Tuesday, January 26, 2021

How Well Do You Know Mercator?

The Mercator Map Projection has some very well known problems. Invented in 1569 by Flemish cartographer Gerardus Mercator the map is very useful for navigating - particularly at sea. A straight line on a Mercator projection map is a line of constant true bearing, which makes it very easy for navigators to plot straight-line courses. Unfortunately because the linear scale of a Mercator projection map gets bigger with latitude geographical areas get distorted as you move away from the equator. For example on a Mercator map Greenland and Africa appear to be the same size even though Africa is in fact much larger than Greenland.

You probably already knew that. In fact I'm guessing you are already an expert on the problems of creating two dimensional maps of a three dimensional world. Which is why you should excel at completing the BBC's Mind-Blowing Map Quiz. In this quiz you are asked to answer six different questions - some of them directly related to the distortions caused by the Mercator Projection. 

If you get less than 6 out of 6 in the BBC quiz then you need to study the Mercator Map Projection a little more ...

The Organization of Cartographers for Social Equality believe that the Mercator map projection "has fostered European Imperialist attitudes for centuries and created an ethnic bias against the third world". However they do admit that the Mercator projection is a useful tool for European sailors.

If you want a more balanced account of the Mercator projection then you you should read Tass's excellent introduction to the Flemish Cartographer Gerardus Mercator and his popular map projection. Mercator - It's a Flat, Flat World provides a wonderfully illustrated history of the Mercator projection and its creator, while also examining the benefits and problems of this popular cartographic representation of the world.

Tass's analysis of the Mercator projection includes an annotated guide to Gerardus Mercator's groundbreaking 1569 map, the 'New and More Complete Representation of The Terrestrial Globe Properly Adapted for Use in Navigation'. This guided tour introduces you to the map and provides a close-up examination of some of the map's features. The tour explains why the map is so useful as an aide to navigating at sea. It also explores the extent and limitations of geographical knowledge in the period when the map was made.

Alongside this detailed tour of Mercator's 1569 map 'Mercator - It's a Flat, Flat World' explores why it is so difficult to create an accurate flat two dimensional map of a three dimensional world. It explores the advantages and disadvantages of some of the other map popular projections and it illustrates how the different map projections each distort different areas of the world.

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