Height-Constrained Planimetric Geolocation Error Compensation for Elevation Refinement After InSAR-DSM Block Adjustment

Large-scale accurate digital surface model (DSM) generation is a key application of interferometric synthetic aperture radar (InSAR). Further refining the elevation by compensating the planimetric geolocation error after InSAR-DSM block adjustment remains challenging. To address this, a compensation method leveraging readily available elevation data was proposed. Relative offsets between the two DSMs were transformed into offsets relative to the reference DSM, followed by enhanced DSM mosaicking. For the first time, an optimization method was integrated with statistical adjustment (SA) for absolute offset determination. Experiments with TanDEM-X InSAR datasets near Guangzhou, China, demonstrate that: 1) the hybrid norm was identified as the optimal objective function, achieving the highest accuracy (total bias root mean square error (RMSE): 0.005 pixel) when combined with SA; 2) incorporating InSAR quality parameters and border handling enhanced fusion accuracy, while sorting DSMs by ascending Euclidean distance significantly reduced memory usage; and 3) the 90% relative elevation bias in along-track DSM overlaps was reduced to 1.51 m (an 82% improvement). The terrain-related elevation bias was corrected, yielding a mean and RMSE of 0.09 and 3.18 m, respectively. The compensable offset range was approximately 0.001–123 pixels. These results demonstrate the effectiveness and applicability of the proposed method.