marching_cube_from_numpy_array.py

import numpy as np
import vtk
import pyvista as pv
from vtk.util import numpy_support
# from vtk.numpy_interface import dataset_adapter as dsa

data = np.zeros((50, 50, 50))
data[20:30, 20:30, 20:30] = 1

data_vtk = numpy_support.numpy_to_vtk(
    data.ravel(), deep=True, array_type=vtk.VTK_DOUBLE
)
imdata = vtk.vtkImageData()
imdata.SetDimensions(data.shape)
imdata.SetSpacing([1, 1, 1])
imdata.SetOrigin([0, 0, 0])
imdata.GetPointData().SetScalars(data_vtk)

mc = vtk.vtkMarchingCubes()
mc.SetInputData(imdata)
mc.SetValue(0, 0.5)
mc.Update()

polydata = mc.GetOutput()
# points = dsa.WrapDataObject(polydata).Points

mesh = pv.PolyData(polydata)
mesh.plot()