def test_mercator_a_operation__defaults():
aeaop = MercatorAConversion()
assert aeaop.name == "unknown"
assert aeaop.method_name == "Mercator (variant A)"
assert _to_dict(aeaop) == {
"Latitude of natural origin": 0.0,
"Longitude of natural origin": 0.0,
"False easting": 0.0,
"False northing": 0.0,
"Scale factor at natural origin": 1.0,
}
def test_mercator_a_operation():
aeaop = MercatorAConversion(
latitude_natural_origin=1,
longitude_natural_origin=2,
false_easting=3,
false_northing=4,
scale_factor_natural_origin=0.5,
)
assert aeaop.name == "unknown"
assert aeaop.method_name == "Mercator (variant A)"
assert _to_dict(aeaop) == {
"Latitude of natural origin": 1.0,
"Longitude of natural origin": 2.0,
"False easting": 3.0,
"False northing": 4.0,
"Scale factor at natural origin": 0.5,
}
def _mercator(cf_params):
"""
http://cfconventions.org/cf-conventions/cf-conventions.html#_mercator
"""
if "scale_factor_at_projection_origin" in cf_params:
return MercatorAConversion(
latitude_natural_origin=cf_params.get("standard_parallel", 0.0),
longitude_natural_origin=cf_params.get(
"longitude_of_projection_origin", 0.0
),
false_easting=cf_params.get("false_easting", 0.0),
false_northing=cf_params.get("false_northing", 0.0),
scale_factor_natural_origin=cf_params["scale_factor_at_projection_origin"],
)
return MercatorBConversion(
latitude_first_parallel=cf_params.get("standard_parallel", 0.0),
longitude_natural_origin=cf_params.get("longitude_of_projection_origin", 0.0),
false_easting=cf_params.get("false_easting", 0.0),
false_northing=cf_params.get("false_northing", 0.0),
)
def test_mercator_a():
crs = ProjectedCRS(conversion=MercatorAConversion(1, 2, 3, 4))
expected_cf = {
"semi_major_axis": 6378137.0,
"semi_minor_axis": crs.ellipsoid.semi_minor_metre,
"inverse_flattening": crs.ellipsoid.inverse_flattening,
"reference_ellipsoid_name": "WGS 84",
"longitude_of_prime_meridian": 0.0,
"prime_meridian_name": "Greenwich",
"horizontal_datum_name": "World Geodetic System 1984",
"grid_mapping_name": "mercator",
"standard_parallel": 1.0,
"longitude_of_projection_origin": 2.0,
"false_easting": 3.0,
"false_northing": 4.0,
"scale_factor_at_projection_origin": 1.0,
}
cf_dict = crs.to_cf()
assert cf_dict.pop("crs_wkt").startswith("PROJCRS[")
assert cf_dict == expected_cf
# test roundtrip
_test_roundtrip(expected_cf, "PROJCRS[")