Assessment of photogrammetric mapping accuracy based on variation ground control points number using unmanned aerial vehicle

• Published in: Measurement : journal of the International Measurement Confederation 2017-02, Vol.98, p.221-227
• Main Authors: Agüera-Vega, Francisco, Carvajal-Ramírez, Fernando, Martínez-Carricondo, Patricio
• Format: Article
• Language: English
• Subjects: Accuracy; Accuracy evaluation; Error analysis; Georeferencing; Ground based control; Ground level; Ground stations; Model accuracy; Orthophoto; Photogrammetry; Root-mean-square errors; Standard deviation; Temporal resolution; UAV; Unmanned aerial vehicles
• ISSN: 0263-2241; 1873-412X
• DOI: 10.1016/j.measurement.2016.12.002

•Ground Control Points number influence on the accuracy of UAV photogrammetric product.•15 Ground Control Points yielded optimal horizontal and vertical accuracy.•Maps at 1:150 scale and contour interval of 15cm are reached from UAV-photogrammetry. Digital Surface Models and orthoimages at high spatial and temporal resolution and accuracy is of increasing importance for many applications. From several years ago photogrammetry-UAV is being used to produce these topographic products. The aim of this study is to analyse the influence of the number of Ground Control Points used for georeferencing on Digital Surface Model and orthoimage accuracies obtained with UAV-photogrammetry. In this purpose, 160 images were taken on a 17.64ha surface at 120m altitude above ground level, and five replications of photogrammetric projects taking into account 4, 5, 6, 7, 8, 9, 10, 15, and 20 GCPs were made. Root Mean Square Error (RMSE) was used as accuracy measurement. Optimal results for RMSEX, RMSEY and RMSEXY mean±standard deviation values were reached for 15 GCPs: 3.3±0.346, 3.2±0.441, 4.6±0.340 and 4.5±0.169cm respectively. Similar conclusions was derived for vertical accuracy: lower RMSEZ mean±standard deviation values were reached for 15 and 20 GCPs: 5.8±1.21cm and 4.7±0.860cm respectively. In view of these results maps at 1:150 scale and contour interval of 15cm can be obtained from UAV-photogrammetry.