Enhancing UAV-based stockpile volume estimation through geomatics: a case study of salt stockpiles in Hambantota Mahalewaya

Abstract

This research mainly compares three noninvasive survey techniques: Unmanned Aerials Vehicles (UAVs), Differential Global Positioning System (DGPS), and as a conventional survey technique Total Station (TS) in estimating volume measurements of salt stockpiles in an outdoor salt storage facility in Hambantota Mahalewaya, Sri Lanka. Two stockpiles were selected for the study and UAV image data acquired from the different elevations were processed by the ix4dMapper software and by the help of Ground Control Points (GCPs) accurate models were created by georeferencing process. Civil 3D software was utilized to process DGPS and TS data. UAV emerges as an efficient method but for the first stockpile with a higher error percentage which was 5.45% and for the second stockpile was 0.95%. For the first stockpile, the UAV error percentage deviation for DGPS measurement was 0.65% and for the TS it was 2.11%. For the second stockpile, the UAV error percentage deviation for the DGPS measurement was 0.39% and for TS it was 0.85%. Analysis reveals potential error-causing factors in UAV-based estimation, highlighting the significance of underlying topography for improved accuracy. Further attempts need to be taken in improve accuracy, efficiency in stockpile volume estimation by using different geomatic techniques.