Snaphu plugin for SNAP

[samankoar]

Hello everyone

This is my very first try now I am stuck, please help

I did the stage[1] to [8]. I’ve got the ……ifg_deb_dinsar_ML_flt

Then I made a folder (named it “anap_out”)

Next I went to

Interferometric—>Unwrapping—>Snaphu Export

Now I have

coh_IW1_……snafu.hdr

coh_IW1_……snafu.img

Phase_ifg_……snaphu.hdr

Phase_ifg_……snaphu.img

Snafu.conf

UnwPhase_ifg……snaphu.hdr

According to the https://step.esa.int/…./snaphu/ I have to go to

Interferometric—>Unwrapping—>Snaphu-unwrapping

I am there, on the second tab I chose the folder that made above(snap_out)

Here is my question, for the first tab ,Source product, which file should I use?

I chose coh_IW1_……snafu.hdr ,Phase_ifg_……snaphu.hdr,and UnwPhase_ifg……snaphu.hdr but nothing happens. When put a check mark on “Display execution output” and click Run, I got this error

Variable SNAPHU_TOOL_EXE is not set

Variable SNAPHU_EXE is not set

(I am working on iMac)
Thank you for your time

[ABraun]

please have a look at this tutorial: Sentinel-1 TOPS interferometry

[Tamanna]

Hello
I am also facing problem regarding Snaphu.
I export the data and its generate 6 file.
after that i run the command in terminal but it doesn’t read the commnd given in configuration file.

please help me.

[ABraun]

in Linux you have to compile snaphu first. Was snaphu created successfully?

[samankoar]

my issue solved with this, my snaphu on Linux(ubuntu) was not okay.

[samankoar]

thank you for the reference, big help. is there any other nice tutorial on finding displacement on ground surface, I work on earthquake

[ABraun]

I made some more:

• InSAR Displacement mapping with ERS data
• DEM generation with Sentinel-1 - Workflow and challenges
• Sentinel-1 Stripmap Interferometry

Also these are great references:

• ESA 2020 Copernicus Land Monitoring - European Ground Motion Service
• InSAR Principles: Guidelines for SAR Interferometry Processing and Interpretation (ESA TM-19)

[Tamanna]

Thanks for replying,
I am using Mac OS X and install snaphu completely.
Yes, I created snaphu successfully. But it didn’t read the configuration file command.

[BarrowWight]

I have found that using the operation that calls snaphu inside SNAP to not always work. I prefer to call snaphu from the command line. The configuration file that you generated will have the proper command line operation to call (it should be something like "snaphu.exe -f configfile imageFile lineCount. Therefore, my process is:

snaphu Export -> run command line -> snaphu import.

In addition to being able to avoid the issues with calling it from SNAP, you get two other advantages:

1. You can use SNAPHU v2.0, which adds the -S command line parameter. Calling this parameter will run snaphu normally, then run the unwrapped file back through snaphu with only a single tile. This will fix the visible striping where tiles overlap, and does not add much time to the processing.

2. You can then run the snaphu command on every band. Running it through SNAP does not apply if you have a couple different interferometric pairs in the same product (i.e. a pair for day1-day2, a pair for day1-day3, and a pair for day2-day3)

[ABraun]

@BarrowWight

You can use SNAPHU v2.0, which adds the -S command line parameter. Calling this parameter will run snaphu normally, then run the unwrapped file back through snaphu with only a single tile. This will fix the visible striping where tiles overlap, and does not add much time to the processing.

That is great, thank you for mentioning it!

[Tamanna]

When I run snaphu in command line, it doesn’t work properly. Can you tell me what is the reason?

[ABraun]

as I suggested in the other topic, try the MST solver instead the MCF. You can simply modify the config file and run snaphu again. Deleting temporary files is recommended.

[Tamanna]

I tried it but it show this

from last two hours.

[ABraun]

please don’t distribute your questions over multiple topics.
I recommended multi-looking in the other topic (because of the file size) and asked for a screenshot of the interferogram:

How to Install SNAPHU on Mac OSX and Windows for Unwrapping InSAR Images?

depending on the type of deformation, multi-looking might be an option. How does your interferogram look like? 20x20 m will still allow most analyses and significantly reduces the file size. But as I said, the error message was propably not caused by the size.

[Oded]

Hello @ABraun,

I’m familiar with the PS analysis method. It seems that in your work InSAR Displacement mapping with ERS data, the process was carried out on the whole pixels.
Am I getting it right?
If so, what are the adventages and disadventages of this approach?

Thank you,
Oded Horowits

[ABraun]

Differential InSAR (like in the tutorial) is suitable if you have movement between two images and high coherence to measure it. But whenever you want to detect changes over a longer period and vegetation cover decreases phase quality. You get more accurate results (at least you get a better feeling of random phase contributions), but you need excessively more data and the processing is more complex.

[kry_p]

Hi, all. (not sure if this is the right place or I should start a new conversation.)
I was following the interferometry tutorial and successfully installed snaphu. But when trying to run Snaphu Export, the following prompt appears at the bottom left and if I ignore it and go ahead, the same message appears in a new window. Error: [NodeId: Read] The ‘file’ parameter is not set. If I understood correctly, the selected folder must be the same as where the previous outputs are saved? Any help is welcome! Thanks.

[ABraun]

In the Read tab you select the last interferogram you produced in SNAP, not a folder. The directory doesn’t matter at this stage.

[kry_p]

Thanks! Actually I think the problem was more me not restarting the computer after installing the plugin or something of the sort because today I did the same as Friday and didn’t get the same error.

[svijay]

Hi, all.
Not sure if i should ask this in new conversation.
I am trying to perform snaphu unwrapping on snappy and getting following error in last step-

Error on transforming template for parameter 'copyFilesTemplate

The part of code that i am running on python-