Unstructured Triangular Grid Visualization

Introduction

In this lab, we will create a triangular 3D contour plot using Matplotlib. This plot is useful for visualizing unstructured triangular grids. We will be using the same data as in the second plot of trisurf3d_2.

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Skills Graph

Import necessary libraries

We will start by importing the necessary libraries for this lab, which include Matplotlib and NumPy.

import matplotlib.pyplot as plt
import numpy as np
import matplotlib.tri as tri

Define variables

We will define the variables that we will use to create our plot. These variables include the number of angles, number of radii, and the minimum radius.

n_angles = 48
n_radii = 8
min_radius = 0.25

Create mesh and compute x, y, z

We will create the mesh in polar coordinates and compute x, y, z using the defined variables.

radii = np.linspace(min_radius, 0.95, n_radii)
angles = np.linspace(0, 2*np.pi, n_angles, endpoint=False)
angles = np.repeat(angles[..., np.newaxis], n_radii, axis=1)
angles[:, 1::2] += np.pi/n_angles

x = (radii*np.cos(angles)).flatten()
y = (radii*np.sin(angles)).flatten()
z = (np.cos(radii)*np.cos(3*angles)).flatten()

Create custom triangulation

We will create a custom triangulation using the x and y coordinates.

triang = tri.Triangulation(x, y)

Mask off unwanted triangles

We will mask off the unwanted triangles using the mean of the x and y coordinates.

triang.set_mask(np.hypot(x[triang.triangles].mean(axis=1),
                         y[triang.triangles].mean(axis=1))
                < min_radius)

Create 3D contour plot

We will create a 3D contour plot using the created triangulation and the z coordinates. We will also customize the view angle so it's easier to understand the plot.

ax = plt.figure().add_subplot(projection='3d')
ax.tricontour(triang, z, cmap=plt.cm.CMRmap)
ax.view_init(elev=45.)
plt.show()

Summary

In this lab, we created a triangular 3D contour plot using Matplotlib. We went through the steps of importing the necessary libraries, defining variables, creating a mesh, creating a custom triangulation, masking off unwanted triangles, and creating the 3D contour plot.