Effects of Flight Plan Parameters on the Quality and Usability of Low-Cost UAS Photogrammetry Data Products for Tree Crown Delineation

The continued understanding of the influence of flight planning characteristics on data quality is crucial in the demand for minimizing costs and maximizing the output potential of Uncrewed Aerial Systems (UAS) for forestry applications. This study was conducted to ascertain the effects of various combinations of flying height and percentage overlaps on the quality of photogrammetry data products generated from images acquired by a low-cost UAS (Mavic 2 Pro), with emphasis on tree crown delineation in a Mangium plantation forest in the Philippines. The quality of the products is evaluated based on their completeness and the accuracy of tree crown delineations. Results suggest that the percentage completeness increases as the flying height and percentage overlap increase. More than 90% completeness was achieved for 90% overlap regardless of the flying height. Tree crown delineations using multiresolution segmentation of Digital Surface Models (DSMs) generated from images with a flying height of 120 m and percentage overlap of 80% and 90%, achieved the highest overall accuracy of 43.35%. This study showed that a minimum of 80% overlap must be aimed when acquiring images to ensure higher completeness of the data products and that flying at 120 m above ground with at least 80% overlaps can provide more accurate tree crown delineations.