted projections
Ignore…..They are funky looking though!
Interrupted Projections:���visual recognition
Interrupted Projections
• We are used to looking at maps that are centered on the Prime Meridian.
VI. The Big Idea A. All map projections have distortions. B. Each projection has its own advantages and disadvantages
depending on the purpose of the map.
Summary Video Optional
http://goo.gl/TG8XM