Effects of Density of Ground Control Points On the Accuracy of Orthophotos Produced Using UAV
Abstract
Ground control points are needed in the production process of any accurate photogrammetric output. They are used to georeference the acquired images. The aim of this research is to investigate the effects of density and distribution of ground control points on the accuracy of orthophotos produced by UAVs. To achieve this, an area of 15.2 hectares was photographed with DJI Marvic Air UAV. One hundred and eighty (180) images were captured at an altitude of 60m above the ground. Ground control points (GCPs) and check points (CPs) were established using Hi-Target GNSS with external antenna. The images acquired were processed using Pix4Dmapper photogrammetric software. Bundle adjustment was performed with the number of GCPs increased from eight (8) to nineteen (19). The orthophoto generated were analyzed by comparing the ground coordinates with orthomosaic coordinates. Root mean square error (RMSE) analysis was conducted, one for each of the configuration of GCPs. The smaller the RMSE value, the higher the accuracy of the orthophoto. The configuration with 19 GCPs produced the best result with RMSE of 1.2195 m, ±0.8461 m and ±0.0129 m for easting, northing and height respectively. It can be concluded that the density and distribution of the GCPs have an effect on the production and accuracy of orthophotos. Difference in accuracy in respects to GSD’s should be tested out to obtain the optimal GSD for mapping and number of GCP’s for study area consists of differential elevation profile.
Keywords
Unmanned Aerial Vehicle; Agisoft Photoscan; Digital Elevation Model; Orthophoto
Citations
IRE Journals:
Bello Isah Kontagora, Muhammad Bala, Jiya Jacob "Effects of Density of Ground Control Points On the Accuracy of Orthophotos Produced Using UAV" Iconic Research And Engineering Journals Volume 9 Issue 6 2025 Page 1118-1126 https://doi.org/10.64388/IREV9I6-1712735
IEEE:
Bello Isah Kontagora, Muhammad Bala, Jiya Jacob
"Effects of Density of Ground Control Points On the Accuracy of Orthophotos Produced Using UAV" Iconic Research And Engineering Journals, 9(6) https://doi.org/10.64388/IREV9I6-1712735
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