Different Approaches For PSI Target Characterization For Monitoring Urban Infrastructure

Persistent Scatterer Interferometry (PSI) can yield a positioning accuracy in the order of metres and millimetric deformation trends by exploiting coherent pixels. How- ever, associating a Persistent Scatterer (PS) to a specific target such as a pole, building, ground or a building-to-ground interface is not straightforward [4]. If one could precisely associate each PS to an actual target, the observed deformation can be better interpreted, thereby creating a new range of applications. One such application is to find the relative motion between a building and the ground to estimate the stress on underground infrastructures like pipes used for gas or sewer systems, potentially leading to damage or even gas explosions when left un- noticed. This building versus ground differential (BGD) motion estimation can be used as one of the metrics to identify potentially unsafe urban zones and alert respective stakeholders. To detect BGD motion, the reflections from buildings, ground, and the building to ground interfaces have to be separated. In our previous approach [1], we combined various types of information such as height estimated from PSI, amplitude scattering pattern variation over various incidence and squint angles, and polarimetric information to characterize and to detect the BGD motion. But polarization data is not available over all the regions and hence the BGD detection capability without using polarization data needs to be assessed. Towards the goal of BGD motion estimation different approaches are introduced. These approaches are compared for target characterization and interpretation of deformation phenomena over a few urban areas in the Netherlands using TerraSAR-X timeseries and polarimetric data.