Lambert Conic Conformal (West Orientated)


Data source: EPSG

Information source: EPSG guidance note #7-2, http://www.epsg.org

Revision date: 2018-08-29


Note: These formulas have been transcribed from EPSG Guidance Note #7-2. Users are encouraged to use that document rather than the text which follows as reference because limitations in the transcription will be avoided.

In older mapping of Denmark and Greenland the Lambert Conic Conformal is used with axes positive north and west. To derive the projected Westing and Northing coordinates of a point with geographical coordinates (Lat, Lon) the formulas are as for the standard Lambert Conic Conformal (1SP) case (coordinate operation method code 9801) except for:

W =  FE – r.sin(theta)

In this formula the term FE retains its definition, i.e. in the Lambert Conic Conformal (West Orientated) method it increases the Westing value at the natural origin. In this method it is effectively false westing (FW).

The reverse formulas to derive the latitude and longitude of a point from its Westing and Northing values are as for the standard Lambert Conic Conformal (1SP) case except for:

theta' = atan2[(FE – W),{r0 – (N – FN)}]   (see implementation notes in GN7-2 preface for atan2 convention)
r' = +/-[(FE – W)^2 + {r0 – (N – FN)}^2]^0.5, taking the sign of n.


See Lambert Conic Conformal (1SP), code 9801, for general methodology.
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