def add_true_negatives(err, cnt_gt):
    """Update errors statistics of a specific method with missing detections"""
    matched = len(err['all'])
    missed = cnt_gt - matched
    zeros = [0] * missed
    err['<0.5m'].extend(zeros)
    err['<1m'].extend(zeros)
    err['<2m'].extend(zeros)
    err['matched'] = 100 * matched / cnt_gt
