.. DO NOT EDIT. .. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY. .. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE: .. "gallery/99_advanced_plots/p07_faux_volume_render.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_p07_faux_volume_render.py: Faux Volume Rendering ===================== This example demonstrates a technique for simulating volumetric rendering of coronal density by deconstructing a 3-D :class:`~pyvisual.core.mesh3d.SphericalMesh` into stacked semi-transparent radial shells — a *faux* volume that avoids the GPU memory cost of true volumetric rendering while still conveying the large-scale 3-D structure of the corona. The scene is animated along a Parker Solar Probe (PSP) trajectory obtained from the JPL Horizons ephemeris service via :func:`~pyvisual.utils.geometry.spacecraft_trajectory`, placing the virtual observer at each spacecraft position and framing the field of view in helioprojective angular coordinates using :attr:`~pyvisual.core.mixins.ObserverMixin.observer_los_view`. .. seealso:: :ref:`sphx_glr_gallery_04_observer_mixin_p02_orbit.py` Simpler orbit animation driven by a synthetic observer path. :ref:`sphx_glr_gallery_99_advanced_plots_p01_combining_multiple_elements.py` Multi-layer coronal scene that combines slices, contours, and fieldlines. .. GENERATED FROM PYTHON SOURCE LINES 27-37 .. code-block:: Python import os from pathlib import Path import numpy as np from pyvisual import Plot3d from pyvisual.core.mesh3d import SphericalMesh from pyvisual.utils.data import fetch_datasets from pyvisual.utils.geometry import spacecraft_trajectory .. GENERATED FROM PYTHON SOURCE LINES 39-52 Load Data --------- :func:`~pyvisual.utils.geometry.spacecraft_trajectory` queries the JPL Horizons ephemeris for Parker Solar Probe over a four-day window and returns a :class:`numpy.ndarray` of shape ``(3, N)`` whose rows are :math:`(r,\,\theta,\,\phi)` in the Carrington frame, sampled at the default 1-hour cadence. :func:`~pyvisual.utils.data.fetch_datasets` downloads (or loads from cache) the CR 2282 coronal density field on the :math:`1\text{–}30\,R_\odot` grid and returns the path to the HDF5 file as the named attribute ``cor_rho``. .. GENERATED FROM PYTHON SOURCE LINES 52-56 .. code-block:: Python trajectory = spacecraft_trajectory('psp', '2024-03-27', '2024-03-31') rho_file = fetch_datasets("cor", "rho").cor_rho .. rst-class:: sphx-glr-script-out .. code-block:: none INFO: Obtained JPL HORIZONS location for Parker Solar Probe (spacecraft) (-96) [sunpy.coordinates.ephemeris] .. GENERATED FROM PYTHON SOURCE LINES 57-77 Build the Faux Volume Representation -------------------------------------- The full density grid is loaded into a :class:`~pyvisual.core.mesh3d.SphericalMesh`. Indexing with ``[0, ...]`` selects the innermost radial shell at :math:`r \approx 1\,R_\odot` as a 2-D reference surface for the photospheric density. The remaining shells ``[1:, ...]`` form the 3-D coronal volume. Applying :obj:`numpy.log` via the mesh arithmetic suite compresses the large dynamic range of coronal density. :meth:`~pyvisual.core.mesh3d.SphericalMeshFilters.deconstruct` with ``method='slices'`` converts the 3-D :class:`pyvista.RectilinearGrid` into a collection of 2-D radial shell surfaces (via :func:`~pyvisual.core.mesh3d.build_slice_polydata`). Rendered with PyVista's ``'sigmoid_7'`` opacity transfer function, the stacked shells map low log-density regions to near-transparent and high log-density regions to near-opaque, mimicking the appearance of a volumetric render without requiring volume rendering hardware support. .. GENERATED FROM PYTHON SOURCE LINES 77-82 .. code-block:: Python mesh = SphericalMesh(rho_file) radial_slice_at_photosphere = mesh[0, ...] deconstructed_mesh_volume = np.log(mesh[1:, ...]).deconstruct(method='slices') .. GENERATED FROM PYTHON SOURCE LINES 83-108 Animate Along the Spacecraft Trajectory ---------------------------------------- The scene is assembled once and then animated by stepping the observer through each position in the PSP trajectory. Iterating over ``trajectory.T`` yields one :math:`(r,\,\theta,\,\phi)` column per time step, which is assigned directly to :attr:`~pyvisual.core.mixins.ObserverMixin.observer_position`. :attr:`~pyvisual.core.mixins.ObserverMixin.observer_los_view` frames the field of view as helioprojective angular extents :math:`(x_0,\, x_1,\, y_0,\, y_1)` in degrees. Re-applying the FOV at every frame ensures consistent framing as the spacecraft distance changes over the trajectory. .. warning:: The interactive 3-D viewer is omitted here because the deconstructed shell mesh is prohibitively large to embed in a browser. The animation is also generated and cached outside the sphinx-gallery pipeline: sphinx-gallery natively scrapes GIF output, but the 256-color palette limit of the GIF format renders poorly at this scene's dynamic range, so the movie is written as an MP4 via a separate pre-build step and embedded below using a raw HTML ``