Accuracy assessment of different photogrammetric software for processing data from low-cost UAV platforms in forest conditions

To obtain precise cartometric measurements of forests is always a challenge and high-resolution data from Unmanned Aerial Vehicle (UAV) is currently the quickest method. Generation of a fine quality orthomosaic of the acquired image series is a pre-requisite for full exploitation of such data. This study examines six of the most frequently used photogrammetric software for popular and inexpensive UAV systems. It is assumed that ground control points (GCPs) are not required. The average Root Mean Square Error (RMSE) for raw orthophoto was 1.24 m and around 0.2 m precision for both X and Y axes. Additionally, the accuracy of UAV internal GNSS receiver was checked on reference points which slightly exceeds 2 m RMSE. The range of accuracy and precision of orthomosaic are provided as a valuable reference for the use of low-cost UAV in forest inventory.