Export selection of bursts in 2 subswaths

Microwave Toolbox
#1

Dear community,

I am operating a monitoring system which uses Sentinel-1 IW SLC products, and I have over the years accumulated enormous amounts of data. I am looking for a way to “crop” these products in order to save space, as I am in most cases only interested in a 40x40 km area.

Because I want to keep the possibility to generate interferograms with these products in the future, my strategy so far has been to simply “TOPSAR split” the product, specifying both the “subswath” and “wktAoi” as inputs according to the region of interest.
This essentially allows for me to export a few bursts in a DIM file, thereby significantly reducing the size of the stored product.

This approach however “fails” when the region of interest is overlapping onto 2 subswaths.
Indeed I have not yet found a way to export a few bursts of 2 neighboring subswaths in a single DIM file: the “topsar split” operator does not support exporting 2 subswaths, and exporting the 2 swaths in separate products and successively attempting to merge them afterwards with “topsar merge” fails as the products should first be debursted (which I want to avoid in order keep the possibility to generate interferograms).
I suppose I could export the 2 subswaths in 2 distinct DIM files, however that’s very clumsy and not very satisfying.

I there a a way to achieve this in a more elegant / efficient manner?

Many thanks in advance for any suggestion.

#2

Maybe a graph which extracts two sub-swaths using Split, then Deburst and then TOPS Merge would be helpful?

grafik

#3

Hi ABraun, many thanks for your quick reply.

The problem is, if I deburst the products (as required by TOPSAR-merge), than I cannot compute interferograms with the exported product, which is essential for me.

(Btw, although it’s not of particular importance for this issue, I forgot to mention that I use the Python API to handle workflows.)

#4

I see. The suggested approach is then to calculate the interferogram first and then use merge.
You find a predefined graph in the Graph Processing Tool under Graphs > Radar > InSAR Graphs > TOPSAR Coreg Interferogram All Swaths

grafik
grafik882×457 48.6 KB

You can use it as a reference when you re-create this chain in the Python API, or directly call the graph XML with gpt (also from inside Python).

#5

Thanks once again for your suggestions ABraun!

Your approach shows how to generate an interferogram spanning over several subswaths. However what I am trying to achieve, is to “crop” the IW SLC products, so as to reduce the size of the product I will keep as “archive”. I’d like to keep the real/imaginary bands, and keep the product with the bursts, so as to leave me the freedom to do further analysis at a later time (INSAR is just one of the analysis I am interested in).

For now, the only way I can think of is to save 2 distinct DIM files, each storing a few bursts of the 2 susbwaths…

#6

Now I understand, sorry. You want to clip them, but also avoid deburst to leave all options for later processing.
I cannot think of another solution than leaving the split bursts as they are.

#7

Ok that’s what I feared, SNAP does not handle the export of file with a selection of bursts in 2 neighboring subswaths.

In any case many thanks for our time and suggestions ABraun!

#8

The problem you trying to solve is from long time “nice to have”, but by now it was not realized in the S1 repository. I’ve asked several times why it is not possible to get single swat, but the answer was that currently this could not be done. I hope next time soon this shall be made available to the community.