.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "tutorial/02_mesh/exercises/d_create-tri-surface.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

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

        :ref:`Go to the end <sphx_glr_download_tutorial_02_mesh_exercises_d_create-tri-surface.py>`
        to download the full example code or to run this example in your browser via Binder

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

.. _sphx_glr_tutorial_02_mesh_exercises_d_create-tri-surface.py:


.. _triangulated_surface_exercises:

Create Triangulated Surface
~~~~~~~~~~~~~~~~~~~~~~~~~~~

Create a surface from a set of points through a Delaunay triangulation.

.. note::
    We will use a filter from PyVista to perform our triangulation: `delaunay_2d <https://docs.pyvista.org/api/core/_autosummary/pyvista.PolyData.delaunay_2d.html>`_.

.. GENERATED FROM PYTHON SOURCE LINES 12-16

.. code-block:: Python


    import numpy as np
    import pyvista as pv


.. GENERATED FROM PYTHON SOURCE LINES 17-21

Simple Triangulations
+++++++++++++++++++++

First, create some points for the surface.

.. GENERATED FROM PYTHON SOURCE LINES 21-34

.. code-block:: Python


    # Define a simple Gaussian surface
    n = 20
    x = np.linspace(-200, 200, num=n) + np.random.uniform(-5, 5, size=n)
    y = np.linspace(-200, 200, num=n) + np.random.uniform(-5, 5, size=n)
    xx, yy = np.meshgrid(x, y)
    A, b = 100, 100
    zz = A * np.exp(-0.5 * ((xx / b) ** 2.0 + (yy / b) ** 2.0))

    # Get the points as a 2D NumPy array (N by 3)
    points = np.c_[xx.reshape(-1), yy.reshape(-1), zz.reshape(-1)]
    points[0:5, :]


.. GENERATED FROM PYTHON SOURCE LINES 35-37

Now use those points to create a point cloud PyVista data object. This will
be encompassed in a :class:`pyvista.PolyData` object.

.. GENERATED FROM PYTHON SOURCE LINES 37-42

.. code-block:: Python


    # simply pass the numpy points to the PolyData constructor
    cloud = ...
    cloud.plot(point_size=15)


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Now that we have a PyVista data structure of the points, we can perform a
triangulation to turn those boring discrete points into a connected surface.
See :func:`pyvista.UnstructuredGridFilters.delaunay_2d`.

.. GENERATED FROM PYTHON SOURCE LINES 46-48

.. code-block:: Python

    help(cloud.delaunay_2d)


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Apply the ``delaunay_2d`` filter.

.. GENERATED FROM PYTHON SOURCE LINES 50-57

.. code-block:: Python


    surf = ...

    # And plot it with edges shown
    surf.plot(show_edges=True)



.. GENERATED FROM PYTHON SOURCE LINES 58-60

Clean Edges & Triangulations
++++++++++++++++++++++++++++

.. GENERATED FROM PYTHON SOURCE LINES 60-73

.. code-block:: Python


    # Create the points to triangulate
    x = np.arange(10, dtype=float)
    xx, yy, zz = np.meshgrid(x, x, [0])
    points = np.column_stack((xx.ravel(order="F"), yy.ravel(order="F"), zz.ravel(order="F")))
    # Perturb the points
    points[:, 0] += np.random.rand(len(points)) * 0.3
    points[:, 1] += np.random.rand(len(points)) * 0.3

    # Create the point cloud mesh to triangulate from the coordinates
    cloud = pv.PolyData(points)
    cloud


.. GENERATED FROM PYTHON SOURCE LINES 74-76

.. code-block:: Python

    cloud.plot(cpos="xy")


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Run the triangulation on these points

.. GENERATED FROM PYTHON SOURCE LINES 78-81

.. code-block:: Python

    surf = cloud.delaunay_2d()
    surf.plot(cpos="xy", show_edges=True)


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Note that some of the outer edges are unconstrained and the triangulation
added unwanted triangles. We can mitigate that with the ``alpha`` parameter.

.. GENERATED FROM PYTHON SOURCE LINES 84-87

.. code-block:: Python

    surf = cloud.delaunay_2d(alpha=...)
    surf.plot(cpos="xy", show_edges=True)


.. GENERATED FROM PYTHON SOURCE LINES 88-95

.. raw:: html

    <center>
      <a target="_blank" href="https://colab.research.google.com/github/pyvista/pyvista-tutorial/blob/gh-pages/notebooks/tutorial/02_mesh/exercises/d_create-tri-surface.ipynb">
        <img src="https://colab.research.google.com/assets/colab-badge.svg" alt="Open In Colab"/ width="150px">
      </a>
    </center>


.. _sphx_glr_download_tutorial_02_mesh_exercises_d_create-tri-surface.py:

.. only:: html

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

    .. container:: binder-badge

      .. image:: images/binder_badge_logo.svg
        :target: https://mybinder.org/v2/gh/pyvista/pyvista-tutorial/gh-pages?urlpath=lab/tree/notebooks/tutorial/02_mesh/exercises/d_create-tri-surface.ipynb
        :alt: Launch binder
        :width: 150 px

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

      :download:`Download Jupyter notebook: d_create-tri-surface.ipynb <d_create-tri-surface.ipynb>`

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

      :download:`Download Python source code: d_create-tri-surface.py <d_create-tri-surface.py>`


.. only:: html

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

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