[PROJ] Esri "local" projection

[Even Rouault]

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.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/proj/attachments/20230531/cfdcdaa0/attachment.htm>