Comparison of accuracy of tree height and position focusing on differences in position determination method in UAV measurement

We performed comparative verification of accuracy of dense cloud produced by UAV aerophotos to reveal the effect of the difference of absolute orientation methods. The methods of orientation are, (1) coordinates of GCP and platform GNSS are taken into aero-triangulation, (2) coordinates of GCP and platform GNSS are used for rigid transformation of dense cloud that was produced first. And in each methods, we produced dense clouds in two ways : whether to use GCP or not. Verification of accuracy was done by comparing of tree locations obtained from LiDAR data and each dense clouds. The result of horizontal accuracy of method (2) was significantly inferior to method (1). After projective transformation by using picked-up tree coordinates, horizontal accuracy of method (2) was greately improved. In terms of height accuracy, the error is under 10% of tree height in method (1) with GCP. But in method (1) with no GCP, overall deviation occurred. In method (2), affect of non-linear distortion of the dense cloud was suggested.