Coordinate reference systems in Cartopy
---------------------------------------
The :class:`cartopy.crs.CRS` class is the very core of cartopy, all coordinate reference systems
in cartopy have :class:`~cartopy.crs.CRS` as a parent class, meaning all projections have
the interface described below.
.. autoclass:: cartopy.crs.CRS(proj4_params, globe=None)
:members:
.. data:: globe
The :class:`~cartopy.crs.Globe` instance of this CRS.
The :class:`~cartopy.crs.Globe` class is used to encapsulate the underlying sphere or ellipsoid of any cartopy CRS.
All CRSs have an associated :class:`~cartopy.crs.Globe`, though often it is just the default :class:`~cartopy.crs.Globe`
which represents the reference ellipsoid (i.e. "wgs84").
.. autoclass:: cartopy.crs.Globe(datum=None, ellipse='WGS84', semimajor_axis=None, semiminor_axis=None, flattening=None, inverse_flattening=None, towgs84=None)
:members:
:exclude-members: to_proj4_params
The most common :class:`~cartopy.crs.CRS` subclass is itself another abstract class;
the :class:`cartopy.crs.Projection` class represents a 2 dimensional coordinate system
which could be drawn directly as a map (i.e. on a flat piece of paper). :class:`~cartopy.crs.Projection` is the parent class of
all projections in the :ref:`cartopy_projections`.
.. autoclass:: cartopy.crs.Projection
:members:
There are a few non-:class:`~cartopy.crs.Projection` subclasses. These represent
coordinate reference systems which are 3 dimensional and could not be drawn directly on a piece of paper.
.. autoclass:: cartopy.crs.Geodetic(globe=None)
.. autoclass:: cartopy.crs.Geocentric(globe=None)
.. autoclass:: cartopy.crs.RotatedGeodetic
There is also a function for calling epsg.io with a specified code, returning the corresponding cartopy projection, see below.
.. autofunction:: cartopy.crs.epsg