PSI-HSR: a new approach for representing Persistent Scatterer Interferometry (PSI) point targets using the hue and saturation scale

Persistent Scatterer Interferometry (PSI) is a recently developed radar processing technique that enables the measurement of ground motion with millimetre accuracy. This technique makes use of an analysis of multi-temporal Synthetic Aperture Radar (SAR) images to detect stable PSI point targets, so-called persistent scatterers (PSs). These PSs are usually integrated in a geographic information system (GIS) as a standard point-based map, using colour coding on their velocities, with separation of ascending and descending data. In this paper we introduce the PSI-HSR (PSI Hue–Saturation Representation), a new method for representing PSI point targets using the hue–saturation scale. The aim was to render a unique colour for each PSI point target, based on a combination of displacements assessed along two different lines of sight. PSI-HSR provides a straightforward way to describe ground movement. To demonstrate the usefulness of this approach, an example of detecting ground subsidence in the Pistoia-Prato-Firenze basin is presented.