What is a map projection?

A way of showing the curved surface of the earth

on a flat map.

Why are there so many different types of maps?

Each map has strengths and weaknesses.

What causes each map’s strengths and weaknesses?

One cannot take a 3 dimensional object and make it 2 dimensional

without

Distortion

Planar Projections

Planar/Azimuthal A planar projection is also called an

azimuhtal projection. It distorts size and shape. Azimuthal projection shows the earth

centered in such a way that a straight line coming from the center to any other point represents the shortest distance. These are often used in air navigation.

Conical Projections

ConicalA conic projection comes from

the idea of placing a cone over part of the globe. This projection shows shape

fairly accurately, but it distorts landmasses at the edges of the map.

Cylindrical/Mercator

Mercator/Cylindrical A mercator projection comes from the idea

of wrapping a piece of paper around a globe to make a cylinder. Such a map shows shapes fairly accurately but not size or distance. Areas away from the equator are distorted.

Greenland and Alaska will appear much larger than they are on a globe. These are primarily used for sea travel.

Robinson

Robinson A Robinson projection is

commonly used in textbooks. It shows the entire earth with nearly the true sizes and shapes of the continents and oceans. The shapes of the landforms near

the poles appear flat.

Gall-Peters

Gall-Peters

On the Gall-Peters projection, the sizes of landmasses are accurate. In particular South America, Africa and Southeast Asia are shown in their correct size relationship to North America and Europe. Their shapes, however, are greatly distorted

and distances are inaccurate.

The important thing to remember…….All maps have

strengths and weaknesses.

All Have Distortion!!

Heavyweight Champion Robinson

vs.

Contender Gall-Peters

http://www.youtube.com/watch?v=n8zBC2dvERM