Ukrainian Journal of Forest and Wood Science

The issue of improving the accuracy of measuring the height of trees and shrubs is characterized by relevance and practical importance for forestry and landscape gardening due to the influence on the determination of the volume of individual trees and the growing stock. Such measuring is important for landscape and architectural planning and inventory of trees. The purpose of the study was to check the accuracy of measuring the height of trees using a quadrocopter by comparing these results with their true values (measurements of the length of felled trees). In addition, the heights were determined using the Anuchin’s optical hypsometer and a tree caliper. The UAV DJI Phantom 4 was used for measuring the heights. It was originally placed at the root collar of a growing tree to fix the “zero” point and taken off by the operator in 90° shooting mode to the highest point of the tree for calculating the height with GPS-receiver drone instruments. By this way, the information about coordinates and height of the top of the tree as attributes of each photo is stored in digital form. The proposed approach to measuring the height of trees and shrubs using UAV, was developed to create a method that would offset the existing altimeters main disadvantages: the need to mark the base distance, increase the convenience and accuracy of aiming to the top of the tree, eliminate the influence of the terrain and the curvature of the tree on the measurement results and also provide better accuracy of measurements. Checking the accuracy of this measurement process showed relative error of measurement < 1 % and better informational content compared to other methods. The main disadvantages of this method are the complexity of its implementation in conditions of dense stands and high requirement to the qualification of the operator. Such an approach can be used for the forests mensuration needs, for establishing the height classes, inventory of green spaces, creating a database of measurements (with a photographic images of the tops of plants) as well as for other scientific research.

hypsometer, tree height determination method, unmanned aerial vehicle, Phantom 4