# 1.0-cross-section-simple

Bane Sullivan
%matplotlib inline
from pyvista import set_plot_theme
set_plot_theme('document')

# #Geological Cross Section

Plot a geological cross section in 3D space.

We have a cross section PNG image and we know three coordinates along that section:

• This section goes from +200m to -2000m in vertical extent
• Coordinates of the start point: 32362837 5769796
• Coordinates of the bend: 32368424 5765456 (the bending point is indicated with a * "K" at around half the section)
• Coordinates of the end point: 32374114 5763507

Originally posted: https://github.com/pyvista/pyvista-support/issues/272

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

Parameters for cross section

zrng = [-2000, 200]
start = [32362837, 5769796]
bend = [
32368424,
5765456,
]  # (the bending point is indicated with a "K" at around half the section)
end = [32374114, 5763507]

Make a surface mesh representing that coverage/ This mesh consists of 6 points. Generate them: a-----b-----e | | | | | | d-----c-----f

a = start + [
zrng[1],
]
b = bend + [
zrng[1],
]
c = bend + [
zrng[0],
]
d = start + [
zrng[0],
]
e = end + [
zrng[1],
]
f = end + [
zrng[0],
]

Now make a poly data mesh of these points

points = np.array([a, b, c, d, e, f])
faces = np.array([4, 0, 1, 2, 3, 4, 1, 4, 5, 2])
surface = pv.PolyData(points, faces)

Map the texture to the mesh.

• We know the tcoords of a, d, e, & f, but not necessarily b & c
• to find them, scale by cell sizes:
• Get the width of the two cells to find those coords
w = surface.compute_cell_sizes()["Area"] / np.ptp(zrng)
tw = (w / np.sum(w))[0]

# Generate Tcoords now!
t_coords = np.array(
[
[0, 1],
[tw, 1],
[tw, 0],
[0, 0],
[1, 1],
[1, 0],
]
)
surface.t_coords = t_coords

path, _ = examples.downloads._download_file("geo-cross-section.png")
texture = pv.Texture(path)
cpos = [
surface.plot(texture=texture, cpos=cpos, show_edges=True)