[PROJ] Parameter name discrepancy

[Even Rouault]

Jonathan,

Naming is always a trick subject.

Regarding Bonne,
- PROJ.4 lat_1 name come from Snyder's "Map Projections: a working manual" 
  (https://pubs.usgs.gov/pp/1395/report.pdf), which uses the term "standard parallel" (also a 
few times "central parallel"), and the phi_1 notation. See page 138-140
- The WKT2 parameter name comes from the EPSG dataset, which uses the "Latitude of 
natural origin" terminology.  See also EPSG Guidance Note 7-2
( https://drive.tiny.cloud/1/4m326iu12oa8re9cjiadxonharclteqb4mumfxj71zsttwkx/
62018e48-9da4-43e7-b598-1202cd96ec9f ), page 38, which uses phi0 / "latitude of the 
origin".
  Two different names, but that are mapped to the same maths. I'm not qualified to tell who is 
wrong / right


Regarding Loximuthal, I'm not sure where PROJ implementation comes from, but the maths 
do use lat_1. Regarding the WKT mapping, it is an artifact of GDAL WKT1 using 
"Latitude_of_origin" for the parameter name (no idea if that was appropriate), and thus the 
WKT2 equivalent has been mapped to "Latitude of natural origin" for consistency.

Even

> 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
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