What does the PS Technique consist in?
The PS Technique consists in a series of numerical elaborations of radar satellite data, during which the data is studied statistically and noise effects like disturbance due to the atmosphere, errors in the reference DEM, etc. are removed. At the end displacement values of points on the ground called PS are obtained. To apply the Technique it is necessary to have at least 25 30 radar images over the area of interest. In summary, the Technique consists of the following steps. First of all images are focalized. Focalization results in an increase of image resolution. Then the radar images are registered to an image chosen as master. Intensity values are normalized to make the various acquisitions comparable. Then the ratio between the average intensity and its standard deviation over all images is calculated; when this value exceeds a certain threshold (usually 2.5 or 3) it is indicative of a candidate PS. All candidate PSs are called PSC (Permanent Scatterers Candidates). At this point
