Looking at the World: Map Projections

When mapmakers create maps, they have to present the round Earth on a flat surface -- this creates some distortions. For example, some maps do not show the true size of land masses, but they might show true directions and true shapes.

Other maps show size in true proportion, but distort shapes. Mapmakers have to choose the kind of projection that is best for their purposes.

In this presentation you will see a few map projections, but not all of them by any means. This will give you a basic idea about some of the main types of projections.

Cylindrical Projection (write down the underlined info) This is like wrapping a piece of paper around the Earth. Pretend the continents and oceans have ink on them, so when the paper comes off, there is a map. Mercator map = cylindrical

NOT this one

Cylindrical Map: Mercator. Draw a rectangle with the grid pattern to show that’s what a cylindrical map looks like.

Mercator Map Look at the Mercator cylindrical map again. Guess how many United States could fit in Africa based on this map.

Mercator Map

Cylindrical Map Projection. Write down the underlined information This projection is useful for showing the entire earth in a simple rectangular format.

Hobo-Dyer Equal Area Cylindrical Projection Map North was placed at the top of the map because European navigators used the North star and the magnetic compass Before that the top of the map was East

Hobo-Dyer Equal-Area Cylindrical Projection Map Who says North has to be “up”? Other maps exist showing South as “up”, and these maps are perfectly legitimate Several Australians made what we call “upside down” maps

Hobo-Dyer Equal Area Cylindrical Projection Map

Conic Projections: Write underlined info These maps are designed as if a cone had been placed over the globe -- almost like a dunce cap placed over the earth.

This one

Conic Projection Map. Sketch map below so you know what a conic projection looks like.

Conic Projections: write underlined info Conic projections are most often used to show mid-latitude areas in the northern and southern hemisphere. A “standard parallel” is chosen near the center of the area to be mapped. Near this standard parallel, distortion of geometric characteristics is small.

Conic Projections. Write underlined info Away from the standard parallel, the shapes are distorted, and the areas are not equal to the reality on the Earth.

Conic Projection Map Mid-latitude – little distortion distortion

Flat Plane Projection Map. Write underlined info Flat plane projection maps are maps that appear to touch the globe at one spot, like putting a flat piece of paper on the North Pole.

Sketch what the flat plane projection looks like so you will remember it.

Flat Plane Projection Maps

Flat Plane Projection Maps. Write down underlined info. This type of projection is useful for mapping large regions and showing airline distances from the center point.

Flat Plane Projection Map. Write down underlined info. The area is accurate and the distortion of shapes is relatively low near the center point.

Flat Plane Projection Map. Write down underlined info. Distances and directions are correct ONLY from the center point of the projection. Distances are correct between points along a straight line through the center. All other distances incorrect. Distortions of areas and shapes increases away from the center point.

A Look at Different Projections

Types of Map Distortions: Maps Can “Lie”. Write down underlined info. Shape: Things may appear longer or chunkier than they really are Distance: The distance between two points may become increased or decreased Relative Size: One area might look larger than another on a map, but in reality it might be smaller Direction: Direction from one place to another might be distorted

Uninterrupted Projections Two Examples: Robinson Mercator

Robinson Map

Advantage of Robinson Map: Displays information across the oceans Disadvantage of the Robinson Map: By giving space to oceans, the land areas are much smaller than on interrupted maps the same size

Mercator Map

Advantages of Mercator Map: Little shape distortion Direction is consistent Rectangular map Disadvantages of Mercator Map: Area is really distorted toward the poles – it makes high-latitude places look bigger than they really are

The Peter’s Projection Map. Write down name of map and info below. This is the most accurate area map

Look at the Peter’s Projection Map again (it distorts shapes, but shows the right sizes). About how many United States could fit into Africa based on this map?