The latitudinally equal-differential polyconic projection (
等差分纬线多圆锥投影) is a
polyconic map projection
In cartography, a map projection is any of a broad set of Transformation (function) , transformations employed to represent the curved two-dimensional Surface (mathematics), surface of a globe on a Plane (mathematics), plane. In a map projection, ...
in use since 1963 in mainland
China
China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...
. Maps on this projection are produced by China's State Bureau of Surveying and Mapping and other publishers. Its original method of construction has not been preserved, but a mathematical approximation has been published.
[
]
Description
As a polyconic projection, the parallels are
arcs of circles that are not concentric. The points of no distortion are on the central meridian at 44°N/S latitude. Meridians are convex away from the straight central meridian, and parallels are gently concave away from the equator. The projection is neither
equal-area nor
conformal; rather, it is a compromise projection.
Maps on this projection do not show the north pole, instead cropping the high latitudes along a straight line whose latitude varies but that never reaches the pole. By convention, the projection is centered at 150° such that the Pacific Ocean dominates the center-right of the map and China is placed about 45° west of the central meridian, in a location favorable for low distortion. Greenland is split at the left and right edges of the map, and the northern edge of the map clips the highest regions of the island.
See also
*
List of map projections
This is a summary of map projections that have articles of their own on Wikipedia or that are otherwise WP:NOTABLE, notable. Because there is no limit to the number of possible map projections,
there can be no comprehensive list.
Table of proj ...
*
Winkel tripel projection
The Winkel tripel projection (Winkel III), a modified azimuthal map projection of the world map, world, is one of Winkel projection, three projections proposed by German cartographer Oswald Winkel (7 January 1874 – 18 July 1953) in 1921. The p ...
, which has similar characteristics.
References
External links
Archive of Chinese world map on the latitudinally equal-differential polyconic projection
Map projections
{{cartography-stub