new_contents: #!/usr/bin/env python
  # coding: utf-8
  import numpy as np
  import numpy.linalg as LA
  from MotionEST import MotionEST
  """Ground Truth:
  
      Load in ground truth motion field and mask
  """
  
  
  class GroundTruth(MotionEST):
    """
      constructor:
          cur_f: current frame
          ref_f: reference frame
          blk_sz: block size
          gt_path: ground truth motion field file path
      """
  
    def __init__(self, cur_f, ref_f, blk_sz, gt_path):
      self.name = 'ground truth'
      super(GroundTruth, self).__init__(cur_f, ref_f, blk_sz)
      self.mask = np.zeros((self.num_row, self.num_col), dtype=np.bool)
      with open(gt_path) as gt_file:
        lines = gt_file.readlines()
        for i in xrange(len(lines)):
          info = lines[i].split(';')
          for j in xrange(len(info)):
            x, y = info[j].split(',')
            #-,- stands for nothing
            if x == '-' or y == '-':
              self.mask[i, -j - 1] = True
              continue
            #the order of original file is flipped on the x axis
            self.mf[i, -j - 1] = np.array([float(y), -float(x)], dtype=np.int)
  
subject: Add Ground Truth Estimator