Support LCC 2SP Michigan projection

1 files changed, 51 insertions, 0 deletions

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>`_