Statistical assessment of cartographic product from photogrammetry and fixed-wing UAV acquisition

Abstract

Geometric accuracy is an important attribute of cartographic products and UAV photogrammetry has been gaining market in topographic mapping thanks to high spatial and temporal resolution, however, they need proper evaluation following accuracy standards and protocols. Regarding this, this work evaluates products from digital photogrammetry from images acquired with a fixed-wing UAV (18Mpixel camera) in a 300-380m height flight over a Hydroelectric Power Plant (HPP) in Brazil. A dataset of 23 ground control points assessed with an RTK-GNSS (using natural targets) was validated with its homologous in the Digital Surface Model (DSM) and the orthomosaic, following a workflow in which the appropriate statistics were applied. Following parametric tests like the Students t-test and the Chi-square, we compared the results with the Brazilian Cartographic Standard for digital cartography, achieving minimum scale of 1: 20,000 (RMSE of 1.04 m) for the orthomosaic, and minimum scale of 1: 10,000 (RMSE of 1.31 m) for the elevation in the DSM, although, no special targets were used. As the 3D mapping generated using the photogrammetry still needs a protocol to evaluate the accuracy, this work applied a proposed workflow respecting the quality of the data to meet the requirements of the cartographic standard.

Enrichment of Uav Photogrammetric Point Cloud to Enhance DSM in a Dense Urban Region

“…For example, parameters tests like the chi-square test and student t-test can be used to evaluate the accuracy of ground control points obtained from UAV and topographic survey for DSM and orthophoto generated (Marques Junior et al, 2020). A research framework was presented to evaluate photogrammetric point cloud and DSM based on automatically extracted sample patches.…”