Plotting Glyphs (Vectors or PolyData)

Use vectors in a dataset to plot and orient glyphs/geometric objects.

import numpy as np
import pyvista as pv
from pyvista import examples

Example dataset with normals

mesh = examples.load_random_hills()

Glyphying can be done via the pyvista.DataSetFilters.glyph() filter

help(mesh.glyph)

Sometimes you might not want glyphs for every node in the input dataset. In this case, you can choose to build glyphs for a subset of the input dataset by using a merging tolerance. Here we specify a merging tolerance of five percent which equates to five percent of the bounding box’s length.

create a subset of arrows using the glyph filter

arrows = ...

p = pv.Plotter()
p.add_mesh(arrows, color="black")
p.add_mesh(mesh, scalars="Elevation", cmap="terrain", smooth_shading=True)
p.show()

A common approach is to load vectors directly to the mesh object and then access the pyvista.DataSet.arrows property to produce glyphs.

sphere = pv.Sphere(radius=3.14)

# make cool swirly pattern
vectors = np.vstack(
    (
        np.sin(sphere.points[:, 0]),
        np.cos(sphere.points[:, 1]),
        np.cos(sphere.points[:, 2]),
    )
).T
vectors

# add and scale
sphere["vectors"] = vectors * 0.3
sphere.set_active_vectors("vectors")

# plot just the arrows
sphere.arrows.plot()

Plot the arrows and the sphere.

p = pv.Plotter()
p.add_mesh(sphere.arrows, lighting=False, scalar_bar_args={"title": "Vector Magnitude"})
p.add_mesh(sphere, color="grey", ambient=0.6, opacity=0.5, show_edges=False)
p.show()