Does voxelPorosity work for polyhedra?

Hi everyone,
  I would like to ask if the voxelPorosity works for specimens composed with polyhedral particles? I have created a cylindrical polyhedral specimen with a radius of 0.15 and a height of 0.9 on the z axis, and then I calculate its porosity using the following command.
  utils.voxelPorosity(resolution=200,start=Vector3(0,0,0),end=Vector3(0.1,0.1,0.5))
  But the output is always 1.
  Is this command valid only for spherical particles? Thank you for your answer!

yours，
xue