Mapping subsidence in Tianjin area using ASAR images based on PS technique

By identifying temporarily stable natural reflectors or persistent scatterers (PS), PSInSAR (Persistent Scatterers for SAR Interferometry) technique can analyze this subset of pixels in SAR images, even with long temporal and space baselines, to get high accuracy deformation measurements. We implement the PSInSAR process that is briefly summarized in this paper and apply this method in Tianjin area to detect the deformation phenomena using ENVISAT ASAR images. Calibration of ASAR images helps us select more PSC and using calibrated backscattering coefficient threshold we can discard the pixels whose amplitude are relatively stable while whose backscattered signals are weak and incoherent. Results obtained by processing 14 images show the distribution and the relative deformation value of the displacement field. The estimated linear velocities of PS are not accurate enough because of the relatively small number of images.