Snap2stamps package: a free tool to automate the SNAP-StaMPS Workflow

wharfbanger · February 2, 2020, 8:11pm

Thanks Jose! I will try the longer dry season stack as you suggest as I had not thought of that. However, I still think my results are conclusive, even for the short stacks. I have uploaded a spreadsheet for you to see my results, and perhaps this will convince you that the short stacks are working 8-). The spreadsheet contains time series with plots for 3 stacks (7, 11 and 21 interferograms). The time series are for PS nearby to the powerful geothermal well (see yellow squares on maps in spreadsheet) and all show a clear and strong subsidence signal (about 40 - 60 mm per year).

Geothermal well time series for different stack sizes.xlsx (2.9 MB)

Also, I do have access to the literature and I have had a good look as you suggested. I have found a few papers where the “20 minimum stack size” is mentioned, but never properly explained. Do you have a good reference? It seems that if you have a strong and smooth subsidence signal (like a geothermal well causing subsidence), then this may be an exception to the “20 stack rule”? Do you agree?

mdelgado · February 2, 2020, 9:32pm

I hope you understand that 20 images is a good practice.

Che k in the literature many of the papers doing PSI, and then see how many images they normally use.

It may be the case using few due to data restrictions/ constraints or availability. But this is not the case for sentinel1

wharfbanger · February 3, 2020, 1:45am

Yes Jose I think I understand what you are saying, that 20 images is good practice. I thank you very much for your comments, and Snap2stamps is a great tool!

mdelgado · February 3, 2020, 6:19am

I am sure that you did and are doing a great job! Look forward to read the full story!

wharfbanger · February 6, 2020, 12:46am

Hi Jose,

I am looking at an Island volcano and get the error at Step 6 of stamps:
“Error using uw grid wrapped (line 84)
Minimum dimension of the resampled grid (27 pixels) is less than the prefilter window size (32)”

Inside SNAP I run TOPSAR-split and select 2 bursts, which I understand is a minimum for snap2stamps. I think the error is because the very small island (3km2) is completely inside a single burst, and is surrounded by a huge area of ocean (only ocean inside the other burst). Is there anyway to process small islands in a large area of ocean?

Thanks,
Mark

ABraun · February 6, 2020, 9:33am

what happens if you set the window size to 24, for example?

setparm('unwrap_gold_n_win', 24)

I performed StaMPS on a single burst already (just needs leaving out the ESD operator during the preprpocessing), so this should not be the problem.

mdelgado · February 6, 2020, 10:44am

Try to set up the window size for the unwrapping to 16. Sometimes it solves the issue.
Let us know

ABraun · February 6, 2020, 12:00pm

must the filter size be of 4, 16, 32, 64…? I haven’t thought of this.

wharfbanger · February 6, 2020, 2:13pm

Brilliant! That worked!!

Thanks!!!

wharfbanger · February 6, 2020, 2:14pm

Thanks ABraun - changing that param to 16 worked!!

hm1u16 · February 6, 2020, 3:28pm

HI Mdelgado, I have been reading your paper “Measuring Ubrban Subsidence in the Rome Metropolitian Area” and I have some questions regarding the combination of PSI measurements from ascending and descending orbits.

Would there be any issues relating to the 6 day gap between ascending and descending scenes?
Also do you have any example code or the model in ARC that you used for combining the ascending and descending PS points in the vector domain?

Additionally, when performing the PSI analysis multiple times, to develop a monitoring system similar to that as described in https://www.nature.com/articles/s41598-018-25369-w/. Is there anyway of matching up the coordinates of PS between different iterations. Say if I process with 20 scenes and then 21 scenes.

Thanks, Harry

mdelgado · February 6, 2020, 3:42pm

We have merged average LOS velocities, so no issues with the 6 day gap.
The code is based on the formulas used shown on the paper with the correspondent bibliography.

Regarding position, the PS should match pretty much (small shift might happen based on the accuracy of the software used). Otherwise they will not be PS. At least I understand it in that way.

SteffanDavies · February 21, 2020, 2:20pm

This error is because the user didn’t provide the full path to the gpt executable in the /snap/bin folder in SNAP2STAMPS. I made the same mistake by providing the path to snap/bin and not snap/bin/gpt

lukkarvalho · February 28, 2020, 9:30am

Hi guys!
I have some problem with my results on my snap2stamps package, after run the mt_prep_snap, I have no ps candidates and only 6 patches as result. About the other steps, I didn’t find any messages error. It’s like that:

and

Someone can help please or tell me where I’m making a mistake,
thanks a lot!

ABraun · February 28, 2020, 9:34am

the files in the folders are not your PS candidates. These are just the files containing their information.
Furthermore, you define the number of patches yourself, in the mt_prep_snap command.

So unless you don’t start the matlab processing and find errors, it looks all fine.

Additionally, I recommend creating a separate folder for the StaMPS processes. Simply create a new directory (at any location) and execute mt_prep_snap here. This helps you to keep the structure clean and doesn’t mix up the original files exported from SNAP (dem, diff0, geo, rlsc) with the ones created by Matlab later on.

mdelgado · February 28, 2020, 9:37am

Please check the interferograms and the amplitude images generated.
Provide us with some pictures, opening them into SNAP

wharfbanger · March 1, 2020, 9:36pm

Hello all, I have some questions I hope someone can help with. I understand restituted orbits are available within 24 hours of sensing, and these are automatically used by snap2stamps if the precise orbit data is not available. Does the restituted orbit data provide good results with StaMPS?

I would like to make an experiment to compare results from precise versus restituted orbits. How do I specify restituted orbit files in the snap2stamps workflow? I want to simulate the situation where I do not have the most recent precise orbit data…

For monitoring volcanoes It would be really great if we don’t have to wait 21 days for the precise orbit files!! Thanks, Mark

Abdel · March 4, 2020, 11:38am

Hello, any idea how to update lon/lat coordinates using the residual topographic information of PS estimated during stamps steps ?
I found a good approach here : https://www.mdpi.com/2072-4292/11/11/1258
That uses the equations below :

Theta is the look angle stored in la2.mat as la
Phi is the heading stored in params.mat as heading
And delta H how can i calculate it ?

mdelgado · March 4, 2020, 12:25pm

Hi! Very nice!

I believe that the delta H is the dem error, that should be saved in a mat variable… (I need to check which one or how is called).

Are you thinking to share with the community the script one done?

That would be very useful
Best

Abdel · March 4, 2020, 1:12pm

Of course. You can also add it to the next release of snap2stamps as a geocoding step after stamps.
Let me know about how to find the DEM error as soon as possible.
Thanks,