[PROJ] Esri "local" projection

[Even Rouault]

Le 31/05/2023 à 01:24, Javier Jimenez Shaw a écrit :
> Thanks Even for the quick response.
>
> Can I create a CRS as WKT with the ob_tran?

in a PROJ-specific way, yes:

$ bin/projinfo "+proj=ob_tran +o_proj=moll +o_lon_p=40 +o_lat_p=50 
+lon_0=60 +type=crs"
PROJ.4 string:
+proj=ob_tran +o_proj=moll +o_lon_p=40 +o_lat_p=50 +lon_0=60 +type=crs

WKT2:2019 string:
PROJCRS["unknown",
     BASEGEOGCRS["unknown",
         DATUM["World Geodetic System 1984",
             ELLIPSOID["WGS 84",6378137,298.257223563,
                 LENGTHUNIT["metre",1]],
             ID["EPSG",6326]],
         PRIMEM["Greenwich",0,
             ANGLEUNIT["degree",0.0174532925199433],
             ID["EPSG",8901]]],
     CONVERSION["unknown",
         METHOD["PROJ ob_tran o_proj=moll"],
         PARAMETER["o_lon_p",40,
             ANGLEUNIT["degree",0.0174532925199433,
                 ID["EPSG",9122]]],
         PARAMETER["o_lat_p",50,
             ANGLEUNIT["degree",0.0174532925199433,
                 ID["EPSG",9122]]],
         PARAMETER["lon_0",60,
             ANGLEUNIT["degree",0.0174532925199433,
                 ID["EPSG",9122]]]],
     CS[Cartesian,2],
         AXIS["(E)",east,
             ORDER[1],
             LENGTHUNIT["metre",1,
                 ID["EPSG",9001]]],
         AXIS["(N)",north,
             ORDER[2],
             LENGTHUNIT["metre",1,
                 ID["EPSG",9001]]],
     REMARK["PROJ CRS string: +proj=ob_tran +o_proj=moll +o_lon_p=40 
+o_lat_p=50 +lon_0=60"]]

>
>
> On Wed, 31 May 2023, 00:43 Even Rouault, <even.rouault at spatialys.com> 
> wrote:
>
>     Javier,
>
>     I suspect you might be able to apply the azimuth by using the
>     infamous +proj=ob_tran.  The tricky part will be to find on which
>     parameter(s) of ob_tran (o_lat_p, o_lon_p, lon_0) to map it.
>
>     Possibly relevant, there's at least 2 different code
>     implementations attempting at reproducing the Spilhaus from Esri,
>     which include a azimuth parameter:
>
>     - cf https://github.com/OSGeo/PROJ/issues/1851#issuecomment-943138537
>
>     - or
>     https://github.com/neocarto/bertin/blob/main/src/projections/spilhaus.js
>     + https://github.com/d3/d3-geo/blob/main/src/rotation.js
>
>     The maths ressemble those of proj=ob_tran
>
>     Even
>
>     Le 31/05/2023 à 00:24, Javier Jimenez Shaw a écrit :
>>     Hi
>>
>>     Some use cases of Esri "local" projection are arriving to my
>>     desk. This projection works in Esri software, but not in PROJ
>>     (obviously also not in QGIS)
>>
>>     One example is this WKT1_ESRI
>>
>>     PROJCS["Hycroft001",GEOGCS["GCS_North_American_1983",DATUM["D_North_American_1983",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Local"],PARAMETER["False_Easting",13264.924],PARAMETER["False_Northing",46473.418],PARAMETER["Scale_Factor",1.00025],PARAMETER["Azimuth",15.786],PARAMETER["Longitude_Of_Center",-116.7048269],PARAMETER["Latitude_Of_Center",42.88212865],UNIT["Foot_US",0.3048006096012192]]
>>
>>     Looking at their documentation, it seems to be this one:
>>     https://desktop.arcgis.com/en/arcmap/latest/map/projections/local.htm
>>
>>     The biggest difference I see with the Orthographic from PROJ is
>>     the Azimut parameter. I have the impression that the azimut is
>>     just a rotation of the axes, but it is not clear to me in the
>>     Snyder book (page 145. If you do not have it, it is available at
>>     https://pubs.er.usgs.gov/publication/pp1395 )
>>
>>     Is there are alternative in PROJ?
>>     Does it make sense to add this transformation?
>>
>>     Thanks
>>     Javier
>>     .___ ._ ..._ .. . ._.  .___ .. __ . _. . __..  ... .... ._ .__
>>
>>     _______________________________________________
>>     PROJ mailing list
>>     PROJ at lists.osgeo.org
>>     https://lists.osgeo.org/mailman/listinfo/proj
>
>     -- 
>     http://www.spatialys.com
>     My software is free, but my time generally not.
>
-- 
http://www.spatialys.com
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