VTK到Maplotlib使用numpy的 [英] VTK to Maplotlib using Numpy

问题描述

我想从 VTK 文件与他们的网格坐标沿着提取一些数据（例如标量），然后在 Matplotlib 处理。问题是我不知道如何抓住从VTK文件中的点/单元格数据（通过给标量的名字，例如），并使用它们加载到一个 numpy的阵列 vtk_to_numpy

I want to extract some data (e.g. scalars) from a VTK file along with their coordinates on the grid then process it in Matplotlib. The problem is I dont know how to grab the point/cell data from the VTK file (by giving the name of the scalar, for instance) and load them into a numpy array using vtk_to_numpy

我的code应该是这样的：

My code should look like:

import matplotlib.pyplot as plt
from scipy.interpolate import griddata
import numpy as np
from vtk import *
from vtk.util.numpy_support import vtk_to_numpy

# load input data
reader = vtk.vtkXMLUnstructuredGridReader()
reader.SetFileName("my_input_data.vtk")
reader.Update()

(...missing steps)

# VTK to Numpy
my_numpy_array = vtk_to_numpy(...arguments ?)

#Numpy to Matplotlib (after converting my_numpy_array to x,y and z)
CS = plt.contour(x,y,z,NbLevels)
...

PS：我知道，的Paraview 可以做的任务，但我想后期处理，而无需打开的Paraview一些数据。任何帮助AP preciated

PS:I know that Paraview could do the task, but I am trying post process some data without having to open Paraview. Any help is appreciated

修改1

我发现这个 PDF教程要学会处理VTK的基础知识非常有用文件

I found this pdf tutorial to be very useful to learn the basics of handling VTK files

推荐答案

我终于想通办法（也许不是最佳）。这里的例子是轮廓绘制从VTK文件中提取的温度场：

I finally figured a way (maybe not the optimal) that does the job. The example here is contour plotting a temperature field extracted from a vtk file:

import matplotlib.pyplot as plt
from scipy.interpolate import griddata
import numpy as np
import vtk
from vtk.util.numpy_support import vtk_to_numpy

# load a vtk file as input
reader = vtk.vtkXMLUnstructuredGridReader()
reader.SetFileName("my_input_data.vtk")
reader.Update()

# Get the coordinates of nodes in the mesh
nodes_vtk_array= reader.GetOutput().GetPoints().GetData()

#The "Temperature" field is the third scalar in my vtk file
temperature_vtk_array = reader.GetOutput().GetPointData().GetArray(3)

#Get the coordinates of the nodes and their temperatures
nodes_nummpy_array = vtk_to_numpy(nodes_vtk_array)
x,y,z= nodes_nummpy_array[:,0] , nodes_nummpy_array[:,1] , nodes_nummpy_array[:,2]

temperature_numpy_array = vtk_to_numpy(temperature_vtk_array)
T = temperature_numpy_array

#Draw contours
npts = 100
xmin, xmax = min(x), max(x)
ymin, ymax = min(y), max(y)

# define grid
xi = np.linspace(xmin, xmax, npts)
yi = np.linspace(ymin, ymax, npts)
# grid the data
Ti = griddata((x, y), T, (xi[None,:], yi[:,None]), method='cubic')  

## CONTOUR: draws the boundaries of the isosurfaces
CS = plt.contour(xi,yi,Ti,10,linewidths=3,cmap=cm.jet) 

## CONTOUR ANNOTATION: puts a value label
plt.clabel(CS, inline=1,inline_spacing= 3, fontsize=12, colors='k', use_clabeltext=1)

plt.colorbar() 
plt.show() 

这篇关于VTK到Maplotlib使用numpy的的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！