Equal-area map

"Area-preserving maps" redirects here. For the mathematical concept, see Measure-preserving dynamical system.

The equal-area Mollweide projection

In map projection, equal-area maps preserve area measure, generally distorting shapes in order to do that. Equal-area maps are also called equivalent or authalic. An equal-area map projection cannot be conformal, nor can a conformal map projection be equal-area.

Several equivalent projections were developed in an attempt to minimize the distortion of countries and continents of planet Earth, keeping the area constant. Equivalent projections are widely used for thematic maps showing scenario distribution such as population, farmland distribution, forested areas, etc.

Applications

Equal Earth projection, an equal-area map.

Equal area representation implies that a region of interest in a particular portion of the map will share the same proportion of area as in any other part of the map.

Statistical grid

The term "statistical grid" refers to a discrete grid (global or local) of an equal-area surface representation, used for data visualization, geocode and statistical spatial analysis.

List of equal-area projections

These are some projections that preserve area:

• Albers conic
• Pseudoconical equal-area
  • Bonne
  • Bottomley
  • Werner
• Cylindrical equal-area
  • Lambert cylindrical equal-area (0°)
  • Behrmann projection (30°)
  • Hobo–Dyer (37°30′)
  • Gall–Peters projection (45°)
• Pseudocylindrical equal-area
  • Collignon
  • Eckert II, IV and VI
  • Equal Earth
  • Goode's homolosine
  • Mollweide
  • Sinusoidal
  • Tobler hyperelliptical
• McBryde-Thomas Flat-Polar Quartic Projection
• Hammer
• Lambert azimuthal equal-area
• Strebe 1995
• Snyder's equal-area polyhedral projection, used for geodesic grids.

See also

• Equiareal map (mathematics)
• Measure-preserving dynamical system
• Geodesic polygon area