Estimation of Tree Trunk Diameter by LIDAR while Moving on Foot or by Car

Abstract

    Three dimensional point cloud images of trees were obtained by using LiDAR (Light Detection and Ranging). In this study, light weight portable lidar was used. An operator walks along the target area and the lidar scans point cloud images. Each image is co-registered and a three dimensional image can be constructed. Lidar-derived tree trunk diameter estimation and its directly measured value were compared and the errors were examined when the distance from the target tree was changed. It was shown that the distance from a target tree should be as close as possible. When the distance is more than 80 m, the image generated from the lidar data is too unclear to estimate the tree trunk diameter. Then, walking and cars were adopted as a platform of lidar. Relationship between their moving speed and accuracy of lidar-derived tree trunk diameter estimation was examined. Finally, a site with vegetation was measured by walking and using a car and their obtained images were compared. The advantage of on foot as a platform is high-accuracy and accessibility to uneven grounds. On the other hand, the strong point of a car is less labor working and less time for measurement. Therefore, both walking and using a car are available for the platform of lidar.