Accuracy of automatic tree extraction using airborne laser scanner data

The objective of the EuroSDR/ISPRS Tree Extraction project was to evaluate the quality, accuracy, and feasibility of automatic or semi-automatic tree extraction methods mainly based on high-density laser scanner data. This paper summarizes the major general finding based on laser scanning approaches. Results showed that the tree extraction method is the main factor on the achieved accuracy. When the laser point density increases from two points to eight points per m2, the improvement in crown delineation accuracy was marginal, but in the case of feasible methods the accuracy of the tree location and especially the tree height determination improves, but also deterioration of the accuracy was reported. Individual tree based inventory requires also individual tree based reference collected in the field; this calibration is needed to reduce underestimation of tree height, calibration of the basal area and stem volume and possibly to verify experimentally the quality of the product.