proj -le still enlists 'International 1909 (Hayford)' instead of 'International 1924'

[florisvdh]

Example of problem

$ dpkg -l | grep libproj
ii  libproj-dev:amd64                             7.2.1-1~focal0                          amd64        Cartographic projection library (development files)
ii  libproj19:amd64                               7.2.1-1~focal0                          amd64        Cartographic projection library

$ proj -le | grep -E '\sintl'
     intl a=6378388.0      rf=297.          International 1909 (Hayford)

$ projinfo -k ellipsoid -o proj,wkt_all EPSG:7022
PROJ string:
+ellps=intl

WKT2:2015 string:
ELLIPSOID["International 1924",6378388,297,
    LENGTHUNIT["metre",1],
    ID["EPSG",7022]]

WKT2:2019 string:
ELLIPSOID["International 1924",6378388,297,
    LENGTHUNIT["metre",1],
    ID["EPSG",7022]]

WKT1:GDAL string:
SPHEROID["International 1924",6378388,297,
    AUTHORITY["EPSG","7022"]]

Problem description

In the list of ellipsoids of proj -le, an older name is still used for the international ellipsoid. I'd expect it should be changed to 'International 1924' (EPSG:7022), cf. the output of projinfo. In both cases, reference is made to the PROJ name intl.

Maybe there are other such non-conforming cases in the output of proj -le, I think this should be checked.

Expected Output

$ proj -le | grep -E '\sintl'
     intl a=6378388.0      rf=297.          International 1924

Environment Information

• PROJ 7.2.1
• Linux Mint 20

Installation method

apt-get, with ubuntugis-unstable PPA

$ apt policy libproj19
libproj19:
  Installed: 7.2.1-1~focal0
  Candidate: 7.2.1-1~focal0
  Version table:
 *** 7.2.1-1~focal0 500
        500 http://ppa.launchpad.net/ubuntugis/ubuntugis-unstable/ubuntu focal/main amd64 Packages
        100 /var/lib/dpkg/status

[busstoptaktik]

@florisvdh yes - it would indeed make sense to change the proj -le designation:

The Hayford ellipsoid was based on investigations in 1909, published in 1910 as J.F. Hayford: Supplementary Investigation in 1909 of the Figure of the Earth and Isostasy, Coast and Geodetic Survey, 80pp. (freely accessible through Google Books).

In 1924 Hayford's ellipsoid was adopted by the IUGG as "the International Ellipsoid".

Hence either of

• Hayford, 1909 (for the year the work was done),
• Hayford, 1910 (for the year of publication), or
• International, 1924

would be reasonable names, but the "International, 1909" really is a peculiar mix of concepts.

[florisvdh]

Thank you for providing this interesting background @busstoptaktik! I understand the alternatives you enlist would all be equivalent. I think the advantage of changing to 'International 1924' would be syntactical consistency with EPSG:7022 and the WKT strings in which it is used, in order to avoid confusion.

[kbevers]

Ellipsoid names are defined here: https://github.com/OSGeo/PROJ/blob/master/src/ellps.cpp Feel free to open a pull request that fixes this.

[florisvdh]

The ellipsoid table in proj.db has:

auth_name	code	name	description
EPSG	7022	International 1924	NA

(NA meaning missing value; have generated this in R)

Not clear to me is if it is a goal to keep both data sources connected: ellps.cpp on the one hand and the 'PROJ' records of ellipsoid inside proj.db on the other hand. I think that further consistency would provide most clarity.

Here maybe the broader description International 1924 (Hayford 1909, 1910) could be added to the description field of ellipsoid (above). On the other hand, if name matching is desired, then perhaps one or the other should change names.

See #2537 for general issue on this.

[kbevers]

Not clear to me is if it is a goal to keep both data sources connected

@florisvdh ideally all ellipsoid information is read from the database, similar to proj_get_units_from_database() but at the moment we haven't got such a function. Someone just needs to step up and do it.