This projection preserves the area of individual polygons while simultaneously maintaining a true sense of direction from the center. The general pattern of distortion is radial. This projection is best suited for individual landmasses that are symmetrically proportioned, either round or square.
Method of Projection:
Planar, projected onto a flat surface from any point on the globe. This projection can accommodate all aspects: equatorial, polar, and oblique.
Point of Tangency:
A single point, located anywhere, specified by longitude and latitude. This point is the arithmetic center when the projection is shown as a hemisphere.
Linear Graticules:
All aspects: The central meridian defining the point of tangency.
Equatorial aspect: The Equator.
Polar aspect: All meridians.
Properties:
Shape: Shape is minimally distorted, less that 2 percent, within 15 degrees from the focal point. Beyond that, angular distortion is more significant; small shapes are compressed radially from the center and elongated perpendicularly.
Area: Equal-area.
Direction: True direction radiating from the central point.
Distance: True at center. Scale decreases with distance from the center along radii and increases with increasing distance from the center perpendicular to the radii.
Limitations:
The data must be less than a hemisphere in extent. The software cannot process any area more than 90 degrees from the central point in any direction.
Uses and Applications:
Population density (Area).
Political boundaries (Area).
Oceanic mapping for energy, minerals, geology and tectonics (Direction).
This projection can handle large areas, thus it is used for displaying such geographical areas as entire continents and polar regions.
Equatorial aspect: Africa, Southeast Asia, Australia, Caribbean and Central America
Oblique aspect: North America, Europe and Asia
