Coordinate reference systems ---------------------------- 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 :members: :noindex: .. 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 :members: :exclude-members: to_proj4_params :noindex: 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: :noindex: 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 :noindex: .. autoclass:: cartopy.crs.Geocentric :noindex: .. autoclass:: cartopy.crs.RotatedGeodetic :noindex: There is also a function for calling epsg.io with a specified code, returning the corresponding cartopy projection, see below. .. autofunction:: cartopy.crs.epsg :noindex: