ESTIMATING INDIVIDUAL TREE HEIGHTS AND DBHS FROM VERTICALLY DISPLACED SPHERICAL IMAGE PAIRS

摘要

Individual tree parameters, such as diameter at breast height (DBH) and tree height, are fundamental measurements in forest inventory, and often labour intensive and require significant financial expenditures. Applying digital imaging in forest inventory is an efficient way to decrease the workload. In this study, spherical images taken using a novel commercial 360° camera (Ricoh Theta S) and stereographic geometry were applied to obtain these parameters directly without stitching multiple images from common cameras. This technology was validated in both a sparse urban forest (pairwise comparison) and denser real forest (distributional comparison) in Atlantic Canada. The DBH (r2 0.76) and height (Dmax 0.25, K-S test) showed high correspondence with field measures. The spherical camera represents a low-cost option to terrestrial laser scanning and has potential to produce more accurate forest-level estimates with quicker field and office processing time than current under-canopy remote sensing technologies.