Height estimation of pine (Pinus eldarica) single trees using slope corrected shadow length on unmanned aerial vehicle (UAV) imagery in a plantation forest
DOI:
https://doi.org/10.15287/afr.2023.3014Abstract
Tree height is one of the key parameters in forest plantations that plays a crucial role in estimation of above-ground biomass (AGB) of trees and stands. The parameter may be obtained by different methods from airborne remotely sensed datasets such shadow length of each tree individual or crown height models (CHMs). However, tree height estimation based on shadow length might be biased considering diverse topography of forest sites. Therefore, this study aims to develop a reliable method to estimate tree height in a plantation forest using shadow length on UAV imagery. First, heights of 151 pine (Pinus eldarica) trees were precisely measured in Pardisan Park, North Khorasan province, Iran. Additionally, a collection of images was captured by a Phantom 4Pro UAV in order to illustrate the study area. Then, two different approaches were considered to estimate the height of trees. In the first approach, tree heights were estimated based on shadow length on the UAV orthomosaic and correcting the effect of slope. The second approach considered the UAV-based CHM and height estimation using CHM segmentation and local maximum filtering. The results showed that tree heights estimated by the first approach were not significantly different from the in-situ data (p=0.298). Furthermore, the heights estimated by the slope corrected shadow length showed higher precision compared to the heights estimated by the shadow length without slope correction (Relative root mean squared error, RRMSE 5.6% and 8.2% respectively). However, the heights obtained from the first approach were less precise than the second approach (RRMSE 5.6% and 4.2% respectively). In general, it was concluded that height estimation of pine trees based on shadow length after correction of slope effects can be considered as a reliable approach, although CHM is more efficient in estimating the tree heights. The findings of this study are applicable for height estimation of pine trees within plantation forests on UAV imagery.Downloads
Published
Issue
Section
License
All the papers published in Annals of Forest Research are available under an open access policy (Gratis Gold Open Access Licence), which guaranty the free (of taxes) and unlimited access, for anyone, to entire content of the all published articles. The users are free to “read, copy, distribute, print, search or refers to the full text of these articles”, as long they mention the source.
The other materials (texts, images, graphical elements presented on the Website) are protected by copyright.
The journal exerts a permanent quality check, based on an established protocol for publishing the manuscripts. The potential article to be published are evaluated (peer-review) by members of the Editorial Board or other collaborators with competences on the paper topics. The publishing of manuscript is free of charge, all the costs being supported by Forest Research and Management Institute.
More details about Open Access:
Wikipedia: http://en.wikipedia.org/wiki/Open_access