Name Polyconic
GeoTIFF Code CT_Polyconic (22)
OGC WKT Name Polyconic
Supported By GeoTIFF, GXF, OGC WKT

Projection Parameters

Name EPSG # GeoTIFF ID OGC WKT Units Notes
Latitude of false origin 1 NatOriginLat latitude_of_origin Angular
Longitude of false origin 2 NatOriginLong central_meridian Angular
Scale factor at natural origin 5 ScaleAtNatOrigin (not included) Unitless
Easting of false origin 6 FalseEasting false_easting Linear
Northing of false origin 7 FalseNorthing false_northing Linear


In Geosoft GXF format it is known by the name "*Polyconic" indicating that it isn't an EPSG projection.

Discussions on the GeoTIFF mailing list a few years suggested that this projection should use ProjCenterLat and ProjCenterLong instead of NatOriginLat and NatOriginLong. Intergraph uses natural origin, and PCI uses ProjCenter as I believe does Erdas.

PROJ.4 Organization

  +proj=stere +lat_0=Latitude at natural origin 
              +lon_0=Longitude at natural origin
              +x_0=False Easting
              +y_0=False Northing