[PROJ] confidence % in projinfo --identify

[Javier Jimenez Shaw]

Hi

I am a bit confused with "--identify" option in projinfo. I looked at the
documentation of the method "identify" of CRS classes in C++ trying to
understand.

Running
projinfo "$(projinfo ESRI:102654 -o WKT1:GDAL -q)" --identify -o WKT1:GDAL
Produces
PROJCS["NAD_1983_StatePlane_Colorado_Central_FIPS_0502_Feet (deprecated)",
....
Identification match count: 1
ESRI:102654: 100 %

so far so good.

Running (I just changed the wkt1 dialect in the inner call)
projinfo "$(projinfo ESRI:102654 -o WKT1:ESRI -q)" --identify -o WKT1:GDAL
Produces
PROJCS["NAD83 / Colorado Central (ftUS)",
....
Identification match count: 1
EPSG:2232: 100 %

Looking at the C++ documentation I think that a confidence of 100% means
that the names are the same (I do not really know which names it refers to.
Only the CRS name? geographic crs? datum? units? anything else? all?) But
in this case the input is "
NAD_1983_StatePlane_Colorado_Central_FIPS_0502_Feet" while the output is "NAD83
/ Colorado Central (ftUS)".
I know that both systems are equivalent (that is why ESRI:102654 is
deprecated), but I would not expect the 100% confidence having different
CRS names.

If I use this WKT string (the ESRI one, but adding the authority at the end
-I found it somewhere-)

PROJCS["NAD_1983_StatePlane_Colorado_Central_FIPS_0502_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",3000000.00031608],
  PARAMETER["False_Northing",999999.999996],
  PARAMETER["Central_Meridian",-105.5],
  PARAMETER["Standard_Parallel_1",38.45],
  PARAMETER["Standard_Parallel_2",39.75],
  PARAMETER["Latitude_Of_Origin",37.8333333333333],
  UNIT["US survey foot",0.304800609601219],
  AUTHORITY["ESRI","102654"]]

Produces
PROJCS["NAD83 / Colorado Central (ftUS)",
...
Identification match count: 1
ESRI:102654: 100 %

It is also changing the name to the one in EPSG, returning the ESRI code,
and with a confidence of 100%

Is all that intended? Maybe I misunderstood the meaning of the confidence
percentage.

Thanks.
.___ ._ ..._ .. . ._.  .___ .. __ . _. . __..  ... .... ._ .__
Entre dos pensamientos racionales
hay infinitos pensamientos irracionales.
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