Oblique Mercator class

lib/cartopy/crs.py

@@ -3089,6 +3089,71 @@ def y_limits(self):
         return self._y_limits
 
 
+class ObliqueMercator(Projection):
+    """
+    An Oblique Mercator projection.
+
+    """
+    _wrappable = True
+
+    def __init__(self, central_longitude=0.0, central_latitude=0.0,
+                 false_easting=0.0, false_northing=0.0,
+                 scale_factor=1.0, azimuth=0.0, globe=None):
+        """
+        Parameters
+        ----------
+        central_longitude: optional
+            The true longitude of the central meridian in degrees.
+            Defaults to 0.
+        central_latitude: optional
+            The true latitude of the planar origin in degrees. Defaults to 0.
+        false_easting: optional
+            X offset from the planar origin in metres. Defaults to 0.
+        false_northing: optional
+            Y offset from the planar origin in metres. Defaults to 0.
+        scale_factor: optional
+            Scale factor at the central meridian. Defaults to 1.
+        azimuth: optional
+            Azimuth of centerline clockwise from north at the center point of
+            the centre line. Defaults to 0.
+
+        globe: optional
+            An instance of :class:`cartopy.crs.Globe`. If omitted, a default
+            globe is created.
+
+        Notes
+        -----
+        The 'Rotated Mercator' projection can be achieved using Oblique
+        Mercator with `azimuth` ``=90``.
+
+        """
+
+        proj4_params = [('proj', 'omerc'), ('lonc', central_longitude),
+                        ('lat_0', central_latitude), ('k', scale_factor),
+                        ('x_0', false_easting), ('y_0', false_northing),
+                        ('alpha', azimuth), ('units', 'm')]
+
+        super().__init__(proj4_params, globe=globe)
+
+        self.threshold = 1e4
+
+    @property
+    def boundary(self):
+        x0, x1 = self.x_limits
+        y0, y1 = self.y_limits
+        return sgeom.LinearRing([(x0, y0), (x0, y1),
+                                 (x1, y1), (x1, y0),
+                                 (x0, y0)])
+
+    @property
+    def x_limits(self):
+        return (-2e7, 2e7)
+
+    @property
+    def y_limits(self):
+        return (-1e7, 1e7)
+
+
 class _BoundaryPoint:
     def __init__(self, distance, kind, data):
         """

lib/cartopy/mpl/gridliner.py

@@ -45,6 +45,7 @@
     cartopy.crs.LambertConformal,
     cartopy.crs.TransverseMercator,
     cartopy.crs.Gnomonic,
+    cartopy.crs.ObliqueMercator,
 )