A Comparison of Linear-Mode and Single-Photon Airborne LiDAR in Species-Specific Forest Inventories

Abstract

Single-photon airborne light detection and ranging (LiDAR) systems provide high-density data from high flight altitudes. We compared single-photon and linear-mode airborne LiDAR for the prediction of species-specific volumes in boreal coniferous-dominated forests. The LiDAR data sets were acquired at different flight altitudes using Leica SPL100 (single-photon, 17 points • m −2 ), Riegl VQ-1560i (linear-mode, 11 points • m −2 ), and Leica ALS60 (linear-mode, 0.6 points • m −2 ) LiDAR systems. Volumes were predicted at the plot-level using Gaussian process regression with predictor variables extracted from the LiDAR data sets and aerial images. Our findings showed that the Leica SPL100 produced a greater mean root-meansquared error (RMSE) value (41.7 m 3 • ha −1 ) than the Leica ALS60 (39.3 m 3 • ha −1 ) in the prediction of species-specific volumes. Correspondingly, the Riegl VQ-1560i (mean RMSE = 33.0 m 3 • ha −1 ) outperformed both the Leica ALS60 and the Leica SPL100. We found that the cumulative distributions of the first echo heights > 1.3 m were rather similar among the data sets, whereas the last echo distributions showed larger differences. We conclude that the Leica SPL100 data set is suitable for area-based LiDAR inventory by tree species although the prediction errors are greater than with data obtained using the modern linear-mode LiDAR, such as Riegl VQ-1560i. Index Terms-Airborne laser scanning, Gaussian processes (GPs), light detection and ranging (LiDAR) intensity, photon-counting LiDAR. I. INTRODUCTION A IRBORNE light detection and ranging (LiDAR) has established its role in forest inventories [1]-[3]. LiDAR systems have developed rapidly during the last decade, and the development has mainly focused on linear-mode LiDAR systems. These conventional linear-mode LiDAR systems can operate in discrete return or full-waveform modes. Discrete return LiDARs record distinct echoes, whereas full-waveform systems can store the continuous shape of both the outgoing Manuscript

Detection of standing retention trees in boreal forests with airborne laser scanning point clouds and multispectral imagery

“…These sources include conventional linear-mode airborne LiDAR data with a higher pulse density from any airborne platform and even single-photon LiDAR data (e.g. Räty et al, 2022). Balancing efficiency and cost are of the essence, however, especially if we consider application of our findings to large areas and other parts of the world, hence why we decided to employ nationwide data with a lower pulse density.…”

Utilizing Single Photon Laser Scanning Data for Estimating Individual Tree Attributes

“…The SPL system has been used in a few studies internationally, and few in Finland. The earlier studies have documented that SPL can be a promising technology for forestry applications (White et al, 2021) (Raty et al, 2021), (Yu et al, 2020); (Wästlund et al, 2018). For example, Wästlund et al, (2018) studied SPL with area-basedapproach (ABA) method in a hemi-boreal forest area of 1300 ha where forest management is active.…”