如何在python中编写vtk卷

我找到了这段代码，并用它用DICOM文件的2D切片制作了一个体积文件。

# Read 
reader = vtk.vtkDICOMImageReader()
reader.SetDirectoryName(folder)
reader.Update()

# Set up the Mapper
mapper = vtk.vtkFixedPointVolumeRayCastMapper()
mapper.SetInputConnection(reader.GetoutputPort())
mapper.SetBlendModetoMaximumIntensity()

# Set up the Property
colorFunc = vtk.vtkColorTransferFunction()
colorFunc.AddRGBSegment(0.0,1.0,255.0,255.0)
opacityFunc = vtk.vtkPiecewiseFunction()
opacityWindow = 4096
opacityLevel  = 2048
opacityFunc.AddSegment(opacityLevel - 0.5*opacityWindow,0.0,opacityLevel + 0.5*opacityWindow,1.0 )

property = vtk.vtkVolumeproperty()
property.SetColor(colorFunc)
property.SetScalarOpacity(opacityFunc)
property.SetInterpolationTypetoLinear()

# Set up the Volume
volume  = vtk.vtkVolume()
volume.SetMapper(mapper)
volume.SetProperty(property)

我想将此文件另存为STL文件

stlWriter = vtk.vtkSTLWriter()
stlWriter.SetFileName('stltest')
stlWriter.SetInputConnection(????.GetoutputPort())
stlWriter.Write()

我应该放些什么而不是????作为作家的输入