Comparative Analysis of GNSS-derived Ground Control Points on UAV Orthomosaic Accuracies; A Case Study of The Federal Polytechnic Ado-Ekiti, Nigeria (Data)

Accurate mapping is essential for a wide range of applications including cadastral mapping, agriculture, environmental monitoring, urban planning, and disaster management. These applications often requires wider area coverage. Leveraging Unmanned Aerial Vehicles (UAVs) for such mapping processes requires image stitching. Ensuring consistent overlap of images during stitching significantly relies on the geometric accuracy of the individual orthomosaics. This study evaluates the consistency of overlapping orthomosaic accuracies when using GNSS Receiver with COR station, GNSS Receivers in Base and Rover differential mode and GNSS Receiver using Global Correction Service (GCS) for observing Ground Control Point (GCP) for UAV image processing. The study area was located within the Federal Polytechnic, Ado-Ekiti, Ekiti State, Nigeria, and UAV data was collected using Mavic Pro Platinum. Observations indicate that locations of GCPs as observed from the aligned images were relatively closer to the GCP locations observed with GNSS using GCS. However, after image processing, results indicate that the Receiver used with CORS and Differential modes provided better accuracy and consistency in 2DRMS, while the GCS Receiver technique exhibits greater discrepancies for orthomosaic overlaps owing to observed low RMS accepted during observation. GNSS + CORS, GNSS used in Base and Rover mode and GNSS + GCS can produce accurate GCP coordinates, and hence, consistent orthomosaics if the methods are correctly used.