Dear Exelis Vis support My organisation Immanuel Kant Baltic Federal University recently became a user of ENVI+SARscape software. I need to understand what approaches are used in the Persistent Scatterers module. In the help files I found 3 reference. A. Ferretti, C. Prati and F. Rocca: "Nonlinear subsidence rate estimation using permanent scatterers in differential SAR interferometry". Geoscience and Remote Sensing, IEEE Transactions on, vol. 38, no. 5, Part 1, Sept. 2000, pp. 2202 - 2212. A. Ferretti, C. Prati and F. Rocca: "Permanent scatterers in SAR interferometry". Geoscience and Remote Sensing, IEEE Transactions on, vol. 39, no. 1, Jan. 2001, pp. 8 - 20. A. Hooper, H. Zebker, P. Segall, and B. Kampes: "A new method for measuring deformation on volcanoes and other non-urban areas using InSAR persistent scatterers". Geophysical Research Letters, vol. 31, December 2004. But the methods described in second and third papers are different. Italian researchers described PSInSAR(tm) method, whereas Andy Hooper gave first results of StaMPS/MTI application in his paper. Could you please answer a few question about PS module in SARscape: 1. What method is used for PS selection. 2. What approch is used for topographic error reducing. I notice features caused by topography on resulting displacements map in some areas even with quite big default parameters (Min/Max residual height). Especially for buildings where the height of objects can be detected like displacements. 3. What method is used for phase unwrapping. Thanks in advance.