Satellite Radar Interferometry for DEM Generation Using Sentinel-1A Imagery

Abstract

Interferometry technique generates an elevation model using interferometric image pair acquired by synthetic-aperture radar (SAR). The present article has investigated the potential of Sentinel-1 SAR imageries for topographic analysis. Interferometric SAR utilizes phase difference information from complex-valued interferometric SAR images captured at two different imaging positions. Extracted topographic information is highly useful in various applications like crustal deformation, glacial movement, deformation studies, and topographical analysis. Various satellite systems such as RADARSAT, ERS, TerraSAR-X, ALOS PALSAR, and Sentinel-1 acquire interferometric images. The present article examines the DEM generation using the interferometry method. Sentinel-1A satellite datasets have been used to generate digital elevation model (DEM) for Tonk district and surrounding area. The study area comprises various land cover features including built-up, agriculture land, water bodies, barren land, and scrubland. SNAP toolbox has been used to generate the DEM using Sentinel-1A interferometric wide swath (IW) in single look complex (SLC) image format. The DEM generation process includes baseline estimation, co‐registration, interferogram generation, coherence, interferogram filtering, flattening, phase unwrapping, phase to height conversion, orbital refinement, and geocoding followed by generation of digital elevation model. Visual interpretation of derived DEM has been carried out using Google Earth. Coherence influences the accuracy of generated DEM. The quality of coherence depends on the baseline, wavelength, and temporal resolution of the interferometric pair. Pixels having coherence values greater than 0.5 have shown elevation values near to SRTM DEM values.