LiDAR rotation initialization failed (hand-eye calibration)

[vkorotkine]

Describe the bug
The terminal output is as follows

initialize rotation 'SO3_LkToBr' failed, this may be related to the 'NDTResolution' of lidar odometer.

My understanding is that this means the output of the hand-eye initialization step for the LiDAR rotations (Eq 31 the arXiv version of your paper) is badly conditioned, as it is thrown by _solveFlag not being set to true, which is in turn set by the following

    if (cov(2) > 0.25) {
        
        // get result
        Eigen::Matrix<double, 4, 1> x = svd.matrixV().col(3);
        Eigen::Quaterniond quat(x);
        Sophus::SO3d splineToSensor(quat);

        _solveFlag = true;
        _sensorToSpline = splineToSensor.inverse();
    }

Do you have any insight as to why this happens/ when you had this problem?
This is from an outdoor dataset. Would this be solved by using a different LiDAR odometry pipeline?
Thank you,
Vassili