Add new Conversion "Local Orthographic"

[jjimenezshaw]

As mentioned in #4226, this "new" conversion (added in EPSG v11.015) is an extension of the Orthographic, extending proj=ortho with azimuth and scale.

Notice that the example in Guidance Note 7 part 2, section 3.6.6 uses the parameters of the CRS NAD83(2011) / San Francisco SFO B18. However the parameters are not exactly the same values as in the database for EPSG:10622.

• Closes prj with "local" projection from ArcGIS #4147
• Tests added
• Added clear title that can be used to generate release notes
• Fully documented, including updating docs/source/*.rst for new API

Fun fact: EPSG:10622 is aligned with the main runway (10L/28R) of San Francisco Airport, going (positive) straight to the east in that local system. The end of the runway is aprox. at coordinates (11740, 0) feet.

[jjimenezshaw]

When it is ok I can merge the commits in one.

[jjimenezshaw]

Outputs of EPSG:10622

PROJ_DATA=data bin/projinfo EPSG:10622 -o proj
PROJ.4 string:
+proj=ortho +lat_0=37.6289686531 +lon_0=-122.3939412704 +alpha=27.7928209333 
+k=0.9999968 +x_0=0 +y_0=0 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=us-ft +no_defs +type=crs

PROJ_DATA=data bin/projinfo EPSG:10622 -o wkt1_esri
WKT1:ESRI string:
PROJCS["NAD83_2011_San_Francisco_SFO-B18(ftUS)",GEOGCS["GCS_NAD_1983_2011",DATUM["D_NAD_1983_2011",
SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],
PROJECTION["Local"],PARAMETER["False_Easting",0.0],PARAMETER["False_Northing",0.0],
PARAMETER["Scale_Factor",0.9999968],PARAMETER["Azimuth",27.7928209333],
PARAMETER["Longitude_Of_Center",-122.3939412704],PARAMETER["Latitude_Of_Center",37.6289686531],
UNIT["US survey foot",0.304800609601219]]

PROJ_DATA=data bin/projinfo EPSG:10622 -o wkt1_gdal
WKT1:GDAL string:
PROJCS["NAD83(2011) / San Francisco SFO-B18 (ftUS)",
    GEOGCS["NAD83(2011)",
        DATUM["NAD83_National_Spatial_Reference_System_2011",
            SPHEROID["GRS 1980",6378137,298.257222101,
                AUTHORITY["EPSG","7019"]],
            AUTHORITY["EPSG","1116"]],
        PRIMEM["Greenwich",0,
            AUTHORITY["EPSG","8901"]],
        UNIT["degree",0.0174532925199433,
            AUTHORITY["EPSG","9122"]],
        AUTHORITY["EPSG","6318"]],
    PROJECTION["Local Orthographic"],
    PARAMETER["latitude_of_origin",37.6289686531],
    PARAMETER["central_meridian",-122.3939412704],
    PARAMETER["azimuth",27.7928209333],
    PARAMETER["scale_factor",0.9999968],
    PARAMETER["false_easting",0],
    PARAMETER["false_northing",0],
    UNIT["US survey foot",0.304800609601219,
        AUTHORITY["EPSG","9003"]],
    AXIS["Easting",EAST],
    AXIS["Northing",NORTH],
    AUTHORITY["EPSG","10622"]]

[jjimenezshaw]

With the code from master, without this changes, the WKT1_GDAL is like this:

PROJ_DATA=data bin/projinfo EPSG:10622 -o wkt1_gdal
WKT1:GDAL string:
PROJCS["NAD83(2011) / San Francisco SFO-B18 (ftUS)",
    GEOGCS["NAD83(2011)",
        DATUM["NAD83_National_Spatial_Reference_System_2011",
            SPHEROID["GRS 1980",6378137,298.257222101,
                AUTHORITY["EPSG","7019"]],
            AUTHORITY["EPSG","1116"]],
        PRIMEM["Greenwich",0,
            AUTHORITY["EPSG","8901"]],
        UNIT["degree",0.0174532925199433,
            AUTHORITY["EPSG","9122"]],
        AUTHORITY["EPSG","6318"]],
    PROJECTION["Local_Orthographic"],
    PARAMETER["Latitude of projection centre",37.6289686531],
    PARAMETER["Longitude of projection centre",-122.3939412704],
    PARAMETER["Azimuth at projection centre",27.7928209333],
    PARAMETER["Scale factor at projection centre",0.9999968],
    PARAMETER["Easting at projection centre",0],
    PARAMETER["Northing at projection centre",0],
    UNIT["US survey foot",0.304800609601219,
        AUTHORITY["EPSG","9003"]],
    AXIS["Easting",EAST],
    AXIS["Northing",NORTH],
    AUTHORITY["EPSG","10622"]]

Is the name of the projection PROJECTION["Local Orthographic"] correct with this PR? (see previous comment)

[rouault]

LGTM !
One point to check though is that projinfo "+proj=ortho +k_0=0.9 +type=crs" (or with +alpha != 0) instantiates a Local Orthographic projection and not a regular Orthographic.
You may need to fine tune PROJStringParser::Private::buildProjectedCRS() to add a special case, and a test for that in test_io.cpp

[rouault]

without this changes, the WKT1_GDAL is like this:

I believe we should rather fail. WKT1_GDAL is for what GDAL <= 2.4 and PROJ <= 5.x understood. Although it is not the end of the world if we generate that WKT1...

[jjimenezshaw]

instantiates a Local Orthographic projection and not a regular Orthographic.

Your are right. It is currently creating a METHOD["Orthographic", ID["EPSG",9840]],. Let me see how can I fine tune it.

[jjimenezshaw]

Doing the test in test_io.cpp, I noticed that the proj string is this

PROJ_DATA=data bin/projinfo EPSG:10622 -o proj
PROJ.4 string:
+proj=ortho +lat_0=37.6289686531 +lon_0=-122.3939412704 +alpha=27.7928209333 
+k=0.9999968 +x_0=0 +y_0=0 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=us-ft +no_defs +type=crs

using k instead of k_0.
What is the correct key to use there (as output)? if it is k_0, how can I force it?

The documentation I wrote is all with k_0, and the parameter works. Well, apparently both work in the input, but as output it is giving k.

[rouault]

What is the correct key to use there (as output)? if it is k_0, how can I force it?

This is due to

PROJ/src/iso19111/operation/parammappings.cpp

Line 311 in eec7351

common::UnitOfMeasure::Type::SCALE, k};

. I remember to have also wondered about k vs k_0 difference in the past and obviously can't remember the conclusion. Probably there isn't a clear one. Yes PROJ parser ( at least the one used to build PJ* object in src/init.cpp line 666) indifferently parses k and k_0, so that doesn't matter much ( in the context of PROJStringParser::Private::buildProjectedCRS() , you can use getParamValueK() to recognize both alternatives )