Fusion of optical and radar digital elevation models in the spatial frequency domain

Generation of digital elevation models (DEM) is a main issue of satellite remote sensing and is needed for many applications of satellite imagery. Traditionally the DEM is derived stereoscopically from an optical sensor image pair. With the ERS mission, SAR data became available regularly, which paved the way for a relatively new technique for DEM generation, the SAR interferometry (InSAR). Today, both, satellite stereoscopy and interferometry, exist in parallel and are applied independent from each other, although several synergies to overcome the limitations of each technique can be identified. In this paper, a procedure is introduced, with which stereo and interferometric generated DEMs are fused by taking advantage of their synergies ire the spatial frequency domain. The error behavior of stereo-optical and InSAR DEMs is different and can easily be accessed in the spatial frequency domain. It will be shown, that the frequency properties of the different sources complement each other and can therefore be used to derive a fused DEM of higher quality in terms of accuracy and interpretability compared to that of a single source. The procedure is tested by fusing four optical and InSAR DEM test pairs and proves its capability to generate improved DEMs.