# Polyconic

Name | Polyconic
EPSG Code |
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 |

### Notes

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