Documenting historic tileworks using smartphone-based photogrammetry

Photogrammetry is a metric technique for indirect measurement through images. This technique could be applied in recording architectural features and documenting buildings. Therefore, smartphone-based photogrammetry can be considered a creative method for architects and conservators to document monuments quickly and promptly. The main objective of this paper is to study the smartphone-based photogrammetry capabilities in two case studies in terms of accuracy and precision. Historic tileworks in Ḥāfeẓ tomb, Shiraz, Iran, has been considered as examples of traditional decorations in Iranian architecture. For this purpose, close-range photogrammetry with stereo photography was used. A smartphone camera has captured the photos. Photogrammetric steps were performed in Agisoft Metashape Professional. The result was 3D models and an orthoimage of the tiles. The accuracy of the results was acceptable for ordinary documentation and differed on average 0.45% to as-built measures. Orthoimage is believed to be an important document for analyzing and studying the patterns and colors used in these works of art. The results of this study emphasized that close-range photogrammetry with a smartphone can in the future be a public and reliable technique for documenting architectural heritages, especially in medium and small-scale projects.