Improve CRS support in OAMaps

docs/source/publishing/ogcapi-maps.rst

@@ -118,14 +118,14 @@ required.  An optional style name can be defined via `options.style`.
 
 .. note::
   According to the `Standard <https://docs.ogc.org/is/20-058/20-058.html#_5df53b56-5468-4c9d-acac-6abfddd83ccf>`_, OGC API - Maps
-  supports a `crs` parameter, expressed as an uri. Currently, this provider supports CRS84, WGS84 and Web Mercator; for a matter of convenience, they can be expressed in
-  a number of different ways, other than the uri format.
-
-  - `EPSG:4326`
-  - `EPSG:3857`
-  - `4326`
-  - `3857`,
-  - `CRS84`
+  supports a `crs` and `bbox-crs` parameters, expressed as an uri or a CURIE. Currently, this provider supports CRS84 and various CRS from the EPSG namespace; for a matter of convenience, they can be expressed
+  also as unsafe CURIEs.
+
+  - `http://www.opengis.net/def/crs/EPSG/0/4326`
+  - `[EPSG:4326]`
+  - `EPSG:4326` (unsafe)
+  - `CRS:84` (unsafe, for compatibility with WMS)
+  - `OGC:CRS84` (unsafe)
 
   If `crs` is not provided, the server will default to the `storage_crs`; in case it does not exist, the default is `CRS84`.
   If `crs-bbox` is not provided, it will default to `CRS84`. If the `bbox` is not provided, it will default to `-180, -90, 180, 90`.

pygeoapi/api/maps.py

@@ -44,7 +44,7 @@
 import logging
 from typing import Tuple
 
-from pygeoapi.crs import transform_bbox, DEFAULT_CRS
+from pygeoapi.crs import transform_bbox, DEFAULT_CRS, get_uri
 from pygeoapi.formats import F_JSON, FORMAT_TYPES
 from pygeoapi.openapi import get_oas_30_parameters
 from pygeoapi.plugin import load_plugin
@@ -64,18 +64,6 @@
 
 DEFAULT_BBOX = [-180, -90, 180, 90]  # CRS84
 
-CRS_CODES = {
-    '4326': 'http://www.opengis.net/def/crs/EPSG/0/4326',
-    '3857': 'http://www.opengis.net/def/crs/EPSG/0/3857',
-    'CRS84': 'http://www.opengis.net/def/crs/OGC/1.3/CRS84',
-    'http://www.opengis.net/def/crs/EPSG/0/4326': 'http://www.opengis.net/def/crs/EPSG/0/4326',  # noqa
-    'http://www.opengis.net/def/crs/EPSG/0/3857': 'http://www.opengis.net/def/crs/EPSG/0/3857',  # noqa
-    'http://www.opengis.net/def/crs/OGC/1.3/CRS84': 'http://www.opengis.net/def/crs/OGC/1.3/CRS84', # noqa
-    'EPSG:4326': 'http://www.opengis.net/def/crs/EPSG/0/4326',
-    'EPSG:3857': 'http://www.opengis.net/def/crs/EPSG/0/3857',
-    'CRS:84': 'http://www.opengis.net/def/crs/OGC/1.3/CRS84',
-}
-
 
 def get_collection_map(api: API, request: APIRequest,
                        dataset: str, style: str | None = None
@@ -123,11 +111,11 @@ def get_collection_map(api: API, request: APIRequest,
     # if it does not exist or is not supported, use CRS84.
     try:
         if 'crs' not in request.params:
-            query_args['crs'] = CRS_CODES.get(collection_def.get('storage_crs',
-                                              DEFAULT_CRS), DEFAULT_CRS)
+            query_args['crs'] = collection_def.get('storage_crs',
+                                                   DEFAULT_CRS)
         else:
-            query_args['crs'] = CRS_CODES.get(request.params['crs'],
-                                              DEFAULT_CRS)
+            query_args['crs'] = get_uri(request.params['crs'])
+
     except KeyError:
         query_args['crs'] = DEFAULT_CRS
 
@@ -138,8 +126,7 @@ def get_collection_map(api: API, request: APIRequest,
         if 'bbox-crs' not in request.params:
             query_args['bbox-crs'] = DEFAULT_CRS
         else:
-            query_args['bbox-crs'] = CRS_CODES.get(request.params['bbox-crs'],
-                                                   DEFAULT_CRS)
+            query_args['bbox-crs'] = get_uri(request.params['bbox-crs'])
     except KeyError:
         query_args['bbox-crs'] = DEFAULT_CRS
 
@@ -190,9 +177,9 @@ def get_collection_map(api: API, request: APIRequest,
 
     # the transformer function expects the crs to be in a uri format
     if query_args['bbox-crs'] != query_args['crs']:
-        LOGGER.debug(f'Reprojecting bbox CRS: {query_args["crs"]}')
         bbox = transform_bbox(bbox, query_args['bbox-crs'],
                               query_args['crs'], always_xy=True)
+        LOGGER.debug(f'Transformed bbox: {bbox}')
     query_args['bbox'] = bbox
 
     LOGGER.debug('Processing datetime parameter')

pygeoapi/crs.py

@@ -3,6 +3,7 @@
 # Authors: Tom Kralidis <tomkralidis@gmail.com>
 #          Just van den Broecke <justb4@gmail.com>
 #
+# Copyright (c) 2026 Joana Simoes
 # Copyright (c) 2025 Tom Kralidis
 # Copyright (c) 2025 Just van den Broecke
 #
@@ -47,6 +48,7 @@
     shape as geojson_to_geom,
     mapping as geom_to_geojson
 )
+from urllib.parse import urlparse
 
 LOGGER = logging.getLogger(__name__)
 
@@ -120,6 +122,96 @@ def get_supported_crs_list(
     return supported_crs_list
 
 
+def get_uri(crs: str) -> str:
+    """
+    Parse a uri from a uri or a curie
+
+    :param crs: Uniform resource identifier of the coordinate
+                reference system. In accordance with
+                https://docs.ogc.org/pol/09-048r5.html#_naming_rule
+                Or a safe, or unsafe curie
+                https://docs.ogc.org/DRAFTS/20-024.html#conventions-curies
+
+    :raises `CRSError`: Error raised if no CRS could be identified from the
+        URI.
+
+    :returns: `crs uri` matching the input CRS.
+    """
+
+    try:
+        crs = crs.lower()
+        result = urlparse(crs)
+
+        # If it is a uri, check if it is valid
+        LOGGER.debug(f'Attempt to parse a uri: {crs}')
+
+        if result.scheme not in ['http', 'https']:
+            raise CRSError('Invalid uri scheme')
+        if result.netloc is None or result.netloc != 'www.opengis.net':
+            raise CRSError('Invalid uri prefix')
+
+        path_el = [p for p in result.path.split('/') if p]
+
+        # Check if the path uri contains the relevant fragments
+        if len(path_el
+               ) != 5 or path_el[0] != 'def' or path_el[1] != 'crs' or path_el[2] not in ['epsg', 'ogc']: # noqa
+            raise CRSError('Invalid uri fragments')
+
+        return crs
+
+    except CRSError:
+        try:
+            # Parse safe CURIE
+            curie = crs.strip('[]')
+            LOGGER.debug(f'Attempt to parse a curie: {curie}')
+
+            # We support all EPSG codes and CRS84
+            if curie not in ['crs:84', 'ogc:crs84']:
+                [curie_auth, curie_code] = curie.split(':')
+                if len(curie.split(':')) != 2 or (curie_auth != 'epsg'):
+                    raise CRSError('Unsupported CRS')
+
+                return f'http://www.opengis.net/def/crs/EPSG/0/{curie_code}'
+            else:
+                return 'http://www.opengis.net/def/crs/OGC/1.3/CRS84'
+
+        except CRSError as e:
+            return e
+
+
+def get_curie(crs: str) -> str:
+    """
+    Get a WMS compatible CRS CURIE from a uri
+
+    :param crs: Uniform resource identifier of the coordinate
+                reference system. In accordance with
+                https://docs.ogc.org/pol/09-048r5.html#_naming_rule
+
+    :raises `CRSError`: Error raised if no CRS could be identified from the
+        URI.
+
+    :returns: `WMS CURIE` matching the input uri.
+    """
+
+    try:
+        if not crs.startswith(("http://", "https://")):
+            raise CRSError('Not an uri')
+
+        crs = crs.lower()
+        path_el = [p for p in crs.split('/') if p]
+
+        # We support all EPSG codes and CRS84
+        if path_el[4] == 'epsg':
+            return f'EPSG:{path_el[6]}'
+        elif path_el[6] != 'crs84':
+            raise CRSError('Unsupported CRS')
+
+        return 'CRS:84'
+
+    except CRSError as e:
+        return e
+
+
 def get_crs(crs: Union[str, pyproj.CRS]) -> pyproj.CRS:
     """
     Get a `pyproj.CRS` instance from a CRS.

pygeoapi/provider/wms_facade.py

@@ -31,6 +31,10 @@
 import logging
 from urllib.parse import urlencode
 
+from pyproj.exceptions import CRSError
+
+from pygeoapi.crs import get_curie
+
 import pyproj
 import requests
 
@@ -43,13 +47,7 @@
     'png': 'image/png'
 }
 
-CRS_CODES = {
-    'http://www.opengis.net/def/crs/EPSG/0/4326': 'EPSG:4326',
-    'http://www.opengis.net/def/crs/EPSG/0/3857': 'EPSG:3857',
-    'http://www.opengis.net/def/crs/OGC/1.3/CRS84': 'CRS:84' # noqa
-}
-
-DEFAULT_CRS = 'CRS:84'
+DEFAULT_WMS_CRS = 'CRS:84'
 
 
 class WMSFacadeProvider(BaseProvider):
@@ -68,9 +66,9 @@ def __init__(self, provider_def):
 
         LOGGER.debug(f'pyproj version: {pyproj.__version__}')
 
-    def query(self, style=None, bbox=[-180, -90, 180, 90], width=500,
-              height=300, crs=DEFAULT_CRS, datetime_=None, transparent=True,
-              format_='png', **kwargs):
+    def query(self, style=None, bbox=[-180, -90, 180, 90],
+              width=500, height=300, crs=DEFAULT_WMS_CRS, datetime_=None,
+              transparent=True, format_='png', **kwargs):
         """
         Generate map
 
@@ -87,11 +85,18 @@ def query(self, style=None, bbox=[-180, -90, 180, 90], width=500,
         :returns: `bytes` of map image
         """
 
+        LOGGER.debug(f'bbox: {bbox}')
+
         self._transparent = 'TRUE'
 
         version = self.options.get('version', '1.3.0')
 
-        if version == '1.3.0' and CRS_CODES.get(crs) == 'EPSG:4326':
+        try:
+            wms_crs = get_curie(crs)
+        except CRSError:
+            wms_crs = DEFAULT_WMS_CRS
+
+        if version == '1.3.0' and wms_crs == 'EPSG:4326':
             bbox = [bbox[1], bbox[0], bbox[3], bbox[2]]
         bbox2 = ','.join(map(str, bbox))
 
@@ -104,7 +109,7 @@ def query(self, style=None, bbox=[-180, -90, 180, 90], width=500,
             'service': 'WMS',
             'request': 'GetMap',
             'bbox': bbox2,
-            crs_param: CRS_CODES.get(crs) or DEFAULT_CRS,
+            crs_param: wms_crs,
             'layers': self.options['layer'],
             'styles': self.options.get('style', 'default'),
             'width': width,

tests/provider/test_wms_facade_provider.py

@@ -31,6 +31,7 @@
 import pytest
 
 from pygeoapi.provider.wms_facade import WMSFacadeProvider
+from pygeoapi.provider.base import ProviderQueryError
 
 
 @pytest.fixture()
@@ -61,12 +62,9 @@ def test_crs_query(config):
     results1 = p.query(crs='http://www.opengis.net/def/crs/EPSG/0/4326')
     results2 = p.query(crs='http://www.opengis.net/def/crs/EPSG/0/3857')
 
-    print(results1)
-
     check_is_PNG(results1)
     check_is_PNG(results2)
 
-    # An invalid crs should default to default crs
-    results3 = p.query(crs='http://0000')
-
-    check_is_PNG(results3)
+    # An invalid uri triggers an error
+    with pytest.raises(ProviderQueryError):
+        p.query(crs='http://www.opengis.net/def/crs/FOO/0/9999')