[PROJ] Incorrect WKT strings for ESRI defined CRSs?

[Luí­s Moreira de Sousa]

Dear all,

my apologies in advance if I am missing something and bothering you for naught. I noticed some strange results with the Homolosine projection using the WKIDs from ESRI:

$ cat wgs.md
-15 15
175 0
170 35
160 55
-140 50
$ cs2cs +init=epsg:4326 +to ESRI:54052 wgs.md
-1612895.57 1669792.36 0.00
19480910.89 0.00 0.00
15501890.04 3896182.18 0.00
11323880.61 6049814.33 0.00
-10648864.61 5536706.32 0.00

These results do not match those obtained with an explicit formulation of this CRS:

$ cs2cs +init=epsg:4326 +to +proj=igh +lat_0=0 +lon_0=0 +datum=WGS84 +units=m +no_defs wgs.md
-1499101.98 1669792.36 0.00
19480910.89 0.00 0.00
16105847.11 3896182.18 0.00
12540237.72 6049791.84 0.00
-14174481.82 5536683.82 0.00

The differences are all with easting coordinates, making me suspect that something was amiss with lobe definitions. Therefore I went checking in the database:

spatialite> SELECT text_definition FROM projected_crs WHERE code=54052;
PROJCS["World_Goode_Homolosine_Land",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Goode_Homolosine"],PARAMETER["False_Easting",0.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian", 0.0],PARAMETER["Option",1.0],UNIT["Meter",1.0]]

The "Goode_Homolosine" projection name refers to this class:
https://github.com/OSGeo/PROJ/blob/46c47e9adf6376ae06afabe5d24a0016a05ced82/src/projections/goode.cpp

It defines no lobes and does not correspond to any of the projections proposed by Goode. I believe this CRS WKT should instead refer to the actual Homolosine for land masses, identifiable with the long name "Interrupted Goode Homolosine" and the short id "igh":
https://github.com/OSGeo/PROJ/blob/f3561e5749fefd957f67cc631378d1c39161a310/docs/source/operations/projections/igh.rst

Also inquiring the database, one can note the Oceanic version also referring to the rogue lobe-less projection:

spatialite> SELECT text_definition FROM projected_crs WHERE code=54053;
PROJCS["World_Goode_Homolosine_Ocean",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",637137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Goode_Homolosine"],PARAMETER["False_Easting",0.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian" ,-160.0],PARAMETER["Option",2.0],UNIT["Meter",1.0]]

In this case the right projection should possibly be the one named "Oceanic view":
https://github.com/OSGeo/PROJ/blob/2e5470387df8c713af18e601c0e6a4b352294556/docs/source/operations/projections/igh_o.rst

I hope this makes sense. Thank you.

--
Luís
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/proj/attachments/20200624/68c0d61c/attachment-0001.html>