Abstract:
Synthetic Aperture RADAR Remote
Sensing technique has widely used in mapping and
monitoring of cultural and natural heritage sites. In
today’s scenario, SAR Interferometry (InSAR) is being
used to measure the elevation and displacement of manmade and natural features. This study was focused on
phase filtering to detect displacement in cultural
heritage site using space borne repeat pass SAR
Interferometry. Rohtasgarh fort, was chosen as study
site and Sentinel -1, C-Band interferometric pairs of
March and April 2017 were used. Interferometric
processing for interferogram generation, coherence and
phase unwrapping was performed to generate a
displacement map. It was however noticed that phase
noise greatly affects and deteriorates the quality of
interferogram which in turn affects the phase
unwrapping and geophysical measurements such as
displacement mapping. In this work, Modified Goldstein
filter was used for phase noise suppression and
preserving the fringe edges. Using a threshold of 0.3 for
coherence, displacement map was generated, and
Modified Goldstein Filtering was applied on it. Most of
the areas in and around the fort showed no displacement
but there was an upliftment seen at few places inside the
fort with maximum value of 10mm. Subsidence with
maximum value of 10mm was also seen in areas outside
the fort. Upliftment could have been due to water
accumulation inside the fort or dust storm while
subsidence could be possible due to lose debris washed
off by rain water.
