code: def delaunay3D(dataset, alpha=0, tol=None, boundary=True):
          
          deln = vtk.vtkDelaunay3D()
          deln.SetInputData(dataset)
          deln.SetAlpha(alpha)
          if tol:
              deln.SetTolerance(tol)
          deln.SetBoundingTriangulation(boundary)
          deln.Update()
          return deln.GetOutput()
docs: Create 3D Delaunay triangulation of input points.