Hi, I’ve been reading the SNAP help trying to work out how to do what I want, and I find it’s generating as many questions as answers for me. I thought I would explain my requirements here and see if anyone could give me some tips about how to achieve them.
I have some data, which I am happy with, that lets me find a land use category from a latitude and longitude. I also have a sequence of about ten level 1 SLC 1x1 Sentinel 1 IW images of almost exactly the same area downloaded from the Copernicus open access hub (and I intend to download more such sequences).
I wish to access my required data in C or Matlab, but I’m not sure of the extraction strategy, or how much of the extraction process I should do in C or Matlab, and how much in SNAP, so I’m just going to describe the data I want and hope that someone can advise me. I want to select about ten small patches (each perhaps 10 x 10 pixels) for each represented land use category within the intersection of the coverage area of my image sequence, and for each patch I want access to i) the complex amplitudes for each pixel in the patch calibrated to \sigma_0, ii) a look direction for each patch (or at least an incidence angle).
From reading the help, My guess is that I should use the Graph-Builder, and that I need at least the following steps, but I’m not sure of the order: a) Read, b) Apply-Orbit file, c) back geocoding to a single master, d) range shift, e) azimuth shift, f) Split for polarisation and swath (maybe just take one for simplicity) g) Split for burst (maybe just take one for simplicity) h) calibrate to \sigma_0 i) write out complex data to geoTiff?
After that, I guess I need to find a library to read geoTiff, and write out the complex amplitudes and the lat-longs and the look directions, but maybe there is a way that lets me deal with smaller files.
Anyway, I hope this is clear. Some of it is guesswork. Thanks for any guidance you can give me.