python - 我想在 vtk (python) 中制作均匀分布的球体

Question

正如您在标题中看到的，我想在 vtk (python) 中制作均匀分布的球体

首先，我看到了这个链接“在球体上均匀分布 n 个点”，这是一种创建均匀分布球体的方法。通过那个链接，我得到了均匀分布球体的 x,y,z 坐标。

其次，这实际上不是我必须解决的问题。问题是即使我有均匀分布球体的 x,y,z 坐标，我也无法在 vtk(python)..

import numpy as np
import mpl_toolkits.mplot3d
import matplotlib.pyplot as plt
import vtk
from scipy.spatial import Delaunay

num_pts = 1000
indices = np.arange(0, num_pts, dtype=float) + 0.5

phi = np.arccos(1 - 2*indices/num_pts)
theta = np.pi * (1 + 5**0.5) * indices

x, y, z = np.cos(theta) * np.sin(phi), np.sin(theta) * np.sin(phi), np.cos(phi);

# x,y,z is coordination of evenly distributed shpere
# I will try to make poly data use this x,y,z 

points = vtk.vtkPoints()


for i in range(len(x)):
    array_point = np.array([x[i], y[i], z[i]] )
    points.InsertNextPoint(x[i],y[i],z[i])


#   tri = Delaunay(points) (Do I have to use this function??)

poly = vtk.vtkPolyData()
poly.SetPoints(points)

mapper = vtk.vtkPolyDataMapper()
mapper.SetInputData(poly)

actor = vtk.vtkActor()
actor.SetMapper(mapper)

ren = vtk.vtkRenderer()
ren.AddActor(actor)
renWin = vtk.vtkRenderWindow()
renWin.AddRenderer(ren)

iren = vtk.vtkRenderWindowInteractor()
iren.SetRenderWindow(renWin)

renWin.Render()
iren.Start()

代码没有抛出任何错误，但是我的 vtk 窗口中没有出现 polydata，我应该怎么做才能解决这个问题？

-泰英。

Answer 1

干得好。现在您已经将点添加到球体多数据中，我们需要从点中生成一个曲面。我们使用vtkDelaunay3D过滤器来做到这一点。它将生成四面体的 3D 网格。因此，为了得到一个实际的球面，我们必须使用vtkDataSetSurfaceFilter. 这些在下面完成：

import numpy as np
import vtk

num_pts = 1000
indices = np.arange(0, num_pts, dtype=float) + 0.5

phi = np.arccos(1 - 2*indices/num_pts)
theta = np.pi * (1 + 5**0.5) * indices

x, y, z = np.cos(theta) * np.sin(phi), np.sin(theta) * np.sin(phi), np.cos(phi);

# x,y,z is coordination of evenly distributed shpere
# I will try to make poly data use this x,y,z 

points = vtk.vtkPoints()


for i in range(len(x)):
    array_point = np.array([x[i], y[i], z[i]] )
    points.InsertNextPoint(x[i],y[i],z[i])

poly = vtk.vtkPolyData()
poly.SetPoints(points)

# To create surface of a sphere we need to use Delaunay triangulation
d3D = vtk.vtkDelaunay3D()
d3D.SetInputData( poly ) # This generates a 3D mesh

# We need to extract the surface from the 3D mesh
dss = vtk.vtkDataSetSurfaceFilter()
dss.SetInputConnection( d3D.GetOutputPort() )
dss.Update()

# Now we have our final polydata
spherePoly = dss.GetOutput()

mapper = vtk.vtkPolyDataMapper()
mapper.SetInputData(spherePoly)

actor = vtk.vtkActor()
actor.SetMapper(mapper)

ren = vtk.vtkRenderer()
ren.AddActor(actor)
renWin = vtk.vtkRenderWindow()
renWin.AddRenderer(ren)

iren = vtk.vtkRenderWindowInteractor()
iren.SetRenderWindow(renWin)

renWin.Render()
iren.Start()

Answer 2

PyVista使这变得非常容易：

import numpy as np
import pyvista as pv

num_pts = 1000
indices = np.arange(0, num_pts, dtype=float) + 0.5

phi = np.arccos(1 - 2*indices/num_pts)
theta = np.pi * (1 + 5**0.5) * indices

x =  np.cos(theta) * np.sin(phi) 
y = np.sin(theta) * np.sin(phi)
z = np.cos(phi)

point_cloud = pv.PolyData(np.c_[x, y, z])
surface = point_cloud.delaunay_3d().extract_surface()
surface.plot(show_edges=True, color=True, show_grid=True)