Coregistration of Cosmo-SkyMed Products

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#30

yes, you can then proceed :+1

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#31

Hello. I might have another problem. after co-registration i’m trying to do the interferometric formation. I left the predefined parameters, and clicked run. after hours ( very much hours),I don’t think the process finish well. I tried again changing something, but the result is the same.
First, there is no new product in the product explorer window ( after the process, usually a new product is created).
Secondly, it does not show the time it took to process(in red, in the run window).
Thirdly, when I click in the Bands to se the coherence ( or the phase), what i see is only a rectangle image and not a square ( as the first image is a square).
After this I noticed a red stop sign at the right bottom of the snap window, and this is what it shows:

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#32

have you tried to make a subset after coregistration (rather small, just for a test) and run the interferogram generation again?

I wonder if it is a matter of computing capacities or a data processing error.

#33

i’ll give it a try. I have to process the whole image, that’s why I haven’t considered the subset

#34

you were right. my pc couldn’t handle all that process. i tried to subset it, and it works perfectly. so you think, it’s better to work on different subset ?

#35

alright. Just limit the size of the stack as much as possible.
There are also some settings to check for increased performance of SNAP - could be worth a try.

For PS processing the stack should contain all dates at once so your only option is to limit the area and to increase processing power.

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#36

Hello! I have some questions related to this topic.

  1. I have used DEM assisted coregistration with subset of CSK images. I selected a master (May 2017) and i made 2 coregistrations: “only year 2017” and “years 2016-2018” (with the same master). I obtained a different result for the same 2017 MM-slv couples? How could it occur?

  2. I tried also to avoid subset, but I obtained a full-frame coregistrate with a shift (always by using the DEM assisted coregistration); the area has a lot of mountains; does it affect the DEM assisted coregistration or could effectively be used?

  3. Is it possible to process 3 years of CSK images with the same master or it is necesary to process each single year?

Thanks in advance for the support

#37
  1. What do you exactly mean by “a different result”?
  2. Strong topography is good for DEM based coregistration
  3. You can input all images for the coregistration at once and they will be coregistered to the master
#38
  1. When I make the RGB composition (MM / SLV) for the 2 coregistrations (“only year 2017” and “years 2016-2018”) they seems different also if MM and SLV are the same
  2. Ok! Thank you. But what I have to change when I found a shift? Sometimes, also strange triangular artifacts affect the coregistrate
  3. Ok, but for CSK images what temporal range could you suggest to avoid decorrelation?
#39

I suggest another input DEM then. Have you selected SRTM 1 ArcSec? You can also download (and mosaic) one yourself and check it for errors before you use it as an external DEM.

#40

I have used both DEMs (SRTM 1 and 3 ArcSec).
By using an external DEM, Is it necessary to carry out any previous transformation?
Thank you for your help

#41

no, as long as it is stored as a GeoTiff and projected in WGS84, SNAP can use it.

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#42

Hi,
Can I make a subset before coregistration? I have a CSK very large, and I want to elaborate only 1/4 of the images, so I maybe I can spare some time

#43

yes, this is possible. CSK has good orbit accuracy so the coarse matching should still work. But do not make it soo small, because you need some matching GCPs in the area.

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#44

Hello I have followed the tutorial, for cosmo skymed it is necessary to apply these two steps to export them to Stamps and obtain the map of displacements in the LOS direction?

  1. multi-looking and phase filtering techniques

  2. Phase Unwrapping: Unwrapping in SNAP follows distinct steps:

    1. Export of the wrapped phase (and definition of the parameters)
    1. Unwrapping of the phase (performed outside SNAP by snaphu)

or on the contrary, once the co-registration is done, It is only necesary to export direct with the operator interferometric-> SBAS / PSI-> STAMPS export

#45

multi-looking is not mandatory, also phase filtering should not be applied because StaMPS has its own way to deal with phase noise. No unwrapping if you want ot use StaMPS, only create a stack of the images and one of the interferograms.

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#46

Hi, I’m trying to work on CSK images. In particular, I have two CSK images to Coregister. I applied Radiometrically Calibration on each of them, but when I Coregister them i obtain a product with these ‘‘strips’’. What’s the problem?

PROBLEMA

#47

P.S This is only a portion of the entire product.

#48

What is the exact product type?

#49

Hello @ledi_04 ,
I used snap + stamps workflow with sentinel 1 product. Currently I’m approaching CosmoSkyMED images. Can you please provide me some tips about interferogram generation?

I read about it, however, I can’t fix it. As I read in the forum, for CSK products those three steps are sufficient to generate the four directories for stamps:

(-subsetting)

  • coregistration
  • interferogram
  • stamps export

However, I always face these problems:

1- when I run “stampsexport” the error is that “…the band i_xxxxx is already present…”. It is an error that i faced also in the past using sentinel-1 : as suggested in the forum, I just delete those bands from the coregistered stack.

Then I run “stampsexport” again; however, now the error has become:

2- “… the 2 products must be a stack and an interferogram…”; seems that by removing those bands the first product is no more a stack.

Can you please give me a more accurate description of each step?
Thanks.

My best,
Othmane.