I m processing Sentinel-1 image using StaMPS. My results in term velocity and displacements values are reasonable.
But i have a problem with PS arrangement !
When i plot velocity map on matlab it’s OK, PS points will appear like small pixels on the mean amplitude. Below a good example of a bridge where PS are located on its surface.
When i exported velocity map to GIS using a csv file by :
load(‘ps2’,‘lonlat’) % load longitude & latitude matrix
load (‘hgt2’) %load height matrix
load(‘ps_plot_v-dso’,‘ph_disp’) %load velocity values
gis_data=horzcat(lonlat,hgt,ph_disp); %concatenate longitude latitude height and velocity
dlmwrite(‘GIS.csv’,gis_data , ‘delimiter’, ‘,’, ‘precision’, 9); %export in csv format with a precision of 9 decimals
After opening the csv file on Qgis PS look like this :
-PS are arranged along range direction ! Globally groupes of PS is located on building area but single PS points within a groupe are not located on building edge for example.
-Minimum distance between PS is about 4m in range direction and 14m in azimut direction. knowing that pixel size for sentinel 1 is 5m (range)x 20m azimut. How that is possible ?
Its apparently a problem of orthorectification. lon lat layers are normally orthorectified in snap while exporting (using SRTM 1Sec) !
Are lon lat values in ps2 matrix orthorectified during Stamps processing ?
hgt2 contain altitude values from exported DEM or altitude values are recalculated and rectified after DEM error estimation ?
PS : i used Snap2stamps package: a free tool to automate the SNAP-StaMPS Workflow for interferograms generation and Stamps v4.1b for PS processing.