SAR INTERFEROMETRY BASED DISPLACEMENT MAPPING OF CULTURAL HERITAGE SITES

摘要

Synthetic Aperture RADAR remote sensing has been widely used for mapping of archaeological features which include cultural as well as natural heritage sites. In the current scenario, SAR Interferometry has the potential to measure displacement and elevation of the objects appearing on earth's surface. Prime focus of present study is to evaluate the potential of C-Band SAR interferometry for subsidence mapping of cultural heritage sites. For this study, Rohtasgarh Fort was selected as study site and C-Band interferometric pairs were used which were acquired in March and April' 2017. Interferometric processing for interferogram generation, coherence and phase unwrapping was performed to generate a displacement map. High value of coherence was observed on the fort boundaries because this behaves as stable scatterer which wasn't changed during second acquisition and low coherence value was recorded for vegetation inside and outside the fort. Displacement map was generated from unwrapped interferogram with 0.3 threshold value of coherence. Most areas in and around the fort hadn't shown any displacement but an upliftment of 10mm was seen inside the fort premises. Upliftment in displacement map in fort premises may be possible either due to increase in moisture or dust storms while subsidence outside the fort premises can be due to loose debris washed away by rain.