MEPX
Chapter 6 of 10All chapters
  1. 1Reading a map
  2. 2Contours and terrain
  3. 3Grid references
  4. 4The compass
  5. 5Orienting and relocating
  6. 6Projections
  7. 7How satellite positioning works
  8. 8Where positioning fails
  9. 9Digital maps and routing
  10. 10Navigating in practice

Chapter 6 of 10

Projections

Why every flat map lies.

The unavoidable trade

A sphere cannot be flattened without distortion. A projection can preserve angles, or areas, or distances along certain lines, never all at once.

  • Mercator keeps angles, which is why it suited sea charts.
  • Equal area projections keep sizes honest but bend shapes.

Reading a map critically

Web maps use a Mercator variant, so Greenland appears the size of Africa while being about a fourteenth of it. The projection is a choice with consequences.