<div><br></div>I completely forgot about the LCCA projection, discussed some years ago.<div>But, LCCA is not LCCA.<div>The discussion around the PJ_lcca.c code seems to refer to the Lambert Conic Near-Conformal projection, fully documented in the EPSG Guidance Note 7-2.</div><div>This projection is also fully documented in the Libproj4 manual from Gerald Evenden, as the Lambert Conformal Conic Alternative Projection.</div><div>The code from Libproj is used in PROJ. The libproj/proj algorithms are completely different from the EPSG algorithms.</div><div>Eitherway: indeed, do not use this code for regular LCC projections!</div><div> </div><div> Oscar van Vlijmen</div><div> </div><div> <br> </div><div>----Origineel Bericht----</div><div><blockquote style="margin-right: 0px; margin-left:15px;">Van : knudsen.thomas@gmail.com<br>Datum : 02/11/2017 22:55<br>Aan : proj@lists.maptools.org<br>Onderwerp : Re: [Proj] Grown error if re-projecting from 4269 to LCC (2285) and backward multiple times<br><br><div dir="ltr">
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Hi Dmitry,
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I googled around for the “alternative” Lambert, without luck, but then this afternoon, I accidentally misspelled Lambert as “Lamber”, and ran into this thread:
<a href="http://lists.maptools.org/pipermail/proj/2003-March/000644.html">http://lists.maptools.org/pipermail/proj/2003-March/000644.html</a> where PROJ.4 founder Gerald Evenden, and long time PROJ.4 maintainer Frank Warmerdam discusses the LCCA, and Gerald mentions that it is a truncated series, only introduced to be compatible with some legacy French/North African systems, that were defined using the truncated series.
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Gerald explicitly states that it should not be used for new work, so my recommendation of looking at it was terribly bad advice. Also, I had not realized that LCCA does not support the secant (“2 parallel”) case, and hence lat_0 and not lat_1 & lat_2 are used for parameterizing the projection.
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So enough about LCCA - it should not be used for anything but to maintain interoperability with legacy reference systems.
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