Effects of terrestrial LiDAR scanning parameters and point cloud simplification on forest tree parameter extraction

Forest parameters are the basic indicators for estimating forest volume and forest biomass, and the traditional manual survey method is time-consuming and laborious, and it is difficult to adapt to the requirements of digital forest resources monitoring technology under the new situation. Terrestrial LiDAR scanning technology can obtain small-scale and high-resolution internal structure information of forest stands, which provides a new idea for extracting diameter at breast height and tree height under stand environmental conditions. The existing terrestrial LiDAR scanning studies mostly focus on the extraction methods of forest parameters, but pay less attention to the combination of scanning resolution and quality, and the simplification of laser point clouds.

Taking the Chinese fir forest of Lutou Experimental Forest Farm as the research object, this paper designed seven different scanning combinations for the FARO Focus 3D X330 3D laser scanner to scan the sample plot, and proposed the idea of quadrant corner point cloud simplification for parameter extraction and accuracy evaluation, and then explored the influence of different scanning combinations on the accuracy and efficiency of forest diameter at breast height and tree height parameter extraction.

1) When the resolution was 1/2 and the quality was 4X, the accuracy of the diameter at breast height parameter extraction was the highest; and when the resolution was 1/4 and the quality was 4X, the extraction accuracy of tree height parameters was the highest. 2) Under the condition that there was no significant difference in forest extraction parameters, the scanning parameters with a quality of 4X work the most efficiently when the resolution was 1/4. 3) Select scan results with a resolution of 1/4 and a quality of 4X, which took accuracy and efficiency into account, and simplified the quadrant corner point cloud. The simplified point cloud accurately extracted the parameters of the diameter at breast height.

The results of this study have important reference value for the selection of scanning parameters and point cloud simplification methods for forest land with the same or similar geographical conditions and tree species, which can improve the efficiency of the data processing, and also provide a method and technical reference for the field sample survey by terrestrial LiDAR.