Validation of Sentinel-1A and AW3D30 DSMs for the Metropolitan Area of Istanbul, Turkey

In space-borne remote sensing, one of the most significant tasks is the three-dimensional (3D) surface modelling performance of optical and synthetic aperture radar (SAR) satellite missions. In this study, the quality of Sentinel-1A (S-1A) and Advanced Land Observing Satellite (ALOS) World 3D 30 m (AW3D30) Digital Surface Models (DSMs) was comprehensively analysed. In addition, 1 arcsec Shuttle Radar Topography Mission (SRTM) C-band DSM was validated for better interpretation of the results. A project area including various land cover classes was selected in Istanbul, where a reference airborne laser scanning DSM is available. Optimal S-1A interferometric wide (IW) swath SAR pairs were determined and a 15 m gridded DSM was generated by interferometric processing. AW3D30 and SRTM DSMs were obtained from JAXA and NASA. In the analysis, the absolute and relative vertical accuracies of the DSMs were validated for all land cover classes with a model-to-model comparison to the reference. In addition, the influence of terrain tilt was investigated using a threshold terrain inclination of tan−1 0.1 (5.7°). Height differences from the reference were visualized by colour-coded height error maps. Vertical profiles and contour lines showed the morphologic character of the DSMs. The results demonstrated that the absolute vertical accuracies and morphologic details of AW3D30 are superior to those of S-1A and SRTM.