.. _sphx_glr_api_gallery_geometry_intersections:

Point-in-polygon
------------------------------------------------

Ray casting and the Jordan curve theorem, with crossings found by
segment intersection.


.. raw:: html

  <div id='sg-tag-list' class='sphx-glr-tag-list'></div>


.. raw:: html

    <div class="sphx-glr-thumbnails">

.. thumbnail-parent-div-open

.. raw:: html

    <div class="sphx-glr-thumbcontainer" tooltip="A simple closed polygon splits the plane into an inside and an outside (the Jordan curve theorem). A ray cast from a point crosses the boundary an odd number of times exactly when the point is inside. The crossings are found edge by edge with segment_intersection, and their parity agrees with point_in_polygon on a concave, spiral-like polygon.">

.. only:: html

  .. image:: /api/gallery/geometry/intersections/images/thumb/sphx_glr_plot_01_jordan_ray_casting_thumb.png
    :alt:

  :doc:`/api/gallery/geometry/intersections/plot_01_jordan_ray_casting`

.. raw:: html

      <div class="sphx-glr-thumbnail-title">The Jordan curve theorem and ray casting: inside or outside?</div>
    </div>


.. thumbnail-parent-div-close

.. raw:: html

    </div>


.. toctree::
   :hidden:

   /api/gallery/geometry/intersections/plot_01_jordan_ray_casting