Layers of Past and Future, Geomatics applied to Archaeological Sites, a case study: Hierapolis of Phrygia, Turkey

My thesis will focus on the role of Geomatics in supporting the analysis and documentation of archaeological sites with geomatics technologies. More specifically, assessing the possibility to extract and investigate additional valuable information based on multi-temporal imagery acquired by UAVs (Unmanned Aerial Vehicles) with visible and NIR (Near-Infrared) sensors. The case study selected for the investigations is Hierapolis of Phrygia, Turkey. The main issues discussed in the work are the evaluation of positional and thematic accuracy of the generated data, the impact of extracting relevant information from NIR and DSM (Digital Surface Model) data, the assessment of the performance of the different software involved in the various processes and the creation of a GIS of the area of interest. The main objective of this thesis is to suggest different geomatics methods and technologies for analysing and monitoring archaeological sites. Additionally, it attempts to demonstrate which of the methods might contribute to- and support the documentation of these sites as well as urban areas in general. The focus is on the needs of archaeologists, along with the idea that these technologies could be reinforced and more widespread in the world of urban designers. The research process consisted of two main stages. Firstly, the detecting of changes in the Hierapolis site over time through the multi-temporal imagery acquired by the Laboratory of geomatics for Cultural Heritage with UAVs in the years 2015 and 2019. The detective work was done by extracting, processing and presenting the 3D data in different ways using various tools related to geospatial analysis and photogrammetry. In the second step, after discovering the main areas excavated in the period 2015-2019, an examination is made to derive information that supports archaeologists in planning the areas to be 'excavated' with non-invasive means. The central structure of the thesis starts from the description of the historical, cultural and natural values of the Hierapolis site with a focus on the North Necropolis – the area of interest. Then, the available materials that were used in the different phases of the work have been introduced. The materials mainly include multispectral images acquired by a UAV from a survey conducted in 2015, and an orthomosaic and related DSM from a survey carried out in 2019. An updated CAD dataset of the area for 2015 and relevant literature were also valuable to my research. Based on the available materials, a review of various methods was performed. These methods concentrate on the types of information that can be extracted from the raster products (orthomosaic and DSM) and the vector products (CAD files or GIS features). Using these two types of materials allows to examine the effectiveness of the different bands acquired by the UAV, the importance of multispectral information and the usage of vector features in a GIS environment. Most of the obtained results represented in the paper indeed support the general claim. It can be deduced that recent Geomatics technological tools may provide possible scientific solutions for assisting the archaeologists with monitoring and documentation of the site. The research encourages a consistent development of geomatics in the archaeological field, hand in hand with gradually enhancing its technologies in many other fields of application such as the world of urban design.