Abstract
Synthetic Aperture Radar (SAR) satellite systems may give important contribution in terms of Digital Surface Models (DSMs) generation considering their complete independence from logistic constraints on the ground and weather conditions. In recent years, the new availability of very high resolution SAR data (up to 20 cm Ground Sample Distance) gave a new impulse to radargrammetry and allowed new applications and developments. Besides, to date, among the software aimed to radargrammetric applications only few show as free and open source. It is in this context that it has been decided to widen DATE (Digital Automatic Terrain Extractor) plug-in capabilities and additionally include the possibility to use SAR imagery for DSM stereo reconstruction (i.e. radargrammetry), besides to the optical workflow already developed. <br><br> DATE is a Free and Open Source Software (FOSS) developed at the Geodesy and Geomatics Division, University of Rome “La Sapienza”, and conceived as an OSSIM (Open Source Software Image Map) plug-in. It has been developed starting from May 2014 in the framework of 2014 Google Summer of Code, having as early purpose a fully automatic DSMs generation from high resolution optical satellite imagery acquired by the most common sensors. <br><br> Here, the results achieved through this new capability applied to two stacks (one ascending and one descending) of three TerraSAR-X images each, acquired over Trento (Northern Italy) testfield, are presented. Global accuracies achieved are around 6 metres. These first results are promising and further analysis are expected for a more complete assessment of DATE application to SAR imagery.
Highlights
Given their complete independence from logistic constraints on the ground and both weather and illumination conditions, Synthetic Aperture Radar (SAR) satellite systems may give an important contribution in terms of Digital Surface Models (DSMs) generation
SISAR (Software per le Immagini Satellitari ad Alta Risoluzione), a scientific software developed at the Geodesy and Geomatics Division of the University of Rome “La Sapienza” (Capaldo et al 2011) has been adopted
To be sure that no significant error is introduced with the Rational Polynomial Coefficients (RPCs) use with respect to the zero Doppler SAR model, an assessment using the Tie Points supplied by the vendors and available in the metadata files is carried out for each image
Summary
Given their complete independence from logistic constraints on the ground and both weather and illumination conditions, Synthetic Aperture Radar (SAR) satellite systems may give an important contribution in terms of Digital Surface Models (DSMs) generation. The main advantage of the interferometry technique rely on the fact that its accuracy depends on the signal wavelenght, which is smaller than the amplitude resolution and can provide higher accuracy; on the other hand, to properly work, radargrammetry does not require coherence between images. This work is focused on the description of a new radargrammetric capability for DSMs generation, implemented in the Free and Open Source (FOSS) DATE plug-in, developed at the Geodesy and Geomatics Division of the University of Rome “La Sapienza”. The radargrammetric technique use for DSM generation is not a new topic; as a matter of fact radargrammetry was first employed in the 1950s with ground and airborne radars, and less and less exploited, due to the low amplitude resolution of SAR im-.
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