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Enhanced OGC reader #2191

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Jul 24, 2023
Merged

Enhanced OGC reader #2191

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125 changes: 95 additions & 30 deletions lib/cartopy/io/ogc_clients.py
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@
import collections
import io
import math
from urllib.parse import urlparse
import warnings
import weakref
from xml.etree import ElementTree
Expand Down Expand Up @@ -412,7 +413,12 @@ def find_projection(match_projection):
matrix_sets = self.wmts.tilematrixsets
tile_matrix_set = matrix_sets[tile_matrix_set_name]
crs_urn = tile_matrix_set.crs
tms_crs = _URN_TO_CRS.get(crs_urn)
tms_crs = None
if crs_urn in _URN_TO_CRS:
tms_crs = _URN_TO_CRS.get(crs_urn)
elif ':EPSG:' in crs_urn:
epsg_num = crs_urn.split(':')[-1]
tms_crs = ccrs.epsg(int(epsg_num))
if tms_crs == match_projection:
result = tile_matrix_set_name
break
Expand All @@ -422,6 +428,7 @@ def find_projection(match_projection):
matrix_set_name = find_projection(target_projection)
if matrix_set_name is None:
# Search instead for a set in _any_ projection we can use.
# Nothing to do for EPSG
for possible_projection in _URN_TO_CRS.values():
# Look for supported projections (in a preferred order).
matrix_set_name = find_projection(possible_projection)
Expand All @@ -445,8 +452,15 @@ def validate_projection(self, projection):

def fetch_raster(self, projection, extent, target_resolution):
matrix_set_name = self._matrix_set_name(projection)
wmts_projection = _URN_TO_CRS[
self.wmts.tilematrixsets[matrix_set_name].crs]
crs_urn = self.wmts.tilematrixsets[matrix_set_name].crs
if crs_urn in _URN_TO_CRS:
wmts_projection = _URN_TO_CRS[crs_urn]
elif ':EPSG:' in crs_urn:
epsg_num = crs_urn.split(':')[-1]
wmts_projection = ccrs.epsg(int(epsg_num))
else:
raise ValueError(f'Unknown coordinate reference system string:'
f' {crs_urn}')

if wmts_projection == projection:
wmts_extents = [extent]
Expand Down Expand Up @@ -574,7 +588,25 @@ def _wmts_images(self, wmts, layer, matrix_set_name, extent,
# Find which tile matrix has the appropriate resolution.
tile_matrix_set = wmts.tilematrixsets[matrix_set_name]
tile_matrices = tile_matrix_set.tilematrix.values()
meters_per_unit = METERS_PER_UNIT[tile_matrix_set.crs]
if tile_matrix_set.crs in METERS_PER_UNIT:
meters_per_unit = METERS_PER_UNIT[tile_matrix_set.crs]
elif ':EPSG:' in tile_matrix_set.crs:
epsg_num = tile_matrix_set.crs.split(':')[-1]
tms_crs = ccrs.epsg(int(epsg_num))
# catch UserWarning from .to_dict(), because the resulting
# dictionary does not contain all information for all projections;
# need only 'units' here
with warnings.catch_warnings():
warnings.simplefilter("ignore")
Comment on lines +599 to +600
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What is the warning we are ignoring? We should at least mention why this is here with a comment.

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Yes, this is a UserWarning from .to_dict() from proj because the dict does not give all details of each projection. But we only check for the units here.
I added a comment.

crs_dict = tms_crs.to_dict()
crs_units = crs_dict.get('units', '')
if crs_units != 'm':
raise ValueError('Only unit "m" implemented for'
' EPSG projections.')
meters_per_unit = 1
else:
raise ValueError(f'Unknown coordinate reference system string:'
f' {tile_matrix_set.crs}')
tile_matrix = self._choose_matrix(tile_matrices, meters_per_unit,
max_pixel_span)

Expand Down Expand Up @@ -666,7 +698,15 @@ def __init__(self, service, features, getfeature_extra_kwargs=None):
raise ImportError(_OWSLIB_REQUIRED)

if isinstance(service, str):
# host name such as mapserver.gis.umn.edu or
# agroenvgeo.data.inra.fr from full address
# http://mapserver.gis.umn.edu/mapserver
# or https://agroenvgeo.data.inra.fr:443/geoserver/wfs
self.url = urlparse(service).hostname
# WebFeatureService of owslib
service = WebFeatureService(service)
else:
self.url = ''

if isinstance(features, str):
features = [features]
Expand Down Expand Up @@ -703,14 +743,22 @@ def default_projection(self):
else:
default_urn = default_urn.pop()

if str(default_urn) not in _URN_TO_CRS:
if (str(default_urn) not in _URN_TO_CRS) and (
":EPSG:" not in str(default_urn)
):
raise ValueError(
f'Unknown mapping from SRS/CRS_URN {default_urn!r} to '
'cartopy projection.')

f"Unknown mapping from SRS/CRS_URN {default_urn!r} to "
"cartopy projection.")
self._default_urn = default_urn

return _URN_TO_CRS[str(self._default_urn)]
if str(self._default_urn) in _URN_TO_CRS:
return _URN_TO_CRS[str(self._default_urn)]
elif ':EPSG:' in str(self._default_urn):
epsg_num = str(self._default_urn).split(':')[-1]
return ccrs.epsg(int(epsg_num))
else:
raise ValueError(f'Unknown coordinate reference system:'
f' {str(self._default_urn)}')

def fetch_geometries(self, projection, extent):
"""
Expand Down Expand Up @@ -757,12 +805,20 @@ def fetch_geometries(self, projection, extent):
geom_proj = _URN_TO_CRS[srs]
if geom_proj != projection:
raise ValueError(
'The geometries are not in expected projection. '
f'The geometries are not in expected projection. '
f'Expected {projection!r}, got {geom_proj!r}.')
elif ':EPSG:' in srs:
epsg_num = srs.split(':')[-1]
geom_proj = ccrs.epsg(int(epsg_num))
if geom_proj != projection:
raise ValueError(
f'The EPSG geometries are not in expected '
f' projection. Expected {projection!r}, '
f' got {geom_proj!r}.')
else:
warnings.warn(
'Unable to verify matching projections due to '
'incomplete mappings from SRS identifiers to cartopy '
f'Unable to verify matching projections due to '
f'incomplete mappings from SRS identifiers to cartopy '
f'projections. The geometries have an SRS of {srs!r}.')
return geoms

Expand All @@ -788,24 +844,33 @@ def _to_shapely_geoms(self, response):
points_data = []
tree = ElementTree.parse(response)

for node in tree.findall(f'.//{_MAP_SERVER_NS}msGeometry'):
# Find LinearRing geometries in our msGeometry node.
find_str = f'.//{_GML_NS}LinearRing'
if self._node_has_child(node, find_str):
data = self._find_polygon_coords(node, find_str)
linear_rings_data.extend(data)

# Find LineString geometries in our msGeometry node.
find_str = f'.//{_GML_NS}LineString'
if self._node_has_child(node, find_str):
data = self._find_polygon_coords(node, find_str)
linestrings_data.extend(data)

# Find Point geometries in our msGeometry node.
find_str = f'.//{_GML_NS}Point'
if self._node_has_child(node, find_str):
data = self._find_polygon_coords(node, find_str)
points_data.extend(data)
# Get geometries from http://mapserver.gis.umn.edu/mapserver
# and other servers
for node in tree.iter():
snode = str(node)
if ((_MAP_SERVER_NS in snode) or
(self.url and (self.url in snode)
)):
s1 = snode.split()[1]
tag = s1[s1.find('}') + 1:-1]
if ('geom' in tag) or ('Geom' in tag):
# Find LinearRing geometries in our msGeometry node.
find_str = f'.//{_GML_NS}LinearRing'
if self._node_has_child(node, find_str):
data = self._find_polygon_coords(node, find_str)
linear_rings_data.extend(data)

# Find LineString geometries in our msGeometry node.
find_str = f'.//{_GML_NS}LineString'
if self._node_has_child(node, find_str):
data = self._find_polygon_coords(node, find_str)
linestrings_data.extend(data)

# Find Point geometries in our msGeometry node.
find_str = f'.//{_GML_NS}Point'
if self._node_has_child(node, find_str):
data = self._find_polygon_coords(node, find_str)
points_data.extend(data)

geoms_by_srs = {}
for srs, x, y in linear_rings_data:
Expand Down
Binary file added lib/cartopy/tests/mpl/baseline_images/mpl/test_features/wfs_france.png
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14 changes: 14 additions & 0 deletions lib/cartopy/tests/mpl/test_features.py
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Original file line number Diff line number Diff line change
Expand Up @@ -70,3 +70,17 @@ def test_wfs():
edgecolor='red')
ax.add_feature(feature)
return ax.figure


@pytest.mark.network
@pytest.mark.skipif(not _OWSLIB_AVAILABLE, reason='OWSLib is unavailable.')
@pytest.mark.xfail(raises=ParseError,
reason="Bad XML returned from the URL")
@pytest.mark.mpl_image_compare(filename='wfs_france.png')
def test_wfs_france():
ax = plt.axes(projection=ccrs.epsg(2154))
url = 'https://agroenvgeo.data.inra.fr:443/geoserver/wfs'
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I'm wondering if it would be beneficial for us to start mocking servers rather than relying on external sources? Basically, if it'd be reasonable to add both the XML you download from there and the image to the repository and then make a Mock response from that url. Then we wouldn't need these network marks anymore.

This doesn't have to be undertaken here, it is more me just wondering how reliable these external servers are and if there is a way around hitting them constantly if they don't like that.

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We could use vcrpy to record and playback http traffic. That would be a low-cost way to "mock" it without questioning whether there's value in having the mock. It gets messy since the only true measure of "works" is "does it communicate with this resources that's outside our control".

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The pytest plugin for VCR looks like an easy solution. However, I leave this to the main developers because it adds new dependencies to cartopy testing.

typename = 'collectif:t_ser_l93'
feature = cfeature.WFSFeature(url, typename, edgecolor='red')
ax.add_feature(feature)
return ax.figure