我想在vtk（python）中制作均匀分布的球体

Question

正如你在标题中看到的，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＆＃34; Evenly distributing n points on a sphere＆＃34;这是一种创建均匀分布的球体的方法。通过该链接，我得到了均匀分布的球体的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的球体的x，y，z坐标，我也不能在vtk（python）上制作一个polydata ..

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polydata没有出现在我的vtk窗口， 我该怎么做才能解决这个问题？

-Tae Young。

Answer 1

干得好。现在您已经为球体多边形数据添加了点，我们需要从点生成一个曲面。我们使用vtkDelaunay3D过滤器执行此操作。它将生成四面体的3D网格。因此，要获得实际的球面，我们必须使用vtkDataSetSurfaceFilter提取曲面。这些完成如下：

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使这变得非常简单：

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)