Evaluation of Interpolation Methods for Geonet Data Used in Interferometric Synthetic Aperture Radar

Synthetic aperture radar (SAR) imaging is commonly used to monitor civil engineering structures and analyze various phenomena in mountainous areas. Interferometric SAR (InSAR) results need to be corrected using global navigation satellite system (GNSS) based control station data to estimate the displacement of reinforced slopes. In this study, the suitability of the interpolation method for GNSS Earth Observation Network System (GEONET) data was evaluated using field survey results. Interpolation was performed using the Green's function for six different spline methods, and the accuracy was determined by comparison to geographical coordinates from virtual reference station real-time kinematic global navigation satellite system (VRS RTK-GNSS) surveying at three test sites in Chiba Prefecture, Japan. We conclude that Green's function for spline is a useful method of interpolating GEONET elevation data, and that the most accurate spline method was the continuous curvature spline in tension for a spherical surface.