def _get_normalize_factor(self, gt_coords: np.ndarray) -> np.ndarray:
        """Get the normalize factor. generally inter-ocular distance measured
        as the Euclidean distance between the outer corners of the eyes is
        used.

        Args:
            gt_coords (np.ndarray[N, K, 2]): Groundtruth keypoint coordinates.

        Returns:
            np.ndarray[N, 2]: normalized factor
        """
        idx1, idx2 = self.keypoint_indices

        interocular = np.linalg.norm(
            gt_coords[:, idx1, :] - gt_coords[:, idx2, :],
            axis=1,
            keepdims=True)

        return np.tile(interocular, [1, 2])
Get the normalize factor. generally inter-ocular distance measured
        as the Euclidean distance between the outer corners of the eyes is
        used.

        Args:
            gt_coords (np.ndarray[N, K, 2]): Groundtruth keypoint coordinates.

        Returns:
            np.ndarray[N, 2]: normalized factor
        
mmpose/mmpose/evaluation/metrics/keypoint_2d_metrics.py