Abstract
Diameter at breast height (DBH) is one of the most important parameter in forestry. With increasing use of terrestrial and airborne laser scanning in forestry, new exceeding possibilities to directly derive DBH emerge. In particular, high resolution point clouds from laser scanners on board unmanned aerial systems (UAS) are becoming available over forest areas. In this case study, DBH estimation from a UAS point cloud based on modeling the relevant part of the tree stem with a cylinder, is analyzed with respect to accuracy and completeness. As reference, manually measured DBHs and DBHs from terrestrial laser scanning point clouds are used for comparison. We demonstrate that accuracy and completeness of the cylinder fit are depending on the stem diameter. Stems with DBH > 20 cm feature almost 100% successful reconstruction with relative differences to the reference DBH of 9% (DBH 20–30 cm) down to 1.8% for DBH > 40 cm.
Highlights
Introduction and MotivationThe distribution of tree diameter, measured at the breast height 1.3 m, is a fundamental parameter for characterization forest stands, including economic as well as ecologic aspects [1,2,3,4]
The precision measure describes how well the LiDAR points fit to the estimated stem cylinder
This results in a 76.6% success rate for the cylinder fit itself
Summary
The distribution of tree diameter, measured at the breast height 1.3 m, is a fundamental parameter for characterization forest stands, including economic as well as ecologic aspects [1,2,3,4]. Terrestrial laser scanning, from tripods or mobile platforms [6] was suggested to automatically measure tree height and DBH, but this is again restricted to plots and hampered by accessibility. Still, those methods are operational and achieve accuracy in sub-dm level for DBH
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