.. _sphx_glr_gallery_geostationary.py:


Reprojecting images from a Geostationary projection
---------------------------------------------------

This example demonstrates Cartopy's ability to project images into the desired
projection on-the-fly. The image itself is retrieved from a URL and is loaded
directly into memory without storing it intermediately into a file. It
represents pre-processed data from the Spinning Enhanced Visible and Infrared
Imager onboard Meteosat Second Generation, which has been put into an image in
the data's native Geostationary coordinate system - it is then projected by
cartopy into a global Miller map.





.. image:: /gallery/images/sphx_glr_geostationary_001.png
    :align: center


.. rst-class:: sphx-glr-script-out

 Out::

    Retrieving image...
    Projecting and plotting image (this may take a while)...




|


.. code-block:: python


    try:
        from urllib2 import urlopen
    except ImportError:
        from urllib.request import urlopen
    from io import BytesIO

    import cartopy.crs as ccrs
    import matplotlib.pyplot as plt


    def geos_image():
        """
        Return a specific SEVIRI image by retrieving it from a github gist URL.

        Returns
        -------
        img : numpy array
            The pixels of the image in a numpy array.
        img_proj : cartopy CRS
            The rectangular coordinate system of the image.
        img_extent : tuple of floats
            The extent of the image ``(x0, y0, x1, y1)`` referenced in
            the ``img_proj`` coordinate system.
        origin : str
            The origin of the image to be passed through to matplotlib's imshow.

        """
        url = ('https://gist.github.com/pelson/5871263/raw/'
               'EIDA50_201211061300_clip2.png')
        img_handle = BytesIO(urlopen(url).read())
        img = plt.imread(img_handle)
        img_proj = ccrs.Geostationary(satellite_height=35786000)
        img_extent = [-5500000, 5500000, -5500000, 5500000]
        return img, img_proj, img_extent, 'upper'


    def main():
        fig = plt.figure()
        ax = fig.add_subplot(1, 1, 1, projection=ccrs.Miller())
        ax.coastlines()
        ax.set_global()
        print('Retrieving image...')
        img, crs, extent, origin = geos_image()
        print('Projecting and plotting image (this may take a while)...')
        ax.imshow(img, transform=crs, extent=extent, origin=origin, cmap='gray')
        plt.show()


    if __name__ == '__main__':
        main()

**Total running time of the script:** ( 3 minutes  8.683 seconds)



.. container:: sphx-glr-footer


  .. container:: sphx-glr-download

     :download:`Download Python source code: geostationary.py <geostationary.py>`



  .. container:: sphx-glr-download

     :download:`Download Jupyter notebook: geostationary.ipynb <geostationary.ipynb>`

.. rst-class:: sphx-glr-signature

    `Generated by Sphinx-Gallery <https://sphinx-gallery.readthedocs.io>`_