Delineation of homogeneous forest patches using combination of field measurements and LiDAR point clouds as a reliable reference for evaluation of low resolution global satellite data

Forest Ecosystems

Table 1 The structural variables (SVs) extracted from ALS point clouds used to identify homogeneous patches

No.	Symbol	SVs	Description	Equation
1	p95	height	95th height percentile of all returns	\( {x}_0+\frac{h_0}{n_0}\left(\frac{p_{95}-N}{100}-{F}_{-1}\right) \)
2	pFRAMe	density	ratio: number of first returns above median height to the total number of first returns	\( \frac{n_{1\overset{\sim }{x}}}{N_1} \)

x height of the return; x₀ lower bound of given percentile; h₀ range of the class interval of given percentile; n₀ frequency of the interval of given percentile; N total number of all ALS returns; F₋₁ cumulative frequency of the interval preceding given percentile; \( {n}_{1\overset{\sim }{x}} \) number of first ALS returns above the values determined by median of all returns; N₁ number of first ALS returns