[PROJ] Parameter name discrepancy

[Jonathan Gale]

Hi PROJ list,



I've encountered a parameter discrepancy with a couple of ESRI CRS codes and I'm wondering if I've hit a bug. I'm using PROJ 6.2 and I get the following specifying Bonne via ESRI code:



projinfo ESRI:54024



PROJ.4 string:

+proj=bonne +lat_1=60 +lon_0=0 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs +type=crs



WKT2_2018 string:

PROJCRS["World_Bonne",

    BASEGEOGCRS["WGS 84",

        DATUM["World Geodetic System 1984",

            ELLIPSOID["WGS 84",6378137,298.257223563,

                LENGTHUNIT["metre",1]]],

        PRIMEM["Greenwich",0,

            ANGLEUNIT["Degree",0.0174532925199433]]],

    CONVERSION["World_Bonne",

        METHOD["Bonne",

            ID["EPSG",9827]],

        PARAMETER["Latitude of natural origin",60,

            ANGLEUNIT["Degree",0.0174532925199433],

            ID["EPSG",8801]],

        PARAMETER["Longitude of natural origin",0,

            ANGLEUNIT["Degree",0.0174532925199433],

            ID["EPSG",8802]],

        PARAMETER["False easting",0,

            LENGTHUNIT["metre",1],

            ID["EPSG",8806]],

        PARAMETER["False northing",0,

            LENGTHUNIT["metre",1],

            ID["EPSG",8807]]],

    CS[Cartesian,2],

        AXIS["(E)",east,

            ORDER[1],

            LENGTHUNIT["metre",1]],

        AXIS["(N)",north,

            ORDER[2],

            LENGTHUNIT["metre",1]],

    USAGE[

        SCOPE["unknown"],

        AREA["World"],

        BBOX[-90,-180,90,180]],

    ID["ESRI",54024]]



The WKT2 string refers to a "Latitude of natural origin" parameter, but the corresponding PROJ string uses "lat_1" which, according to the PROJ doc, is a required parameter that means "First standard parallel". My understanding of this projection leads me to believe that the PROJ string is using the correct parameter name and the WKT2 is not. I have seen the same discrepancy with the Loximuthal projected CRS specified by ESRI: 54023. Is this correct? Is this a bug?



Thanks,

Jonathan

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