map projections - coach grigg ap human geography /...

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?

Brainstorm advantages that maps have over

globes and write them below.

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’?

Does direction appear to be accurate on a Mercator Projection?

A

B

C D

Uses

Watch the following video to see a common

use of cylindrical/mercator projections

http://goo.gl/obRzv

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)

What is distorted, size or shape? (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

http://goo.gl/lYnjw

Compromise Projections

With out using the internet or book, what do

you think a compromise projection is?

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, please

know the following:

1. visual recognition

Interrupted Projections:

visual recognition

Interrupted Projections

Interrupted Projections

Why might you want to use this projection?

• 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

http://goo.gl/TG8XM