A fusion of digital elevation model based on interferometry SAR technique from ascending and descending path in urban area

The height of the earth's surface can be measured using synthetic aperture radar (SAR) images using interferometry (InSAR). The InSAR method uses phase information to produce the height of the earth's surface. The accuracy of the DEM produced by InSAR depends on the shadow, the layover area, and the coherence of two SAR data. This paper proposes a technique for combining DEM derived from the InSAR method from ascending and descending paths using high resolution TerraSAR-X/TanDEM-X. Generating DEM was done by the InSAR method which covers the same test area and came from one pair of ascending TanDEM-X images and one descending pair of TerraSAR-X. The combination of the two DEMs from the ascending and descending path has been done by assessing the weighting factors so that the accuracy of the DEM can be increased. The weighting factors are calculated from the height error map, layover and shadow map. The height error map is calculated from the interferometric coherence with geometrical considerations and the layover and shadow map is calculated using TerraSAR-X/TanDEM-X DEM. The images pairs with 33 angles and 37 degrees were used in this study for the InSAR method in urban areas (Jakarta city). The experimental results show a significant reduction in missing pixel counts due to layover, shadow and low coherences after combining.