An azimuthal, conformal, polyconic (general) perspective projection. Used most conveniently with a single hemisphere. Illustrated centered on -90 degrees longitude and 0 degrees latitude.
This projection is provided under two names, as the Polar Stereographic form illustrated above for polar aspect and also as the Stereographic projection. These are two names for the same projection, which is often referred to in the literature using these two different names depending on whether it is used to show polar regions or to show other regions.
A specialized variant is known as the Universal Polar Stereographic Projection and is provided for use within the Universal Transverse Mercator system.
True only where the central latitude crosses the central meridian or, alternatively, along a circle concentric about the projection center (or a parallel on the polar aspect). Scale is constant along any circle having its center at the projection center, but scale increases moderately with distance from the center within a hemisphere.
Only the center or the circle of true scale (if not the center) is free from all distortion. Areas grow greater the farther from the center, albeit in a conformal manner.
Commonly used in the polar aspect for topographic maps of polar regions. The Equatorial aspect was used regularly for maps of the Eastern and Western hemispheres in the 17th and 18th centuries. Oblique aspects are used to show paths of solar eclipses.
Recommended for conformal mapping of regions approximately circular in extent.
Either the Polar Stereographic or the Stereographic projection must not be used to map the entire world’s surface at once: at least the point directly opposite to the projection origin must be excluded. This limitation arises because the Stereographic projections map the point opposite the projection origin to infinity, causing numeric overflows. For example, if the North Pole is used as the projection origin, the South Pole and region immediately about the South Pole should not be included in the map.
Apparently developed in polar aspect by Egyptians and Greeks by the 2nd Century BC
Specify the latitude origin and longitude origin to center the map projection to the area to be mapped. Specifying a non-Equatorial or non-polar origin causes an oblique projection.