Notes on Map Projections

Introduction

• Converting a globe into a flat map involves cutting and stretching the globe.
• Represents the dilemma of mapmakers: a sphere cannot be represented as a plane without distortion.

Projection

• Definition: The process of translating a globe into a flat surface.
• Cylindrical Projection: Popular method using a theoretical cylinder over the globe, projecting points from the sphere onto the cylinder's surface.
  • Unrolling the cylinder results in a rectangular map.
• Different objects can be used for projection, affecting the final appearance of the map.

Trade-offs of Projections

• Each projection has trade-offs in:
  • Shape
  • Distance
  • Direction
  • Land area
• Some projections can be misleading or helpful based on their intended use.

Mercator Projection

• Description: A widely taught map in schools and used by Google Maps.
• Strengths:
  • Preserves country shapes.
  • Useful for navigation (preserves direction).
• Purpose: Designed for navigation so that lines drawn on the map maintain accurate compass angles.
• Limitations:
  • Distorts land area (e.g., Greenland vs. Africa).
  • Enlarges objects closer to the poles.
• Critique:
  • Promotes imperialistic attitudes and ethnic bias against the third world.

Gall-Peters Projection

• Description: Equal area map that accurately represents land area.
• Comparison:
  • More accurate size comparison of Greenland and Africa compared to Mercator.
  • Shapes of countries are distorted.

Changes in Mapping Post-1960s

• Introduction of satellites providing precise location and navigation data.
• Shift from paper maps to digital navigation (GPS).
• Impact:
  • Cartographers moved away from the Mercator projection as a navigation tool due to its misleading nature.

Modern Mapping Practices

• Most web mapping tools (e.g., Google Maps) still use Mercator for close-up accuracy.
  • Preserves angles and shapes for smaller scale maps.
• Many cartographers now prefer non-rectangular projections for a balance between size and shape accuracy.
  • Example: Winkle Triple Projection adopted by National Geographic Society in 1998.

Conclusion

• No single "right" projection exists; many projections serve different tasks.
• Best representation of Earth: a globe.
• For exploring map distortions, visit thetruesizeof.com.
• Acknowledgment to Mike Bostock for contributions to the subject.