[PROJ] ESRI deprecated CRS

[Nicolas Cadieux]

Hi,

While I am  not a CRS/proj wiz kid, a deprecated CRS  is outdated.  
Changes can be in the parameters or simple things like the name. 
Deprecated does not mean it's not good but likely not currently used by 
the state because of changes to the parameter. To my knowledge

102747 in proj.4 is

+proj=lcc +lat_1=36.76666666666667 +lat_2=37.96666666666667 +lat_0=36.33333333333334 +lon_0=-78.5 +x_0=3499999.999999999 +y_0=1000000 +datum=NAD83 +units=us-ft +no_defs

and 2284 in proj.4 is

+proj=lcc +lat_1=37.96666666666667 +lat_2=36.76666666666667 +lat_0=36.33333333333334 +lon_0=-78.5 +x_0=3500000.0001016 +y_0=999999.9998983998 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=us-ft +no_defs

According to https://epsg.io/102747 and https://epsg.io/2284.

As you can see, there are small differences like the reversal of the 
standard parallel 1 and 2. Others will give you more information.

Nicolas

On 2021-01-05 5:44 p.m., Javier Jimenez Shaw wrote:
> I found a CRS in proj.db that seems to be deprecated, but I do not 
> understand why exactly (or what does deprecated mean)
>
> NAD_1983_StatePlane_Virginia_South_FIPS_4502_Feet
>
> (I guess it happens to other CRSs as well. Let's focus in this one)
>
> in proj.db (table projected_crs) appears as ESRI:102747, deprecated
> I ended up in this repo, where I think we get the ESRI CRSs
> https://github.com/Esri/projection-engine-db-doc/blob/master/json/pe_list_projcs.json 
> <https://github.com/Esri/projection-engine-db-doc/blob/master/json/pe_list_projcs.json> 
> (json is easier to read than csv)
>
> That CRS appears twice in the file, with exactly the same name. The 
> only differences I can find are:
>  - wkid
>  - authority / version
>  - deprecated
>
>    { "wkid": 2284,
>      "latestWkid": 2284,
>      "macro": "PE_PCS_NAD_1983_VA_S_FT",
>      "name": "NAD_1983_StatePlane_Virginia_South_FIPS_4502_Feet",
>      "wkt": "PROJCS[\"NAD_1983_StatePlane_Virginia_South_FIPS_4502_Feet\",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[\"Lambert_Conformal_Conic\"],PARAMETER[\"False_Easting\",11482916.66666666],PARAMETER[\"False_Northing\",3280833.333333333],PARAMETER[\"Central_Meridian\",-78.5],PARAMETER[\"Standard_Parallel_1\",36.76666666666667],PARAMETER[\"Standard_Parallel_2\",37.96666666666667],PARAMETER[\"Latitude_Of_Origin\",36.33333333333334],UNIT[\"Foot_US\",0.3048006096012192]]",
>      "description": "NAD 1983 SPCS Virginia South (Feet)",
>      "authority": "EPSG",
>      "version": "5.3(9.0.0)",
>      "deprecated": "no",
>      "areaname": "USA - Virginia - SPCS - S",
>      "extent":
>      { "slat": 36.54,
>        "nlat": 38.28,
>        "llon": -83.68,
>        "rlon": -75.31
>      }
>    },
>    { "wkid": 102747,
>      "latestWkid": 2284,
>      "macro": "PE_PCS_NAD_1983_VA_S_FT",
>      "name": "NAD_1983_StatePlane_Virginia_South_FIPS_4502_Feet",
>      "wkt": "PROJCS[\"NAD_1983_StatePlane_Virginia_South_FIPS_4502_Feet\",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[\"Lambert_Conformal_Conic\"],PARAMETER[\"False_Easting\",11482916.66666666],PARAMETER[\"False_Northing\",3280833.333333333],PARAMETER[\"Central_Meridian\",-78.5],PARAMETER[\"Standard_Parallel_1\",36.76666666666667],PARAMETER[\"Standard_Parallel_2\",37.96666666666667],PARAMETER[\"Latitude_Of_Origin\",36.33333333333334],UNIT[\"Foot_US\",0.3048006096012192]]",
>      "description": "NAD 1983 SPCS Virginia South (Feet)",
>      "authority": "Esri",
>      "version": "8.0.1",
>      "deprecated": "yes",
>      "areaname": "USA - Virginia - SPCS - S",
>      "extent":
>      { "slat": 36.54,
>        "nlat": 38.28,
>        "llon": -83.68,
>        "rlon": -75.31
>      }
>    },
>
> I do not know what does it mean. Has ESRI deprecated its own CRS, but 
> includes the EPSG one (btw, which one?)... with exactly the same info 
> and name?
> The consequence is that it appears (only once) as deprecated in 
> proj.db. Is that intended?
>
> Making this query
> SELECT auth_name, code, name, deprecated FROM projected_crs WHERE name 
> LIKE "%Virginia%South%"
> I realized that the deprecated ones are duplicated in a similar way in 
> ESRI file. The non deprecated ones (from CORS96) are not "duplicated" 
> in the ESRI file. Is there any reason behind that?
>
> A more general question: What does mean that a CRS is deprecated?
>
> Thanks
> .___ ._ ..._ .. . ._. .___ .. __ . _. . __..  ... .... ._ .__
> Entre dos pensamientos racionales
> hay infinitos pensamientos irracionales.
>
>
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-- 
Nicolas Cadieux
https://gitlab.com/njacadieux

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