Assessing the performance of a handheld mobile laser scanner to estimate tree height

Measuring and estimating the structural attributes of trees is a fundamental component of forest management and essential for most research in forest sciences. Nowadays, laser scanners (terrestrial and mobile) enable continuous scanning of forested areas, generating point clouds to estimate tree structural attributes. This study evaluated the ability of the GeoSLAM ZEB-REVO handheld mobile laser scanner to estimate tree structural attributes, specifically total height and trunk height. The research was conducted in Karaj Botanical Garden, covering 7.2 hectares with uneven-aged, multi-layered tree stands. Two approaches, i.e. manual and automatic, were applied to the processed point clouds to estimate total and trunk height. For validation, these attributes were measured in the field using a laser range finder. The results showed that the manual and automatic methods estimated total height with RMSE values of 3.17 and 3.21 meters and rRMSE values of 25.48% and 25.80%, respectively. Trunk height estimation yielded RMSE and rRMSE values of 0.47 and 2.56 meters and 12.66% and 69.67% for the manual and automatic methods, respectively. Based on our results, GeoSLAM's ability to estimate total height is weak, while trunk height can be estimated with high accuracy.