How to prepare Sentinel-1 images stack for PSI/SBAS in SNAP


in the first I want to thank you for all information whose help me to start with SNAP and now busy with stamps. I work in windows environment, I installed Cygwin I ran the first script mt_prep_gamma_snap and I think it is good because all my pscands.ij files are not empty behave pscands.1.ij0. I got the following error message in running stamps(1,1).

I want your help please, I am in this error for a long time, I tried all thing from the forum and from de mainSAR group but no result.


Which stamps version do you use? Please get the last one from github.


Dear @mdelgado , during my processing i get empty PScand file with extension “ijo” :expressionless:
can you tell me the possible reason??


Normally a reason for that are empty resampled slaves or processing with errors.
Had you checked them all to verify if this had happened?



I used StaMPS-4.1-beta. and I have a trial version of Matlab R2018b. I processed my data in snap 6.0 version as showed in the forum (split-orbit-stack AND split-orbit-stack-deb-ifg-dinsar) . I tried to process the year 2017 with an temporal baseline of 6 days. I began with 11 SLC images of sentinel1A$B. The master image is choose by InsarStack tool of snap and 10 slaves images. I exported them to stamps via snap. I would like to apply PS for my data. I update the two scripts as said in the forum (mt_prep_gamma_snap and ps_load_initial_gamma)the first script mt_prep_gamma_snap did it well under Cygwin then I called matlab from my data directory. but when I ran stamps (1,1) in Matlab envorinment I got the errors I sent to you.
I’am waiting your feedback because I lost more time in until now and i don’t know what to do.
thank you for your help.


Maybe this could be the reason. I suggest you to use the mt_prep_snap provided with StaMPS-4.1b.

Moreover, ensure to have the latest plugin updates for SNAP as it was an issue with the download of the SRTM 3 arc second, that is fixed with the updates.

In addition, check slaves and interferograms to understand if everything was successful during the processing or not.

I hope this helps.


i just tried with just 2 images, one master and the other slave, i export them i get for files: /dem, /diff0, /geo, /rslc. after i ran the script mt_prep_snap in cyqwin. i got also a list of patch files as show in the picture.

i saw that the file “ps_parms_initial” is empty. while all patches are not.
. when i ran stamps(1,1) i got the same error as before

i hope you can find me any hint.
thank you


How many the total number of your images?


hi falahfakhri,

thank you for your answer, well, i just tried with 2 images but before i tried with 16 interferograms and also just with 11 interferograms but the same problem.


Using only (2) images to apply PSI is not accepted at all, this is the first point, the second issue I’d like you to do STEP BY STEP, to find out where is the error ? In Case it is occurred,

So, if it possible to increase your images to (20) images at least, it is fine, however your case 16 it is acceptable,
The second thing is apply this approach step by step ,
-Save each single item in a separate folder named by its date yyyymmdd
-Apply Split
-Apply orbit
-Backgeocoding by selecting the master to be the first one and the slaves are following,

  • Apply ESD
  • Apply Deburst (The first item is ready to by exported to StaMPS and waiting the following one…)
    -Create Interferograms starting from the ESD step,
    -Apply Deburst
  • Apply Topo phase removal (Now the second item is ready to be exported)

In each step above try up to open and check up your product,

Now, we are in StaMPS,

As our colleague @mdelgado mentioned in his post, be sure from which Version of StaMPs are you using, according to his suggestion to use

Also he mentioned an important thing

As I explained to you above, hope it is helpful,


Thank you for yours answers,
I am now trying to do again de same work, i choose just 2 images for PSI because i would like to verify where is the fault and to be sure that the first step of matlab can run. I will follow all the steps you give to me now and let you know my output.


hi FalahFakhri,
i just finished the process you told me but I did it for 2 images Sentinel 1. I want to be sure from the working of the process correctly, Hellas, I got errors. the first one is: I choose just one burst but “esd” didn’t work well , I took 2 bursts and the process work well in SNAP also the export to stamps, The first script ran good in Cygwin (I think), the second one stamps(1,1) shows error as follow.



Let me ask you a question,

What is the reason of applying stamps(1,1)? And how it works, or what is behind this script?

These questions for you to think about the scripts goal, not to answer me.

The other issue, I’m not sure about the validity of running StaMPS scripts , under cygwin, because many of other colleagues faced up this problem before , you could find their complainants using StaMPS under cygwin.


hi, I saw it in the forum that colleagues talk about difficulties of working in Cygwin environment. but that is what I have, I have no Linux , I have a windows computer. yesterday one colleague tried to install for me VM via oracle virtual Box but it didn’t succeed. i want to apply PSI approach with the materials that I have.
stamps(1,1) is used to upload all information such as computed amplitude dispersions , baselines information, heading,… in the aim to store them in a various workspaces.
but if stamps(1,1) didn’t run, I can not to go to the next step. thks


Have a look at the solution of our colleague


Hello everyone
I have a big problem that has been bothering me, just that I can’t confirm the correctness of PSINSAR.
The following figure shows the “u-dm” got by using the ps_output instruction of STAMPS, which means the amount of displacement in each time period.

I used EXCEL to list them, but found that displacement values are fluctuated at the same locate /different times .
I think it is wrong, because against local GPS data, it should be a decline, not ups and downs.GPS data like following figure.

Does anyone have any advice, I will be very thankful.


I can use ps_plot in StaMPS 4.1-beta_20180814.
I have had an excess matrix before. I remember that because there is a NAN in the ps2.m, you can replace the original STAMPS with the correction file posted in
You can refer to!searchin/mainsar/$20NAN|sort:date/mainsar/jG1JuPTLp1Q/Rm_YTx2bAQAJ


I dare to change the title, as this thread is not anymore only for SNAP 5.


Hello @m477h145 do you solved it ? I have similar error, my Initial gamma threshold is 1.0 and i have 0 PS selected initially and 0 PS selected after re-estimation of coherence.

Thank you


Please check all the interferograms using SNAP. Normally that could be caused by one corrupted ifg