Improving InSAR Accuracy for Slow Deformation and Change Detection with Lidar and GPS

Interferometric Synthetic Aperture Radar (InSAR) uses two or more SAR images over the same region for mapping ground surface displacements through time. InSAR displacements are relative to a reference point due to the 2π phase ambiguity that from unwrapping, and as a result ground control points (GCPs) are often used to calibrate the displacement model and obtain absolute measurements. Errors in InSAR time-series are typically measured with respect to the reference point, but absolute errors are not currently well constrained. To develop absolute error models for InSAR, we generate Sentinel-1 InSAR time-series for Belleville, Illinois and compare time-series with Global Navigation Satellite System (GNSS) and Light Detection and Ranging (LiDAR) displacements. Both GNSS and LiDAR data showed complementary results with the InSAR measurement, demonstrating the advantages of combining InSAR with small scale LiDAR or GPS measurements to improve InSAR accuracy.