Products Radar Remote Sensing
Remote sensing by satellite-borne SAR sensors
GAP srl has developed and successfully applied in several projects the proprietary SPINUA © (Stable Point Interferometry over Unurbanised Areas) algorithm. This belongs to the family of Persistent Scatterers Interferometry (PSI) processing tools.
SPINUA © algorithm has been applied and tested on both large urban areas and scarcely urbanized regions for monitoring both instable areas (affected by subsidences, landslides, post-seismic deformations), and instable infrastructures (dams, bridges, railways, pipelines, etc.)
Innovative aspects and some ad hoc solutions have been developed and tested, which render the tool flexible and suitable also for applications to areas with low densities of natural radar reflectors. In particular, original algorithms have been developed for the PSI techniques and have been successfully applied to many test sites affected by ground instabilities in or close to urban areas but optimized also for poorly urbanized areas.
SPINUA © implements a DInSAR algorithm to measure topography exploiting the phase difference between the backscattered microwave signals of two images received from slightly different satellite orbits. If the two SAR acquisitions are also displaced in time, and a priori information about terrain topography is available, displacements occurred between the two acquisitions with respect to the known topography can be detected with millimetric accuracy. When a series of SAR acquisitions is available over a site, it is possible to combine them into several differential interferograms, which allow to follow displacement trends through time (multi-temporal DInSAR).
SPINUA © overcomes the limitations of conventional InSAR and extends the applicability of radar interferometry from regional to local-scale geology investigations of ground instability. SPINUA © delivers highly accurate measurements of ground displacements over long time periods. Atmospheric effects and topographic influence can be removed using 25 or more SAR images. The high-level of error compensation allows the generation of time series charts, visualizing the evolution of the displacement of each stable point. Ground deformation is measured with a precision of 1.5 mm/year along the line of sight of the satellite (which for ERS and ENVISAT is close to the vertical). Horizontal localization precision of measurement points is 10 m
SPINUA © can also detect millimetric ground motion in areas utilized for oil & gas extraction, storage, pipelines and can be used also for monitoring the surface uplift in Steam Assisted Gravity Drainage production, ground motion due tochanges in underground CO storage pressure for CO emission control and the stability of offshore anchored platforms.