Computing Mesh Quality

Note

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Computing Mesh Quality#

Leverage powerful VTK algorithms for computing mesh quality.

Here we will use the cell_quality() filter to compute the cell qualities. The following quality measures are available for various cell types:

Cell Quality Measures#

Measure

TRIANGLE

QUAD

TETRA

HEXAHEDRON

WEDGE

PYRAMID

area

aspect_frobenius

aspect_gamma

aspect_ratio

collapse_ratio

condition

diagonal

dimension

distortion

jacobian

max_angle

max_aspect_frobenius

max_edge_ratio

med_aspect_frobenius

min_angle

oddy

radius_ratio

relative_size_squared

scaled_jacobian

shape

shape_and_size

shear

shear_and_size

skew

stretch

taper

volume

warpage

 

from __future__ import annotations

import pyvista as pv
from pyvista import examples

Triangle Cell Quality#

Load a PolyData mesh and decimate() it to show coarse TRIANGLE cells for the example. Here we use download_cow().

mesh = examples.download_cow().triangulate().decimate(0.7)

Compute some valid measures for triangle cells.

measures = ['area', 'shape', 'min_angle', 'max_angle']
qual = mesh.cell_quality(measures)

Plot the meshes in subplots for comparison. We define a custom method for adding each mesh to each subplot.

def add_mesh(plotter, mesh, scalars=None, cmap='bwr', show_edges=True):
    # Create a copy to avoid reusing the same mesh in different plots
    copied = mesh.copy(deep=False)
    plotter.add_mesh(copied, scalars=scalars, cmap=cmap, show_edges=show_edges)
    plotter.view_xy()


pl = pv.Plotter(shape=(2, 2))
pl.link_views()
pl.subplot(0, 0)
add_mesh(pl, qual, scalars=measures[0])
pl.subplot(0, 1)
add_mesh(pl, qual, scalars=measures[1])
pl.subplot(1, 0)
add_mesh(pl, qual, scalars=measures[2])
pl.subplot(1, 1)
add_mesh(pl, qual, scalars=measures[3])
pl.show()
mesh quality

Quality measures like 'volume' do not apply to 2D cells, and a null value of -1 is returned.

qual = mesh.cell_quality(['volume'])
qual.get_data_range('volume')

(np.float64(-1.0), np.float64(-1.0))

Tetrahedron Cell Quality#

Load a mesh with TETRA cells. Here we use download_letter_a().

mesh = examples.download_letter_a()

Plot some valid quality measures for tetrahedral cells.

measures = ['volume', 'collapse_ratio', 'jacobian', 'scaled_jacobian']
qual = mesh.cell_quality(measures)

pl = pv.Plotter(shape=(2, 2))
pl.link_views()
pl.subplot(0, 0)
add_mesh(pl, qual, scalars=measures[0])
pl.subplot(0, 1)
add_mesh(pl, qual, scalars=measures[1])
pl.subplot(1, 0)
add_mesh(pl, qual, scalars=measures[2])
pl.subplot(1, 1)
add_mesh(pl, qual, scalars=measures[3])
pl.show()
mesh quality

Tags: filter

Total running time of the script: (0 minutes 0.893 seconds)

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