What Actually is RMSEz?
RMSE is the root measure square error. It is the difference between the predicted values (LiDAR elevations) and true values (ground truth elevations). It tells us the error in the LiDAR values.
RMSE is always positive and a value of zero reflects a perfect dataset. While this is the ideal situation, it is extremely rare that anything is absolutely perfect. So, the closer the RMSE is to zero, the higher the accuracy of the dataset.