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
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