Integration of high-precision UAV laser scanning and terrestrial scanning measurements for determining the shape of a water tower

Abstract

This study was aimed at integrating surveys from terrestrial laser scanning (TLS) and high-precision scanning performed by a drone (ULS) for a tower structure. This will allow a complete point cloud to be obtained for the entire object. Integrated measurements will eliminate gaps in the point cloud, characteristic of TLS or ULS separate measurements. Existing studies report ULS accuracy of a few cm, but the precision may be about 10 mm. Assuming that the ULS point cloud will be matched to the TLS cloud, which has higher accuracy, the high accuracy of the whole integrated model can be expected. The integration of the surveys was carried out for the water tower and a coherent model of the structure was obtained, with a mean merge error of 13 mm. Detailed comparative analyses were carried out in selected cross-sections, obtaining mostly a several-millimetre compliance of the results in the analysed categories.