Lecture on Map Projections

Introduction to Map Projections

• Converting a globe into a flat map involves cutting and stretching, leading to distortion.
• Fundamental problem: A sphere's surface cannot be represented on a plane without distortion.
• Since the 1500s, mathematicians have been developing algorithms for this conversion using projection.

Projection Methods

• Cylindrical Projection:
  • Imagine wrapping a cylinder around the globe.
  • The globe’s points are projected onto the cylinder, which is then unrolled into a rectangle.
• Other Projections:
  • Different projection techniques affect map appearance (shape, distance, direction, area).

Trade-offs of Map Projections

• Each projection involves compromises in shape, distance, direction, and land area.
• The utility of a projection depends on its intended use.

Mercator Projection

• Purpose and Use:
  • Maintains country shape.
  • Originally for navigation, preserving direction for easier oceanic navigation.
  • Utilizes a grid of right angles by varying latitude line distances.
• Issues:
  • Distortion of size, e.g., Africa appears similar in size to Greenland but is actually 14 times larger.
  • Criticized for fostering imperialist attitudes and ethnic bias.

Gall-Peters Projection

• Purpose: Equal area map with accurate land area representation.
• Issues: Distorts shapes significantly.

Impact of Satellites and GPS

• The 1960s saw satellites changing mapping purposes.
• GPS diminished the reliance on paper maps for navigation.
• Map projection choices now focus on aesthetics and presentation.

Continued Use of the Mercator Projection

• Still used in web mapping tools like Google Maps for its ability to preserve shape and angles.
• Preferred for close-up maps like cities.

Modern Cartography

• Rarely uses Mercator for world maps.
• Winkle Triple Projection adopted by National Geographic for balancing size and shape.
• No "right" projection; each serves different purposes.
• Encourages looking at a globe for a true view of Earth.

Additional Resources

• The True Size Of: An interactive tool for visualizing country size distortion.
• Acknowledgement to Mike Bostock for contributions to map projection studies.

Conclusion

• Projections involve compromises and there is no single perfect map.
• Choose projections based on specific needs and applications.