Abstract
Abstract. In densely vegetated mountainous areas, the height measurement accuracy of SAR interferometry is contaminated by phase unwrapping errors and volume scattering effects of the vegetation. Aiming at this limitation of InSAR, we propose the high-resolution radargrammetry-assisted SAR interferometry method to achieve high-precision topographic mapping. Specifically speaking, we propose to apply our methods in the TerraSAR-X images with a repeat-pass InSAR pair and a stereo radargrammetric pair sharing the same master image which can avoid radarcoding the reference DEM and minimize the acquisition time discrepancy between the reference DEM and InSAR data. Compared with medium-resolution reference DEM, the high-resolution radargrammetric DEM can simulate the reference topographic phase more accurately which reduces the InSAR phase unwrapping errors. In addition to the removal of the reference topographic phase, we automatically select reliable points from radargrammetric DEM for calibrating the absolute InSAR phase offset. Finally, we fuse the radargrammetric DEM and InSAR DEM together with weights determined from theoretical height error to fill in data voids in InSAR DEM. The experimental results show that the DEM generated by radargrammetry-assisted SAR interferometry has better height accuracy than DEM generated by either single method.
Highlights
As one of two major approaches (SAR interferometry and radargrammetry) using SAR remote sensing data for topographic mapping (Thierry Toutin 2000), InSAR makes use of the interferometric phase information to extract the terrain height accurately, which has been successfully applied for global DEM generation by SRTM (Shuttle Radar Topography Mission) and TanDEM-X (TerraSAR-X Add-on for Digital Elevation Measurements) mission (Krieger et al, 2007)
We propose the high-resolution radargrammetry-assisted SAR interferometry to generate DEM at vegetated mountainous areas
The proposed method is applied on Stripmap mode TerraSAR-X images with an InSAR pair and a radargrammetric pair sharing the same master image
Summary
As one of two major approaches (SAR interferometry and radargrammetry) using SAR remote sensing data for topographic mapping (Thierry Toutin 2000), InSAR makes use of the interferometric phase information to extract the terrain height accurately, which has been successfully applied for global DEM generation by SRTM (Shuttle Radar Topography Mission) and TanDEM-X (TerraSAR-X Add-on for Digital Elevation Measurements) mission (Krieger et al, 2007). Researchers tried to generate the radargrammetric DEM from a stereo radargrammetric pair which is used to flatten the interferogram, calibrate the unwrapped phase and provide height estimates for missing InSAR-DEM values (Gelautz et al, 2003). This procedure is influenced by spatial resolution and height accuracy of radargrammetric DEM which means the mediumresolution reference DEM cannot reduce the fringes significantly at rolling terrain and the height error of the reference DEM excessing the InSAR height ambiguity can introduce erroneous phase unwrapping. With the high-resolution and high-precision radargrammetric DEM, we propose the high-resolution radargrammetry-assisted SAR interferometry method for improved topographic mapping at vegetated mountainous areas.
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