Accuracy of unmanned aerial vehicle (UAV) and SfM photogrammetry survey as a function of the number and location of ground control points used
journal contributionposted on 2018-11-15, 11:50 authored by Enoc Sanz-Ablanedo, Jim Chandler, Jose R. Rodriguez-Perez, Celestino Ordonez
The geometrical accuracy of georeferenced digital surfacemodels (DTM) obtained fromimages captured bymicro-UAVs and processed by using structure frommotion (SfM) photogrammetry depends on several factors, including flight design, camera quality, camera calibration, SfM algorithms and georeferencing strategy. This paper focusses on the critical role of the number and location of ground control points (GCP) used during the georeferencing stage. A challenging case study involving an area of 1200+ ha, 100+ GCP and 2500+ photos was used. Three thousand, four hundred and sixty-five different combinations of control points were introduced in the bundle adjustment, whilst the accuracy of the model was evaluated using both control points and independent check points. The analysis demonstrates how much the accuracy improves as the number of GCP points increases, as well as the importance of an even distribution, how much the accuracy is overestimated when it is quantified only using control points rather than independent check points, and how the ground sample distance (GSD) of a project relates to the maximum accuracy that can be achieved.
This work was supported by the University of Leon through Convocatoria de Ayudas para el Fomento de la Publicacion en Acceso Abierto a Profesores de Nueva Incorporacion, 2018 and by Estancias de movilidad en el extranjero “Jose Castillejo” para jovenes doctores (2017), from Ministerio de Educacion, Cultura y Deporte, Gobierno de Espana.
- Architecture, Building and Civil Engineering