Linear and Non-linear Long-term Terrain Deformation with Dinsar (cpt: Coherent Pixels Technique)

RESUME In this paper, an advanced technique for the generation of deformation maps using SAR (Synthetic Aperture Radar) data is presented. The algorithm, called the Coherent Pixels Technique, estimates the linear and non-linear components of the displacement, the error of the Digital Elevation Model (DEM) used to cancel the topographic terms, and the atmospheric artifacts from a reduced set of low spatial resolution interferograms. The pixel candidates are selected from those presenting a good coherence level in the whole set of interferograms and the resulting non-uniform mesh tessellated with the Delauney triangulation to establish connections among them. The linear component of movement and DEM error are estimated adjusting a linear model to the data only on the connections. Later on, this information, once integrated to retrieve the absolute values, is used to calculate the non-linear component of movement and atmospheric artifacts with alternate filtering techniques in both temporal and spatial domains. The method presents high flexibility with respect to the required number of images and the baselines length. However, better results are obtained with large datasets of short baseline interferograms. The technique has been tested with ERS SAR data from an area of Catalonia (Spain) and the Campi Flegrei area (Naples, Italy) and validated with on-field precise levelling measurements.