Accuracy Evaluation of Low-Cost and Professional UAS Orthomosaics for 2D/3D Urban Cadastre Mapping

Resumo

The increasing demand for precise and timely geospatial information, particularly for the evolving three-dimensional urban cadastre, has positioned Unmanned Aircraft Systems (UAS) as essential data acquisition tools. This study compares the positional accuracy of orthomosaics generated by a low-cost UAS (DJI Mini 3) and a professional platform (DJI Matrice 350 RTK + P1) for urban cadastre applications. Two photogrammetric workflows were tested: indirect georeferencing with ground control points for the Mini 3 and direct georeferencing with Network RTK for the Matrice. The 5-ha study area was flown at 70 m altitude, and accuracy was evaluated using the Brazilian Cartographic Accuracy Standard (PEC) at 1:1000 scale. The Matrice achieved a finer ground sampling distance (0.84 cm) and lower positional RMS (4.09 cm) but required longer processing time (4 h 47 m). The Mini 3 produced an RMS of 11.02 cm with shorter processing time (32 min). Despite these differences, both orthomosaics met PEC Class A requirements, demonstrating that low-cost UAS with indirect georeferencing can provide a cost-effective alternative for accurate 2D cadastral mapping.