I’m coming back to you after some new results. I “managed” to coregister the deramped TOPS images.
I debursted the deramped images so that I can perform more common coregistration. Coregistration gave me a java_null_pointer_exception. Then I tried the DEM-Assisted Coregistration. It worked quite well. To be sure the phase information is correct, I performed interferograms using my stack of deramped TOPS SLC images. The results are pretty I guess.
I compared this interferogram with the one computed using the “classical” Sentinel-1 chain in SNAP (S1 TOPS Coregistration), meaning on reramped TOPS SLC images.
When I look at the difference between interferograms (mod 2 \pi), there’s for each burst a residual phase pattern. This phase pattern can be important.
Does this means that classical Insar processing chain in SNAP introduces linear phase ramp in random direction for every burst, or could there be another explanation?
I wish I knew. Because my area is moving fast in azimuthal direction, other biases related to the TOPSAR acquisition mode does not allow me to isolate the problem.
@qglaude I follow this topic from the beginning and would be interested in what you are trying to do with these deramped stacks. So feel free to keep us updated in here about the outcomes
(of course it is understandable if you want to keep it secret until you have officially published something with it)
Don’t feel pushed - as it is your work you have to make sure that you are the main benefitor in the first place. You can also simply post a link to the publication once it is available.
I’m using the official release of SNAP (7.0.0). I see no available updates.
Using this version, the back geocoding module looks like this :
In appearance, nothing changed compared to SNAP version 6. Should it be an additional option ? Did I do something wrong?
The results are, the real and imaginary parts of the master and slave image, with an additional band related to the deramped and demodulated phase of the slave image. Note that the master and slave images are NOT deramped.
Using @nuno.miranda’s document (equ. 15), I am able to deramp the slave image. But I notice this phase band can also deramp the master images.
For information, I performed exactly what was done here : Deramping TOPSAR SLC data. In the topic, I notice that the deramp was not working for the master. But now with SNAP 7 it seems it works
