Geospatial technologies in 3D documentation and promotion of cultural heritage - example of Fortica fortress on the island of Pag

The development of geospatial technologies (GST) has accelerated the process of 3D documentation and facilitated the promotion of cultural heritage. In this paper 3D documentation and promotion of Fortica fortress (Pag island, Republic of Croatia) has been made. The methods of close-range photogrammetry (CRP), 3D print and modern visualisation technique (virtual reality) were used. Data was collected using UAV Phantom 4 Pro, DSLR Nikon D5300 and GNSS RTK Stonex X10. High-resolution 3D models of Fortica were generated using Agisoft Metashape 1.5.1. The dense cloud of the Fortica with 33 million points was generated. Digital surface model (DSM) with spatial resolution of 1,3 cm and digital orthophoto with spatial resolution of 0,6 cm, were created from dense point cloud. The total RMSE of control points was 4,04 cm in the reference coordinate system and 0,24 pixels in the imaging coordinate system. 3D model of the Fortica fortress was used to create virtual walks, while Prusa i3 mk3 physical model of the Fortica fortress was created with the 3D printer. Virtual walk was displayed in the Samsung GearVR model. The proposed methodological framework provides cultural heritage experts with an easy and cost-effective way of generating relatively accurate 3D models and applying these models to various promotional and educational purposes.