1 of 32

Map Projections

2 of 32

IT’S ALL A LIE! IT’S JUST A LIE!!

3 of 32

Map projection is the way we fit earth’s three-dimensional surface onto flat paper or a screen

It is impossible to accurately represent the spherical surface of the earth on a flat piece of paper. While a globe can represent the planet accurately, a globe large enough to display most features of the earth at a usable scale would be too large to be useful, so we use maps. Also imagine peeling an orange and pressing the orange peel flat on a table - the peel would crack and break as it was flattened because it can't easily transform from a sphere to a plane. The same is true for the surface of the earth and that's why we use map projections.

The term map projection can be thought of literally as a projection. If we were to place a light bulb inside a translucent globe and project the image onto a wall - we'd have a map projection. However, instead of projecting a light, cartographers use mathematical formulas to create projections.

Depending on the purpose of a map, the cartographer will attempt to eliminate distortion in one or several aspects of the map. Remember that not all aspects can be accurate so the map maker must choose which distortions are less important than the others. The map maker may also choose to allow a little distortion in all four of these aspects to produce the right type of map.

4 of 32

Facts to Know

3d to 2d- this is a challenge for map makers, distortion will take place
Map projection- think of a light bulb being set inside a translucent globe and it “projects” globe onto a flat wall, but cartographers use mathematical formulas to create maps
Map distortion- cartographers try to eliminate all distortions but impossible so they will focus on which distortions to minimize

It is impossible to accurately represent the spherical surface of the earth on a flat piece of paper. While a globe can represent the planet accurately, a globe large enough to display most features of the earth at a usable scale would be too large to be useful, so we use maps. Also imagine peeling an orange and pressing the orange peel flat on a table - the peel would crack and break as it was flattened because it can't easily transform from a sphere to a plane. The same is true for the surface of the earth and that's why we use map projections.

The term map projection can be thought of literally as a projection. If we were to place a light bulb inside a translucent globe and project the image onto a wall - we'd have a map projection. However, instead of projecting a light, cartographers use mathematical formulas to create projections.

Depending on the purpose of a map, the cartographer will attempt to eliminate distortion in one or several aspects of the map. Remember that not all aspects can be accurate so the map maker must choose which distortions are less important than the others. The map maker may also choose to allow a little distortion in all four of these aspects to produce the right type of map.

5 of 32

Three sources of map distortion

Map scale – most maps are smaller than the reality they represent. Map scales tell us how much smaller.
Map projection – this occurs because you must transform the curved surface of the earth on a flat plane.
Map type – you can display the same information on different types of maps.

6 of 32

HOW are maps distorted?

-Conformality Shapes appear more elongated or squat than in reality

-Distance Distance between two points may become increased or decreased

-Relative Size (Area/Equivalence) - the areas represented on the map are proportional to their area on the earth

Different areas may be altered so that one area may appear larger than another on a map but is in reality smaller

-Relative Direction Direction from one place to another can be distorted, angles of direction, rhumb line

7 of 32

Mercator Projection

8 of 32

Mercator Projection

Stretches the poles from one length to the size of the equator. The north-south scale is constant, but east-west scale increases to twice the north-south scale at 60 degrees N and infinitely at the poles.
Shapes are correct for all areas, and map has correct directional relationships.
Look at the size of Greenland and Antarctica.
Map exaggerates the distance between Chicago and Stockholm, both in northern latitudes.
Created in 1569

9 of 32

Africa is actually 14 larger than Greenland

10 of 32

Equal Area Projection

11 of 32

Compare the two.

12 of 32

13 of 32

Compare the two.

14 of 32

Equal Area Projection

Represents areas correctly, but distorts shapes.
If South America is 8 times larger than Greenland on the globe, it will be 8 times bigger on the map.

15 of 32

Robinson Projection

16 of 32

Robinson Projection

Frequently used
Distorts both size and shape, but not much
The major benefit of the Robinson projection is that oceans are uninterrupted. This projection is useful in depicting patterns of global interaction.
Considered a compromise projection

17 of 32

Goode’s Projection

18 of 32

interrupts the oceans and tucks Australia and New Zealand farther west than in reality
land masses appear relatively large compared to the oceans
minimized distortion in the shape of the various land masses and the size of one land mass compared to other land masses.

Goode’s Projection

19 of 32

Peter’s Projection

20 of 32

Compare the two!

21 of 32

Peter’s Projection

Controversial map
Not aesthetically pleasing
First introduced by historian and cartographer Dr. Arno Peters at a Press Conference in Germany in 1974
Almost represents land of equal area equally
Still distorts the shape because it is not a sphere��

22 of 32

Maps- “It’s freaking me out.”

.

23 of 32

30 of 32

Equal Area Projection

What is bad about this projection?

a. Shape

b. Size

c. Distance

direction

What is best about this projection?

a. Shape b. Size

c. Distance d. direction

31 of 32

The Mercator projection preserves

a. size b. area c. shape

d. scale e. distance

32 of 32

Goode’s Projection

What is bad about this projection?

Shape b. Size

c. Distance d. direction