.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "gallery/miscellanea/eccentric_ellipse.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        :ref:`Go to the end <sphx_glr_download_gallery_miscellanea_eccentric_ellipse.py>`
        to download the full example code

.. rst-class:: sphx-glr-example-title

.. _sphx_glr_gallery_miscellanea_eccentric_ellipse.py:


Displaying data on an eccentric ellipse
---------------------------------------

This example demonstrates plotting data on an eccentric ellipse. The data
plotted is a topography map of the asteroid Vesta. The map is actually an
image, which is defined on an equirectangluar projection relative to an
ellipse with a semi-major axis of 285 km and a semi-minor axis of 229 km.
The image is reprojected on-the-fly onto a geostationary projection with
matching eccentricity.

.. GENERATED FROM PYTHON SOURCE LINES 13-73



.. image-sg:: /gallery/miscellanea/images/sphx_glr_eccentric_ellipse_001.png
   :alt: eccentric ellipse
   :srcset: /gallery/miscellanea/images/sphx_glr_eccentric_ellipse_001.png
   :class: sphx-glr-single-img





.. code-block:: Python

    from io import BytesIO
    from urllib.request import urlopen

    import matplotlib.pyplot as plt
    import numpy as np
    from PIL import Image

    import cartopy.crs as ccrs


    def vesta_image():
        """
        Return an image of Vesta's topography.

        Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI

        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.

        """
        url = 'https://photojournal.jpl.nasa.gov/jpeg/PIA17037.jpg'
        img_handle = BytesIO(urlopen(url).read())
        raw_image = Image.open(img_handle)
        # The image is extremely high-resolution, which takes a long time to
        # plot. Sub-sampling reduces the time taken to plot while not
        # significantly altering the integrity of the result.
        smaller_image = raw_image.resize([raw_image.size[0] // 10,
                                          raw_image.size[1] // 10])
        img = np.asarray(smaller_image)
        # We define the semimajor and semiminor axes, but must also tell the
        # globe not to use the WGS84 ellipse, which is its default behaviour.
        img_globe = ccrs.Globe(semimajor_axis=285000., semiminor_axis=229000.,
                               ellipse=None)
        img_proj = ccrs.PlateCarree(globe=img_globe)
        img_extent = (-180, 180,
                      -90, 90)
        return img, img_globe, img_proj, img_extent


    def main():
        img, globe, crs, extent = vesta_image()
        projection = ccrs.Geostationary(globe=globe)

        fig = plt.figure()
        ax = fig.add_subplot(1, 1, 1, projection=projection)
        ax.imshow(img, transform=crs, extent=extent)
        fig.text(.075, .012, "Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI",
                 bbox={'facecolor': 'w', 'edgecolor': 'k'})
        plt.show()


    if __name__ == '__main__':
        main()


.. rst-class:: sphx-glr-timing

   **Total running time of the script:** (0 minutes 6.663 seconds)


.. _sphx_glr_download_gallery_miscellanea_eccentric_ellipse.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example

    .. container:: sphx-glr-download sphx-glr-download-jupyter

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

    .. container:: sphx-glr-download sphx-glr-download-python

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


.. only:: html

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

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_