is it possible to combine ascending and descending Sentinel-1A GRD IW VV data in a simple way, in order to increase the amount/availability of images over my area of interest? What I am thinking of is to follow such an approach (for each of the Sentinel-1A GRD IW VV ascending and descending data acquired):
Radiometric - Calibration;
Radiometric - Terrain Flattening
Geometric - Range-Doppler Terrain Correction.
After this I should have gamma0 for both the descending and the ascending data. At this point, could I simply average the two gamma0 data if I want to use both the images (providing that they are acquired with little time difference).
In theory that should work but since the current implementation of Terrain Flattening does not work properly you might run into problems in hilly/mountainous areas. On almost flat terrain the approach should work already now.
Even if the terrain flattening works, how we can combine Asc and Des image values where two images have different sizes. Even though these two images are taken from the same area of interest, they do not overlap completely. In my dataset, Asce image covers a larger area and include some major parts of Descending image.
Now, I am familier with the procedure for Sentinel1 Snap-StaMPS PSI (SLC) but by using one orbit (descending or ascending). I need to retrieve east-west displacements so I need to use both orbits. My question is how to combine them to get the east-west displacement?. What are the required additional steps?. Any tutorial, please?. Thank you.