UAS as an Inventory Tool: A Photogrammetric Approach to Volume Estimation

摘要

Unmanned aircraft systems (UAS), also referred to as unmanned aerial vehicles (UAV) or remotely piloted vehicles (RPV), are associated with unmanned aircraft either controlled by a pilot on the ground or pre-programmed with specific flight paths. Small UASs have seen a massive increase in public interest in recent years as hobbyist platforms; they are, however, a potentially powerful tool in remote sensing and geospatial applications. Due to the increased availability of low-cost UAS, this technology could soon revolutionize many industries, including those that require volumetric estimation. Traditionally volumetric inventories have been performed with tape measurements, and in some instances where accuracy is of utmost importance, survey grade GPS and/or terrestrial light detection and ranging (LiDAR) equipment. UAS platforms can bridge a gap between traditional methods by providing accurate volume estimates quickly and efficiently along with valuable 3D digital data for a historical record. This project addressed this problem using photogrammetric techniques with an inexpensive UAS. Methods of data capture and post processing techniques were explored. Volumetric accuracies were assessed by comparing collected data against in situ reference measurements and engineering diagrams. The results show a promising future for UAS and photogrammetric volume estimation that is both cost and time efficient. Out of thirteen objects surveyed six had a relative error less than 5% and exhibited good quality 3D reconstruction. Of the remaining seven objects, four had a relative error greater than 15% and exhibited a very poor 3D reconstruction. The ability to accurately estimate volume is directly proportional to the quality of the 3D model with the highest quality scenes exhibiting the highest accuracy volume estimates. This project has demonstrated that when suitable circumstances are presented and 3D reconstruction is met with a high level of success, inexpensive UAS and photogrammetry present a powerful tool for performing volume estimation of many objects. Future efforts should include research into the optimization of equipment parameters as well as the effects and limitations of site conditions in order to improve 3D modeling and thus volume estimation.