*3.3. Features' Importance*

The results of evaluation the importance values of features indicated that all of the features have affected the positioning accuracy of u-blox ZED-F9P. The top influential feature was tree height. Then, the influential features were ranked by their importance to the tree height feature. The ground elevation and aspect have gained 79% and 62% importance of the tree height, respectively. The importance of the other features has steadily decreased from the canopy surface elevation to the surface aspect. Two out of five top influential features were classified in the category of tree characteristics (Figure 6).
