.. DO NOT EDIT. .. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY. .. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE: .. "gallery/99_advanced_plots/p03_contour_based_fieldlines.py" .. LINE NUMBERS ARE GIVEN BELOW. .. only:: html .. note:: :class: sphx-glr-download-link-note :ref:`Go to the end ` to download the full example code. .. rst-class:: sphx-glr-example-title .. _sphx_glr_gallery_99_advanced_plots_p03_contour_based_fieldlines.py: Polarity-Inversion-Line Seeded Fieldlines ========================================== This example traces magnetic fieldlines seeded from the polarity inversion line (PIL) — the curve on the solar surface where the radial magnetic field :math:`B_r` changes sign. The PIL marks the boundary between open positive and negative flux and is a natural seed surface for displaying the global topology of the coronal field. It can be used to locate the apex of coronal arcades and/or highlight bald-patch topologies. The workflow exploits a key property of :class:`~pyvisual.core.mesh3d.SphericalMesh`: because it wraps a :class:`pyvista.RectilinearGrid` whose internal axes store :math:`(r, \theta, \phi)` directly, PyVista's :meth:`pyvista.DataSetFilters.contour` returns a :class:`pyvista.PolyData` whose ``points`` array is already in :math:`(r, \theta, \phi)` coordinates. This means the contour points can be passed straight to :func:`~mapflpy.scripts.run_fwdbwd_tracing` as ``launch_points`` without any intermediate coordinate conversion. See also :ref:`sphx_glr_gallery_02_stack_mesh_mixin_p03_fieldlines.py` for a general introduction to fieldline rendering, and :ref:`sphx_glr_gallery_99_advanced_plots_p01_combining_multiple_elements.py` for a broader scene that layers slices, contours, and fieldlines. .. GENERATED FROM PYTHON SOURCE LINES 28-35 .. code-block:: Python import numpy as np from mapflpy.scripts import run_fwdbwd_tracing from pyvisual import Plot3d from pyvisual.core.mesh3d import SphericalMesh from pyvisual.utils.data import fetch_datasets .. GENERATED FROM PYTHON SOURCE LINES 36-51 Load Data and Extract the Polarity Inversion Line --------------------------------------------------- Build a full :class:`~pyvisual.core.mesh3d.SphericalMesh` from the coronal :math:`B_r` HDF file. Index ``mesh[5, ...]`` selects a 2-D spherical shell at radial index 5 — a thin :class:`pyvista.RectilinearGrid` that spans the full :math:`(\\theta, \\phi)` domain at a fixed :math:`r`. The ellipsis (``...``) expands to fill the remaining two axes. :meth:`pyvista.DataSetFilters.contour` with ``isosurfaces=[0]`` then finds the iso-curve where :math:`B_r = 0` on that shell. The result is the polarity inversion line as a :class:`pyvista.PolyData` of line segments whose ``points`` array holds :math:`(r, \\theta, \\phi)` coordinates — because the internal axes of :class:`~pyvisual.core.mesh3d.SphericalMesh` *are* the spherical coordinates, not Cartesian positions. .. GENERATED FROM PYTHON SOURCE LINES 51-57 .. code-block:: Python mag_field = fetch_datasets("cor", ["br", "bt", "bp"]) mesh = SphericalMesh(mag_field.cor_br) neutraline = mesh[5, ...].contour(isosurfaces=[0]) .. GENERATED FROM PYTHON SOURCE LINES 58-77 Trace Fieldlines from the PIL ------------------------------ :func:`~mapflpy.scripts.run_fwdbwd_tracing` integrates the magnetic field in both the forward and backward directions from each seed point, so that every fieldline has footpoints on both the inner (:math:`r = 1\,R_{\\odot}`) and outer (:math:`r = 30\,R_{\\odot}`) boundaries. This bidirectional tracing is required for accurate polarity classification and ensures that closed fieldlines connecting two inner-boundary footpoints are also captured. ``launch_points=neutraline.points.T`` passes the PIL vertices directly as the :math:`(3, N)` seed array in :math:`(r, \\theta, \\phi)` order. No coordinate conversion is needed because the contour inherits the :class:`~pyvisual.core.mesh3d.SphericalMesh` coordinate convention. :func:`numpy.moveaxis` transposes the ``(M, 3, N)`` geometry array to :math:`(3, M, N)` so that unpacking with ``*`` feeds the three coordinate components directly to :meth:`~pyvisual.core.mixins.StackMeshMixin.add_fieldlines`. .. GENERATED FROM PYTHON SOURCE LINES 77-81 .. code-block:: Python traces = run_fwdbwd_tracing(*mag_field, launch_points=neutraline.points.T, context='fork') r, t, p = np.moveaxis(traces.geometry, 1, 0) .. GENERATED FROM PYTHON SOURCE LINES 82-94 Render the Scene ----------------- Three layers are combined in a single :class:`~pyvisual.core.plot3d.Plot3d` scene: - The radial shell ``mesh[5, ...]`` coloured by :math:`B_r`, providing context for the polarity structure at the seed radius. - The PIL rendered as a white tube, showing the exact seed curve. - The fieldline bundle, each line assigned a random hue via ``coloring='random'``, illustrating the global connectivity of the coronal field anchored at the polarity boundary. .. GENERATED FROM PYTHON SOURCE LINES 94-103 .. code-block:: Python plotter = Plot3d() plotter.show_axes() plotter.add_sun() plotter.add_mesh(mesh[5, ...], cmap='seismic', clim=(-1e-1, 1e-1), opacity=0.5, show_scalar_bar=False) plotter.add_mesh(neutraline, color='white', line_width=3, render_lines_as_tubes=True) plotter.add_fieldlines(r, t, p, coloring='random', line_width=1, show_scalar_bar=False) plotter.observer_focus = 0, 0, 0 plotter.observer_fov_view = 10 plotter.show() .. tab-set:: .. tab-item:: Static Scene .. image-sg:: /gallery/99_advanced_plots/images/sphx_glr_p03_contour_based_fieldlines_001.png :alt: p03 contour based fieldlines :srcset: /gallery/99_advanced_plots/images/sphx_glr_p03_contour_based_fieldlines_001.png :class: sphx-glr-single-img .. tab-item:: Interactive Scene .. offlineviewer:: /Users/rdavidson/MHDweb/pyvisual/docs/source/gallery/99_advanced_plots/images/sphx_glr_p03_contour_based_fieldlines_001.vtksz .. rst-class:: sphx-glr-timing **Total running time of the script:** (0 minutes 18.963 seconds) .. _sphx_glr_download_gallery_99_advanced_plots_p03_contour_based_fieldlines.py: .. only:: html .. container:: sphx-glr-footer sphx-glr-footer-example .. container:: sphx-glr-download sphx-glr-download-jupyter :download:`Download Jupyter notebook: p03_contour_based_fieldlines.ipynb ` .. container:: sphx-glr-download sphx-glr-download-python :download:`Download Python source code: p03_contour_based_fieldlines.py ` .. container:: sphx-glr-download sphx-glr-download-zip :download:`Download zipped: p03_contour_based_fieldlines.zip ` .. only:: html .. rst-class:: sphx-glr-signature `Gallery generated by Sphinx-Gallery `_