Avaliação da acurácia posicional de produtos aerofotogramétricos gerados com e sem pontos de controle em levantamentos com aeronaves remotamente pilotadas

Abstract

The use of remotely piloted aircraft has become an efficient alternative for acquiring high-resolution geospatial data, particularly for small-and medium-scale surveys. However, the geometric quality of derived products, such as orthophotos and digital surface models, is strongly influenced by the georeferencing strategy adopted, especially the use of ground control points. In this context, this study aimed to evaluate the positional accuracy of aerophotogrammetric products generated under different processing scenarios, comparing the use of ground control points and check points, the use of all points as control, and processing without any ground control points, including the assessment of the effect of altimetric transformation using a geoid model. The survey was conducted at the external area of the Rectory Campus of the Federal Institute of Education, Science and Technology of Piauí (IFPI), in Teresina, Piauí, Brazil, covering an area of 41,935.4 m², using a remotely piloted aircraft equipped with an onboard GNSS receiver, and image processing was performed using commercial photogrammetric software. Positional accuracy assessment was based on the root mean square error (RMSE) for horizontal, vertical, and three-dimensional components. The results showed that scenarios using ground control points achieved centimeter-level horizontal accuracy and better three-dimensional performance. In contrast, scenarios without ground control points exhibited a significant reduction in accuracy, particularly in the vertical component, although altimetric transformation provided substantial improvements. The findings indicate that the choice of geodetic control strategy should be guided by the intended application of the products, balancing accuracy requirements, fieldwork time, processing effort, and operational costs. Keywords: aerophotogrammetry; ground control points; positional accuracy; unmanned aerial vehicles; georeferencing.