Using Sentinel ETAD datasets

[Christian Kohler]

Hi!
Currently we are working with corner reflectors and using ISCE in combination with MiaPlPy to analyze the time series signal of the reflectors. In order to further improve the results using Sentinel-1 signal corrections we noticed the 'new service' from ESA, the ETAD datasets (https://sentinels.copernicus.eu/web/sentinel/missions/sentinel-1/data-products/etad-dataset). In order to use these datasets the phase corrections obtained from ETAD should be aligned with the different phasemaps of the interferogram. Looking at the ISCE code we noticed that the co-registration process is pretty elaborated and we were wondering, if there is an easy way to extract the co-registration information from ISCE to use them with the ETAD data.
Cheers

Christian

Actually I had posted this question also on the ISCE GitHub page, but it seems the discussing page is not so well visited ...

[Christian Kohler]

After finding a lecture script with some hints and looking at the code I suppose:

- The translation for the first co-registration step is determined by geo2rdr and stored in the coreg_secondarys/XXX folders, the actual registration/translation is done using resamp_withCarrier

- The translation for the fine co-registration is obtained as well by geo2rdr and translation again done by resamp_withCarrier

Accordingly I suppose running the phase corrections obtained from ETAD through resamp_withCarrier, using the configuration created by geo2rdr should do what I want. Does this make sens?

However, currently I am trying to find out what would be the best way to convert ETAD datasets into some slc file I can run through resamp_withCarrier and, though maybe this is another question, what would be the standard way to open an slc file with isce and get to the data matrix within Python?

Maybe someone can give me a hint.

Cheers

Christian

[Christian Kohler]

After some more searching around in the code I probably solved most of my issues. The way I found to access image data within python is to use ....image.memMap() I don't know if this is the 'official' way to do it, but it seems working for me. And in case someone has similar question, I used createImage & finalizeImage to write slc file to disk, the according xml file can be created using image.dump(), as it concerns the swath xml file, the way I got it working was to replace the bursts array instead of trying to clear it or substitute single bursts, either one produced a broken xml file at the. Some more documentation and / or examples would have been wonderful - this is no criticism of the project in any way, I probably most documentation could be better ;-)
Besides I for now I decided to start with geo2rdr even though this takes quite some calculation time and in principle should not be necessary I didn't want to mess around too much with the xml files so I took this step as my starting point. Then currently I can run my phase corrections through the toolchain until merging them.

In case someone is interested this work, feel free to contact me.

Cheers

Christian