Table 2. Abbreviations and descriptions of 26 vertical metrics.

Abbreviations	Metrics	Description
m	mean	The mean height of all points
p.n.	percentile[n](n = 1, 10, 20, 30, 40, 50, 60, 70, 80, 90, 99)	Height at which n% of points is located
kur	kurtosis	The kurtosis of the heights of all points
sk	skewness	Symmetry of heights of all points
sd	standard_deviation	The standard deviation of heights of all points
d.n.	density[n](n = 1,2,3,4,5,6,7,8,9,10)	With the point cloud data divided into ten layers with the equal height interval, these metrics indicate point density of the nth layer from the bottom.
aad	average_absolute_deviation	Average absolute deviation between the height of each point and average height of all points