train_val.py 文件源码

def filter_roidb(roidb):
  """Remove roidb entries that have no usable RoIs."""

  def is_valid(entry):
    # Valid images have:
    #   (1) At least one foreground RoI OR
    #   (2) At least one background RoI
    overlaps = entry['max_overlaps']
    # find boxes with sufficient overlap
    fg_inds = np.where(overlaps >= cfg.TRAIN.FG_THRESH)[0]
    # Select background RoIs as those within [BG_THRESH_LO, BG_THRESH_HI)
    bg_inds = np.where((overlaps < cfg.TRAIN.BG_THRESH_HI) &
                       (overlaps >= cfg.TRAIN.BG_THRESH_LO))[0]
    # image is only valid if such boxes exist
    valid = len(fg_inds) > 0 or len(bg_inds) > 0
    return valid

  num = len(roidb)
  filtered_roidb = [entry for entry in roidb if is_valid(entry)]
  num_after = len(filtered_roidb)
  print('Filtered {} roidb entries: {} -> {}'.format(num - num_after,
                                                     num, num_after))
  return filtered_roidb