Assessment of GNSS-Based InBSAR Deformation Monitoring Using GB-SAR and D-GNSS Measurements

GNSS-based InBSAR can be used for 3D deformation monitoring due to its remote sensing capability, simultaneous use of multiple transmitters of opportunity, and high-accuracy potential. Mature GB-SAR and D-GNSS measurements can be used for comprehensive accuracy assessment, which has become a prominent focus in recent research. However, inter-system accuracy has not been fully assessed due to DEM errors, resolution cell variance, and limitations in accuracy mapping. This paper proposes an accuracy assessment algorithm for GNSS-based InBSAR. First, the global DEM error is accurately estimated by associating multi-angle images to correct the positions of inter-system PSs. Second, the intersection of resolution cells is introduced to address inter-system resolution cell variance and obtain inter-system coregistered PSs. Third, a mathematical operator model is developed to map different deformation directions for inter-system accuracy assessment. Raw data verify the validity of the proposed algorithm and model. In the first experimental scene with continuous deformation, the system achieves an LOS accuracy of 3.1 mm compared with GB-SAR. In the second experimental scene with invisible deformation, it achieves 3D accuracies of 2.2, 2.5, and 4.3 mm using D-GNSS as the reference and an LOS accuracy of 2.6 mm using GB-SAR as the reference. The results show that the method provides an effective solution for inter-system accuracy assessment.