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| -rw-r--r-- | docs/source/operations/projections/lcc.rst | 51 |
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diff --git a/docs/source/operations/projections/lcc.rst b/docs/source/operations/projections/lcc.rst index 6db2a73c..3b2032d6 100644 --- a/docs/source/operations/projections/lcc.rst +++ b/docs/source/operations/projections/lcc.rst @@ -4,6 +4,39 @@ Lambert Conformal Conic ******************************************************************************** +A Lambert Conformal Conic projection (LCC) is a conic map projection +used for aeronautical charts, portions of the State Plane Coordinate +System, and many national and regional mapping systems. It is one of +seven projections introduced by Johann Heinrich Lambert in 1772. + +It has several different forms: with one and two standard parallels +(referred to as 1SP and 2SP in EPSG guidance notes). Additionally we +provide "2SP Michigan" form which is very similar to normal 2SP, but +with a scaling factor on the ellipsoid (given as `k_0` parameter). +It is implemented as per EPSG Guidance Note 7-2 (version 54, August +2018, page 25). It is used in a few systems in the EPSG database which +justifies adding this otherwise non-standard projection. + ++---------------------+----------------------------------------------------------+ +| **Classification** | Conformal conic | ++---------------------+----------------------------------------------------------+ +| **Available forms** | Forward and inverse, spherical and elliptical projection.| +| | One or two standard parallels (1SP and 2SP). | +| | "LCC 2SP Michigan" form can be used by setting | +| | `+k_0` parameter to specify elliposid scale. | ++---------------------+----------------------------------------------------------+ +| **Defined area** | Best for regions predominantly east–west in extent and | +| | located in the middle north or south latitudes. | ++---------------------+----------------------------------------------------------+ +| **Alias** | lcc | ++---------------------+----------------------------------------------------------+ +| **Domain** | 2D | ++---------------------+----------------------------------------------------------+ +| **Input type** | Geodetic coordinates | ++---------------------+----------------------------------------------------------+ +| **Output type** | Projected coordinates | ++---------------------+----------------------------------------------------------+ + .. figure:: ./images/lcc.png :width: 500 px :align: center @@ -31,3 +64,21 @@ Parameters .. include:: ../options/x_0.rst .. include:: ../options/y_0.rst + +.. option:: +k_0=<value> + + This parameter can represent two different values depending on the + form of the projection. In LCC 1SP it determines the scale factor + at natural origin. In LCC 2SP Michigan it determines the ellipsoid + scale factor. + + *Defaults to 1.0.* + +Further reading +############### + +#. `Wikipedia <https://en.wikipedia.org/wiki/Lambert_conformal_conic_projection>`_ +#. `Wolfram Mathworld <http://mathworld.wolfram.com/LambertConformalConicProjection.html>`_ +#. `John P. Snyder "Map projections: A working manual" (pp. 104-110) <https://pubs.er.usgs.gov/publication/pp1395>`_ +#. `ArcGIS documentation on "Lambert Conformal Conic" <http://desktop.arcgis.com/en/arcmap/10.3/guide-books/map-projections/lambert-conformal-conic.htm>`_ +#. `EPSG Guidance Note 7-2 (version 54, August 2018, page 25) <http://www.epsg.org/Guidancenotes.aspx>`_ |