def _inspect_data(self):
"""
Extract coordinate reference system and min/max values from a
GDAL supported raster data file.
"""
if self._data is None:
# TODO: This method is really ugly, but is nice for testing
self._data = {}
df = gdal.Open(self.filename)
# TODO: df may be None?
crs = df.GetProjection()
if crs:
spref = SpatialReference(wkt=crs)
# default to epsg:4326
auth = spref.GetAuthorityName(None) or 'epsg'
code = spref.GetAuthorityCode(None) or '4326'
self._data['crs'] = "%s:%s" % (auth.lower(), code)
# LOG.info('Detected CRS: %s', self._data['crs'])
else:
self._data['crs'] = 'epsg:4326' # use epsg:4326 as default
band = df.GetRasterBand(1)
self._data['min'], self._data['max'], _, _ = band.GetStatistics(
True, False)
self._data['nodata'] = band.GetNoDataValue()
self._data['datatype'] = band.DataType
def get_identifier(crs):
"""
Given a CRS, generate a unique idenfier for it. Eg: "EPSG:2193"
"""
if isinstance(crs, str):
crs = SpatialReference(crs)
if isinstance(crs, SpatialReference):
auth_name = crs.GetAuthorityName(None)
auth_code = crs.GetAuthorityCode(None)
return f"{auth_name}:{auth_code}"
raise RuntimeError(f"Unrecognised CRS: {crs}")
def test_parse():
assert crs_util.parse_name(TEST_WKT) == "WGS 84"
assert crs_util.parse_authority(TEST_WKT) == ("EPSG", "4326")
assert crs_util.parse_name(AXIS_LAST_WKT) == "WGS 84"
assert crs_util.parse_authority(AXIS_LAST_WKT) == ("EPSG", "4326")
# Strangely this doesn't entirely work using osgeo:
spatial_ref = SpatialReference(TEST_WKT)
assert spatial_ref.GetName() == "WGS 84"
assert spatial_ref.GetAuthorityName(None) is None
assert spatial_ref.GetAuthorityCode(None) is None
def wkt_to_gpkg_spatial_ref_sys(wkt):
"""Given a WKT crs definition, generate a gpkg_spatial_ref_sys meta item."""
spatial_ref = SpatialReference(wkt)
organization = spatial_ref.GetAuthorityName(None) or "NONE"
srs_id = crs_util.get_identifier_int(spatial_ref)
return [{
"srs_name": spatial_ref.GetName(),
"definition": wkt,
"organization": organization,
"srs_id": srs_id,
"organization_coordsys_id": srs_id,
"description": None,
}]
def wkt_to_gpkg_spatial_ref_sys(wkt):
"""Given a WKT crs definition, generate a gpkg_spatial_ref_sys meta item."""
# TODO: Better support for custom WKT. https://github.com/koordinates/sno/issues/148
spatial_ref = SpatialReference(wkt)
spatial_ref.AutoIdentifyEPSG()
organization = spatial_ref.GetAuthorityName(None) or "NONE"
srs_id = spatial_ref.GetAuthorityCode(None) or 0
return [{
"srs_name": spatial_ref.GetName(),
"definition": wkt,
"organization": organization,
"srs_id": srs_id,
"organization_coordsys_id": srs_id,
"description": None,
}]
def get_identifier_str(crs):
"""
Given a CRS, generate a stable, unique identifier for it of type 'str'. Eg: "EPSG:2193"
"""
if isinstance(crs, str):
crs = SpatialReference(crs)
if not isinstance(crs, SpatialReference):
raise RuntimeError(f"Unrecognised CRS: {crs}")
auth_name = crs.GetAuthorityName(None)
auth_code = crs.GetAuthorityCode(None)
if auth_name and auth_code:
return f"{auth_name}:{auth_code}"
code = auth_name or auth_code
if code and code.strip() not in ("0", "EPSG"):
return code
return f"CUSTOM:{get_identifier_int(crs)}"
def generate_postgis_spatial_ref_sys(cls, v2_obj):
"""
Generates the contents of the spatial_ref_sys table from the v2 object.
The result is a list containing a dict per table row.
Each dict has the format {column-name: value}.
"""
result = []
for crs_name, definition in v2_obj.crs_definitions().items():
spatial_ref = SpatialReference(definition)
auth_name = spatial_ref.GetAuthorityName(None) or "NONE"
crs_id = crs_util.get_identifier_int(spatial_ref)
result.append({
"srid": crs_id,
"auth_name": auth_name,
"auth_srid": crs_id,
"srtext": definition,
"proj4text": spatial_ref.ExportToProj4(),
})
return result
