Canopy densities were then computed as the proportion of echoes above each layer to total number of first echoes and labeled TF0 (>1.3 m), TF1,…, TF9.
Maltamo et al. (2011) used the LiDAR metrics VEG (the proportion of ground echoes vs canopy echoes using a threshold value of 2 m) and H90 (plot level 90 percentile for height based on first returns) as a basis for plot selection.
Canopy densities were then computed as the proportion of ALS echoes above each fraction to total number of first echoes and labeled D0.F (>2 m), D1.F, …, D9.F.
The subscript indicates which descriptive statistic or percentile value was used and whether it was applied to a proportion of the echoes (sd = standard deviation, first = first-of-many echoes) Table 5 The SUR model for the plot volume based on the Sp75+95 strategy to stratify the dominant species.
= Canopy densities corresponding to the proportion of last echoes above fraction #0 (2 m), #1 and #2 (see text).
Importantly, our cohort compares favorably with other clinical cohorts in critical care in terms of the proportion of interpretable echoes [20, 46, 60].
However, it should be noted that the number of the larger plots was relatively small.> -wrap-foot> aD1F.and1F.and D3.F = Canopy densities corresponding to the proportion of first echoes above fraction #0 (2 m), #1 and #3 (see text).
The I, D, and H refer to intensity, density, and height metrics; Vegeratio is the ratio of echoes above 2 m height to all echoes; and Prop_first is the proportion of first echoes to all echoes.
The features describing the proportion of the first echoes and the intensity recordings of the echoes were among the best features for the species discrimination.
The other ALS features considered were the mean and standard deviation of the intensity values and the proportion of the different echoes (Vauhkonen et al. 2014b).
