Influence of Lidar Full-Waveform Density and Voxel Size on Forest Stand Estimates

摘要

The aim of this study was to analyze the variation on accuracy and errors of aboveground biomass (AGB) and canopy base height (CBH) estimates when modifying lidar full-waveform (FW) pulse density, voxel size and regression methods. We reduced randomly pulse density from 9 to 1 pulses.m^{-2 in steps of 0.5 pulses.m-2 in 36 plots. Afterwards, eight FW metrics were computed for each pulse density, voxel size (i.e. 0.25, 0.5 and 1 m) and plot. These metrics were used as explanatory variables, while AGB and CBH obtained from field work were used as response variables in linear, square-root-transformed, exponential and power regression models. Results on CBH showed that power regression reduces pulse density influence. AGB was however influenced by voxel size, showing that it was more affected by pulse density changes when using smaller voxel sizes. In addition, square-root-transformed and power regressions performed better for AGB and CBH, respectively.}