Contribution of smartphones for documentation of cultural heritage: A case study of Zilkale

Due to the high complex image scene using only aerial images for 3D documentation of historical sites is challenging. Most existing documentation methods from aerial images still suffer from the abrupt irregular geometric deformations and radiometric changes due to material change, shadows of trees and invisible areas etc. In contrast to displays, it can be said that there are palpable benefits in having high resolution cameras on smartphones. Some benefits of high resolution cameras on smartphones are more detailed captured, sharper images and the more room for digital zooming with less detail loss etc. They may not be perfect that there are perceivable advantages to derive from the higher MP ratings. In this study Zilkale historical sites which is located in the Rize Province was selected as the study area. This study focuses on the 3D documentation of Zilkale, which is a medieval castle consists of outer walls, middle walls and inner castle dated back to 14th and 15th century. In the area 692 high resolution images were taken using by an Unmanned Aerial Vehicle (UAV) and a smartphone as a terrestrial camera. To demonstrate the importance of the terrestrial photographs for documentation wo different 3D models of Zilkale historical monument were produced using the computer vision based photogrammetric software from aerial images and combined of aerial and terrestrial images. Produce models were examined both visually and using some basic metrics for the 3D spatial and image matching accuracy. Study resulted with the success of the combination of terrestrial and aerial images based 3D models especially in the visibility of façades with higher accuracy. Produced models without terrestrial photographs cannot be considered as a reliable product for the 3D documentation of historical monuments or cultural heritage sites.