Digital Elevation Model (DEM) generation using airborne SAR interferometry (InSAR)

Information about the shape of the Earth’s surface is important in many applications as it helps users to visualize and analyze geographic problems accurately in 3D. This paper focuses on the InSAR technique of generating Digital Elevation Models (DEM) by using InSAR data acquired from an airborne platform. The data cover a study area of 4 km x 3 km located in Thetford Forest, East Anglia, United Kingdom. They were collected by an experimental SAR sensor (E-SAR) carried onboard a DLR aircraft as part of the UK’s first SHAC campaign in July 2000. This study demonstrates that DEM generated from airborne InSAR data are highly correlated with ground topography. Ground elevations in the test area were measured using the Global Positioning System (GPS) and Total Station techniques. It was found that the RMS error of the InSAR-derived DEM was less than 2.0m. The possibility of generating topographic elevations for under forest cover was also examined. Ground elevations were derived from the Ordnance Survey (GB) 1:10000 digital contour map, while the UK Forestry Commission’s tree height model was used to estimate tree heights. It was thus possible to estimate the penetration depth of the radar signal into the canopy. It was found that penetration depth increases with the age of the trees.