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

Thanks @jozep for your reply

Path variables??? Please, do you can explain me?

You are unable to run the command as the system doesn’t know where to look for the mt_prep_gamma script file.

Open a Terminal window.

To add the directory of the mt_prep_gamma script (in this case the StaMPS bin directory) to the path list type:


You should now be able to execute the command.

To check the updated environment variable path list type:

echo $PATH

The newly added path should appear in the list.

To run the command and avoid any errors you can format it as follows:

mt_prep_gamma [yyyy/mm/dd - of master scene] [output_directory] 0.4 2 2 50 200

(given that you want to leave the default prep options)

Good luck

Hi @kouhartsiouk

Thanks for your reply, before I make your suggested me, I have that to install the tcsh program!!! :disappointed_relieved:

Hello everyone,

I followed the steps which Katherine provided and get weird wrapping result in StaMPS as below. Do you have any suggestion on this issue? Btw, unwrapping or plot any figure will have similar issue.
Many thanks.



The workflow described in this post (and the ones referring to it later on) is outdated and no longer recommended, because new versions of SNAP and StaMPS have been released. Please have a look at this updated list of instructions: StaMPS - Detailled instructions

Hi all,
Recently SNAP6.0 has been released, and by chance @Mehdi use the “oethorectified lat/long” options to solve his problem. And now I test this method and find that this new option can solve the shift problem and can avoid Terrain Correction (TC) step in PSI. @katherine @annamaria @bayzidul @ABraun
Here is the new Interferogram Formation window in SNAP6.0:

After finish this step, elevation and lat/lon band will be generated in result product.

Start from Deburst step, we get Stack_deb, then create a subset, get Subset_Stack_deb, form interfeorgrams as the first picture showed and get Subset_Stack_deb_ifg. And then use Subset_Stack_deb and Subset_Stack_deb_ifg to export to StaMPS.
And that’s all, all the things have been done. Add Elevation band, geocoded and topo_removal are doing together in interferogram formation step, TC are avoided, lat/lon file can export correctly without saving to GAMMA format.

Here are some results:
1.use SNAP6.preview4 and without TC:

2.use SNAP6.preview4 and TC:

3.use SNAP6.0 oethorectified lat/lon and without TC:

Note: I use different parameters when export to Google Earth, and only about 20% PSs are shown in the picture, so don’t be surprised that PSs location are not exactly the same.

In SNAP6.preview4 or preview5, without TC there are exist shift problem. And use SNAP6.0, shift problem has been solved and TC are no more needed.

Have Fun!


that’s just fantastic, thanks for testing!

One question about the stack: Did you create pairwise stacks of AB AC AD… and merge them with the back geocoding as originally suggested? Because this creates a quite redundant stack with A in it multiple times and I wondered if this is the best way to do it.

Dear ABraun,
I follow the step as katherine suggested here:

And my post can be seen as a suggestion for the orignal way.

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Dear Fei,
Thank you so much for sharing your wonderful experience! Due to our cooperation the workflow between SNAP and StaMPS becomes more and more friendly! The next problem seems to be the possibility to create a stack of pairs with different masters (being resampled to one “supermaster”) and export such a stack to StaMPS to execute the StaMPS SB (Small Baselines Processing). StaMPS SB will be very useful in rural areas where StaMPS PS permits us to identify only few PS (especially using S-1 images)…
All the best,

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Hi @kouhartsiouk @Fikretjfm

I have a problem during the processing final, the process stopped for 20170409, and when I check the folder .rslc I can see the archive 20170409 duplicate, someone had the same problem?

Thanks for advance

Dear Katherine,
Thank you for your reply, I also notice that almost all the PSs points I get are located in urban area, and get only few PSs in rural area. It’s a shortage for StaMPS PS method, and can hope SB method to improve it.
But it seems that the implemention of SBAS export in SNAP have to wait a long time…:joy:
All the best,

maybe the file was still in use by another program? Does it always happen with that date?

hi ,
have you tried to delete one of them? I havent faced such a this error.

Thank you for the test-report Fei!


in the last weeks I tried using the SNAP-StaMPS workflow for PS analysis. I found this thread which was incredible helpful. I summarized…again…the workflow, I found the summaries and hints given were great @katherine, @bayzidul, @FeiLiu, @ABraun. But latest updates of SNAP and the amount of steps are confusing, gathering and following all hints given to reach the goal.

Maybe some of you which have experience in the workflow might have a look at the summary to help improving it.

Furthermore I would really like to do all the steps with a test dataset to retrieve a valid displacement map and write a comprehensible tutorial. I do not have data for validation, hence I am just starting using interferometry. Therefore I do not know if outputs produced are valid or not…maybe someone can help me to do this, just write me a message here.

To read the summary, download the .html here and open it in your browser.
Edit: The file is no longer available, please check the instructions here: About the StaMPS category

Thank you :slight_smile:


Wow, thank you for compiling all this and of course thanks for sharing it here!

That’s great, Thorsten. We should add this to our tutorials section when it has a good status and if you allow. But then it should be at a better place where we can easier link to.
Unfortunately, I can’t help with the validation. I have no knowledge of the domain.

Hi @thho

This is an outstanding work you have done. The document is a great support to the enthusiasts. Thank you so much.
The validation is a tricky process, you can either validate your result with GPS or Levelling based reference data or you can use another software to compare. There is a lot of papers on this that might help you.

Thank you

Hi all, I have used SNAP6, and
@katherine 's and @FeiLiu 's changed script and followed the lastest workflow of @FeiLiu. I can successfully run the SNAP and StaMPS and get the final result.
However I found a new problem about DEM data from SNAP exported. It seems this DEM cannot be recognized and cannot be used by StaMPS. I added the elevation data in SNAP and can find the DEM file at the dem folder in the exported folder.
I found this problem, because of:

  1. When I try to used “ps_plot(‘v’,2)” to plot a shaded relief topo as background, StaMPS returned an error “Cannot find in this directory, parent or grandparent”
  2. When I try to used “ps_plot(‘v-a’)” to plot a result that minus topo-correlated atmosphere, StaMPS returned an error “Unable to read file ‘./tca2’: no such file or directory.”
  3. I have compared the results of “ps_plot(‘v-d’)” and “ps_plot(‘v’)”. They are exactly the same.
    It would be appreciated if anyone could help me.

Thanks for your kind replies @ABraun, @marpet and @bayzidul!

It would be great to see the final result in the tutorial section. The domain I used to store the document allows me to update it frequently. I want to avoid numerous links to different versions but one source at all. In the end a final result can easily be stored wherever it fits best.

Concerning validation, I will dive in some literature and maybe there is a SFM product which could help me…I will keep you on track. But if someone might help me, you are welcome!

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