[PROJ] Esri "local" projection

[Javier Jimenez Shaw]

Thanks Even for the quick response.

Can I create a CRS as WKT with the ob_tran?


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
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