Also called equidistant conic or conic, this projection can be based on one or two standard parallels. As the name implies, all circular parallels are an equal distance from each other, spaced evenly along the meridians. This is true whether one or two parallels are used.
Cone is tangential if only one standard parallel is specified and secant if two standard parallels are specified. Graticules are evenly spaced. The space between each meridian is equal, as is the space between each of the concentric arcs that describe the lines of latitude. The poles are represented as arcs rather than points.
If the pole is given as the single standard parallel, the cone becomes a plane and the resulting projection is the same as a polar azimuthal equidistant.
If two standard parallels are placed symmetrically north and south of the equator, the resulting projection is the same as equirectangular, and the equirectangular projection must be used. Use equirectangular if the standard parallel is the equator.
Lines of contact
Lines of contact depend on the number of standard parallels.
- Tangential projections (Type 1)—one line, indicated by the standard parallel.
- Secant projections (Type 2)—two lines, specified as first and second standard parallels.
Local shapes are true along the standard parallels. Distortion is constant along any given parallel. Distortion increases with distance from the standard parallels.
Distortion is constant along any given parallel. Distortion increases with distance from the standard parallels.
Locally true along the standard parallels.
True along the meridians and the standard parallels. Scale is constant along any given parallel but changes from parallel to parallel.
Range in latitude should be limited to 30°.
Uses and applications
Regional mapping of midlatitude areas that have a predominantly east–west extent.
Common for atlas maps of small countries.
Used by the former Soviet Union for mapping the entire country.
Number of standard parallels < 1 | 2 >
- Longitude of Central Meridian (DMS)
- Latitude of origin (DMS)
- Latitude of standard parallel (DMS)
- Longitude of the Central Meridian (DMS)
- Latitude of the 1st standard parallel (DMS)
- Latitude of the 2nd standard parallel (DMS)