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