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

From: 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

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 \( \frac{n_{1\overset{\sim }{x}}}{N_1} \)
  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