diff --git a/src/estimate_covariance/estimate_covariance.cpp b/src/estimate_covariance/estimate_covariance.cpp
index 4e71bb0a..8063530e 100644
--- a/src/estimate_covariance/estimate_covariance.cpp
+++ b/src/estimate_covariance/estimate_covariance.cpp
@@ -91,9 +91,14 @@ std::vector<Eigen::Matrix4f> propose_poses_to_search(const NdtResult& ndt_result
   assert(offset_x.size() == offset_y.size());
   const Eigen::Matrix<double, 6, 6>& hessian = ndt_result.hessian;
   const Eigen::Matrix4f& center_pose = ndt_result.pose;
-  const Eigen::Matrix2d covariance = estimate_xy_covariance_by_Laplace_approximation(hessian);
-  // const Eigen::Matrix2d rot = find_rotation_matrix_aligning_covariance_to_principal_axes(-covariance);
+
+  // (1) calculate rot by pose (default)
   const Eigen::Matrix2d rot = ndt_result.pose.topLeftCorner<2, 2>().cast<double>();
+
+  // (2) calculate rot by covariance (alternative)
+  // const Eigen::Matrix2d covariance = estimate_xy_covariance_by_Laplace_approximation(hessian);
+  // const Eigen::Matrix2d rot = find_rotation_matrix_aligning_covariance_to_principal_axes(-covariance);
+
   std::vector<Eigen::Matrix4f> poses_to_search;
   for(int i = 0; i < static_cast<int>(offset_x.size()); i++) {
     const Eigen::Vector2d pose_offset(offset_x[i], offset_y[i]);