code: def _get_pos_units(pos):
      """Get the units of a point cloud.
  
      Determines the units a point cloud of sensor positions, provides the
      scale factor required to ensure the units can be converted to meters.
      """
      # get rid of None elements
      nppos = np.empty((0, 3))
      for ii in range(0, len(pos)):
          if pos[ii] is not None and sum(np.isnan(pos[ii])) == 0:
              nppos = np.vstack((nppos, pos[ii]))
  
      idrange = np.empty(shape=(0, 3))
      for ii in range(0, 3):
          q90, q10 = np.percentile(nppos[:, ii], [90, 10])
          idrange = np.append(idrange, q90 - q10)
  
      size = np.linalg.norm(idrange)
  
      unit, sf = _size2units(size)
  
      return unit, sf
  
imports: from copy import deepcopy
  import numpy
  from ...utils import logger
label_desc: Use image node_id 3 for calling a global function with example usage: _get_pos_units(pos) and returns: unit,  sf