On January 29, 2022, researchers at the Lyles School of Civil Engineering, Purdue University, West Lafayette, IN, published a paper titled “A Comparative Analysis of Multi-Platform, Multi-Resolution, Multi-Temporal LiDAR Data for Forest Inventory” in the Journal Remote Sensing (14, 649).
This study investigated multi‐platform/resolution/temporal LiDAR data over a forest plantation to determine the point cloud quality and captured level of information for deriving different forest inventory metrics. The paper did not compare accuracies between the LiDAR platforms, but rather the ability to consistently capture forestry metrics.
The main findings are as follows:
- The Geiger-mode LiDAR provides denser point clouds while operating at a higher altitude. In this study, the median of the planimetric point density for Geiger-mode and linear LiDAR datasets is 248 ppsm and 4 ppsm, respectively. The flying height of the Geiger-mode and linear LiDAR systems is approximately 3700 m and 2000 m above ground, respectively.
- The Geiger-mode LiDAR captures a much higher level of information as compared to linear LiDAR. In fact, the level of information obtained by the Geiger-mode LiDAR is found to be close to that captured by the UAV LiDAR.
- Both the Geiger-mode and linear LiDAR effectively characterize the terrain in the study site. The Geiger-mode LiDAR is able to deliver forest attributes including individual tree counts, tree locations, and tree heights with accuracy comparable to those from the UAV LiDAR. The linear LiDAR, on the other hand, fails to capture individual trees, and it is unclear from this study whether it can reliably derive canopy height
In addition, the results show the following:
- Canopy cover percentage has a critical impact on the ability of aerial and terrestrial systems to acquire information corresponding to the lower and upper portions of the tree canopy.
- All the systems can obtain adequate ground points for digital terrain model generation irrespective of canopy cover conditions.
- Point clouds from different systems are in agreement within a ±3 cm and ±7 cm range along the vertical and planimetric directions, respectively.
Scanning patterns of (a) linear LiDAR and (b) Palmer scanner for the VeriDaaS Geiger-mode LiDAR System.
The paper also notes that, the Geiger-mode system’s “use of a Palmer scanner, together with a 15-degree scan angle of the laser and scan pattern of a 50% swath overlap, enables multi-view data collection, which aids in minimizing occlusions and shadowing.”
Download full journal article here
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