Abstract:
Technologically advanced tools such as Unmanned Aerial Systems (UAS) permit users to collect up-to-date high quality imagery of cultural and historical monuments. Experts have explored the use of UAS for creating 3D models of individual historical monuments or complexes of buildings and facilities. In order to demonstrate the suitability, reliability and precision of the technology, this paper describes approach used to acquire aerial images with DJI INSPIRE-1 quadcopter to create image mosaics, 3D point clouds and 3D image models. The selected case study is the memorial complex – the monument of Okolchitsa peak in the “Vrachanski Balkan” Nature Park, which is consisting of a high vertical object – opulent cross with a height of 26,60m and a building of the Chapel of St. George. The approach of stairs to the monument, as well as the surrounding area, is also included in the tested area. The output results are obtained by applying a Structure from motion (SfM) method using Pix4Dmapper software package for digital image processing and 3D modeling. The deliverables include the following digital products: orthophoto mosaic, digital surface model (DSM), digital terrain model (DTM), 3D model and 3D visualization of the historical monument. Our results demonstrate applicability of low-cost UAS to obtain digital data of sufficient quality to meet photogrammetric standards by acquiring of multiview imagery suitable for SfM processing and the creation of 3D models of adequate geometric accuracy for the management and monitoring of cultural and historical heritage sites.