Merge pull request #640 from busstoptaktik/lcca-add-mugnier-description

Add Clifford J. Mugnier notes about LCCA from PROJ.4 mailing list

1 files changed, 47 insertions, 2 deletions

diff --git a/src/PJ_lcca.c b/src/PJ_lcca.c
index 7d1355b9..cf1aa83f 100644
--- a/src/PJ_lcca.c
+++ b/src/PJ_lcca.c
@@ -1,5 +1,50 @@
-/* PROJ.4 Cartographic Projection System
-*/
+/*****************************************************************************
+
+               Lambert Conformal Conic Alternative
+               -----------------------------------
+
+    This is Gerald Evenden's 2003 implementation of an alternative
+    "almost" LCC, which has been in use historically, but which
+    should NOT be used for new projects - i.e: use this implementation
+    if you need interoperability with old data represented in this
+    projection, but not in any other case.
+
+    The code was originally discussed on the PROJ.4 mailing list in
+    a thread archived over at
+
+    http://lists.maptools.org/pipermail/proj/2003-March/000644.html
+
+    It was discussed again in the thread starting at
+
+    http://lists.maptools.org/pipermail/proj/2017-October/007828.html
+        and continuing at
+    http://lists.maptools.org/pipermail/proj/2017-November/007831.html
+
+    which prompted Clifford J. Mugnier to add these clarifying notes:
+
+    The French Army Truncated Cubic Lambert (partially conformal) Conic
+    projection is the Legal system for the projection in France between
+    the late 1800s and 1948 when the French Legislature changed the law
+    to recognize the fully conformal version.
+
+    It was (might still be in one or two North African prior French
+    Colonies) used in North Africa in Algeria, Tunisia, & Morocco, as
+    well as in Syria during the Levant.
+
+    Last time I have seen it used was about 30+ years ago in
+    Algeria when it was used to define Lease Block boundaries for
+    Petroleum Exploration & Production.
+
+    (signed)
+
+    Clifford J. Mugnier, c.p., c.m.s.
+    Chief of Geodesy
+    LSU Center for GeoInformatics
+    Dept. of Civil Engineering
+    LOUISIANA STATE UNIVERSITY
+
+*****************************************************************************/
+
 #define PJ_LIB__
 #include <errno.h>
 #include <proj.h>