I think It is slicing an image.
I use imageMapper to get the imageData, then add the imageSlice to the renderer as follow.
const imageMapper = vtkImageMapper.newInstance();
const imageSlice = vtkImageSlice.newInstance();
(The imageData is obtained by using the readImageDICOMFileSeries method of ITK and change them to vtkImageData)
Luckily I get the point through adding this
But I am still confused whether the result is correct and why we need that code.
In addition, during the attempt, I find another question. If I set the setKSlice(30) or other index, the result displayed is different when I import the .dicom files from 0 to 128 with the .dicom files from 0 to 80.