SNAPHU Unwrapping

ok, good to know! thanks

Hi,
An other way to speedup the unwrapping is to increase the number of processors in the configuration file for snaphu, In my case it was set to 4 by default but when i tried to unwrapped on a 24 core work station using Snaphu/CygWin I increased the number of processors to 20 in the config file and it worked like a dream. You can set it to a higher number in SNAP while exporting to snaphu. You would only be restricted by the physical number of cores on you machine

Regards

Hi Alex,

Were you able to address your problem with the incorrect unwrapped phase output (using IW)? I am facing a similar problem and am curious if you were able to troubleshoot this. Any info would be appreciated!

@katjensen @Alex
The SM mode is used by the sentinel 1 satellite in exceptional cases of emergency and the data in this mode is rarely available. Where IW mode is available for interferometry at global scale

On the previous question of wrong unwrapped phase, you have to use the correct wrapped phase (the one you used as a source for snaphu export) in combination of the unwrapped phase during your Snaphu import step.

Hope this help you

Thanks

Hi,

I have set vmware configuration as follows, but it is taking 4 hours to execute phase unwraping.

could some one let me know how to configure to get complete snaphu unwrapping quickly within one hour.

I am confused to set “No. Of processors and No.of cores per processor” in vmware

My system configuration is

Processor: Core i7-6700 CPU @ 3.4 GHZ
RAM : 8 GB

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Hi ABraun, Thanks for your review.

looking further for your support to get clear many issues with open source software’s.

after unwrapping, while snaphu import i’am getting error in

SNAP as "NodeId: 3-SnaphuImportOp requires at least one product with InSAR metadata. "

and in

NEST 5.1 as “Java.lang.NullPointer exception”.

could you let know the solution if you come across this issue…

what is your input for
1-Read-Phase
2-Read-Unwrapped-Phase
3-SnaphuImport?

Did you successfully run snaphu?

Have a look at the help menu of this module. It is explained what is needed at which step.

I have successfully run the snaphu.

  1. Read-1: Phase HDR
  2. Read-2: Unwrapped Phase HDR

after entering these values then error is coming.

  1. Snaphu Import: I haven’t checked the checkbox.

even if the checkbox checked there is no change in error message…

How to add Insar metadata…here in with SNAP.

For read-1, use the whole last interferogram product before exporting for snaphu. This will probably be a dimap product which you applied topo phase removal or Goldstein phase filtering.

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Hi Luis Veci,

Thanks for your valuable review…

I have given inputs as you said. but I am getting the following error “can not construct data buffer”.

I tried again it is storing the both input files in the result folder, without showing any progress.

could you let me know for further…

Hello all,

I am trying to reproduce the InSAR scene of 2016 Kumamoto Earthquake as the one shown in http://insarap.org/. I’ve used the same product sources (Ascending track 156: 2016-04-08 / 2016-04-20, Perp. baseline -67.3m), only change I’ve made is cropping them to some parts of subswath that covers the earthquake.

The resulted wrapped product I got is quite similar to theirs. However, after doing unwrapping and using phase-to-displacement function, the result is quite strange. The blue blob above the fault (black line, approximately) should be other color as it is a right-lateral earthquake. Thus, I guess I might do something wrong with the unwrapping process.

I’ve used all the default values when processing in S1TBX and snaphu image provided in the tutorial.
Is there any suggestion to improve the unwrapped result?

Regards,

Hello, I got this error using snaphu: “tiles too small or overlap for given input”. Don’t you know what it means? I did diferrent region yesterday and it was OK. Could my interferogram be too small? That is nonsence right? :smiley:

Hi,

I tried to unwrap phase using snaphu, and I got the following error messages:

Assembling tiles
Can’t open file snaphu_tiles_10980/tmptile_UnwPhase_ifg_VV_26Nov2016_20Dec2016.snaphu.img_0_0.2453_regions
Abort

How to solve this problem?
Thanks.

more information is required: What data are you using? Which steps did you apply?
Where is the snaphu export stored? What is the command you called?

Thanks ABraun.

I used SLC products of Sentinel-1 Interferometric Wide swath and the processing software is SNAP. After filtering the differential interferogram by using Goldstein phase filter, I unwrapped the filtered interferogram using snaphu code in linux (virtual machine). In SNAP, I applied “Snaphu Export” and the output files were stored in “shared folder” between windows and virtual machine.
Command line used in linux terminal is from “snaphu.conf” file.

When processing snaphu export, I used default parameters from SNAP.

That sounds right at first.
I wonder a bit about the file name. Is this how it occurs in the snaphu command?

I just copied the snaphu command from “snaphu_conf” file generated by “Snaphu Export” command in SNAP software and I pasted the copied snaphu command in snaphu processing.

All parameters for unwrapping phase in snaphu were generated when the snaphu export process in SNAP.

However, I am so sorry that all files from my processing were already deleted. So, I am difficult to recheck the history of the processing.

For the processing, I followed the tutorial of Sentinel-1 Stripmap interferometry as in this link http://sentinel1.s3.amazonaws.com/docs/S1TBX%20Stripmap%20Interferometry%20with%20Sentinel-1%20Tutorial.pdf

Dear Andreas Braun,

A attached file in this email is a screenshot of my snaphu process,
including snaphu command, result list and error messages. I hope this
picture giving clearer the problem.

Hopefully, I will have solution from you.

Regards

Best Regards,