Ok, and by ‘will not be exported’, do you mean that neither the snap2stamps script nor the SNAP GUI will begin the export process? Or will they just run indefinitely?
It’s strange because the coreg and ifg images for the first AOI (processed using snap2stamps) seem correct (I just can’t seem to export them).
Can the snap2stamps scripts be modified to use SRTM 1Sec?
I’ve just tried both SRTM 1Sec HGT and Grid in TOPS+ESD Coregistration, and neither seems to work (I get the same “java.lang.NullPointerException” error).
Is it coreg_ifg2run, coreg_ifg_computation, or coreg_ifg_computation_subset that I would need to edit? Although currently I already see SRTM 1Sec in all of these (the following image is from coreg_ifg2run.xml):
If that is already entered, it should make use of the correct one, no need to change then.
Sorry to say this, but snap2stamps is a user-provided tool and ESA takes no warranty that it works under any circumstances. I can’t think of a reason why it fails in this case.
Have you tried to coregister an image pair with BackGeocoding in the GUI for a test?
I understand of course!
I’m currently downgrading from Ubuntu 20.04 to 18.04 (should’ve done already…), as I realize there are issues peculiar to the former.
I’ll see whether that resolves anything.
Following a downgrade from Ubuntu 20.04 to 18.04 LTS, upgrading RAM to 32 gb, and using SNAP v6, snap2stamps has been fully executed.
After running mt_prep_snap, however, I received an initial message after the opener, “matlab: permission denied,” and then the process continued- it’s still underway, but amplitude estimates have now been produced for all 114 images, as have their interferograms. Does that message indicate the results will be erroneous?
No actual error messages have appeared yet (3/9 patches processed). I went ahead and changed the matlab installation folder contents’ permissions to read/write, hopefully that doesn’t mess something up!
This only means that you do not have matlab in the environmental variables which can be found from mt_prep_snap and a starting file will not be created.
However, this can be created within MATLAB while running stamps itself.
Ok- and could any resulting files have been affected?
Also, on a slightly unrelated matter, does the application of TRAIN to snap2stamps PSI make much difference, since only the master APS is estimated (data set of 114 images, including master)?
TRAIN cannot be applied to snap2stamps.
TRAIN is applied together with StaMPS processing, not to snap2stamps. Please do not mixed terms,
TRAIN does not estimate only APS for the master image. I believe you are confused.
Please read TRAIN manual and tutorial so that you will see that TRAIN estimates APS for each of the images, and the different options for it.
can you try to get GMT5SAR?
I think they moved time ago the website.
I have found using google this repo, but not sure is the official one, you better check it:
After I run the python coreg_ifg_topsar py project.conf scripts, my interfergrams are very noisy and has low coherence. What ideas do you have for improving their coherence?In addition, my study area does not have Sentinel-B images.
This is okay (to a certain degree), because PS InSAR will throw away most of the pixels and only continue with those with a stable phase information. Please have a look at these slides which compare a traditional interferogram with PS InSAR phase analysis: Persistent Scatterer InSAR and StaMPS
Coherence cannot be increased technically, it all depends on the amount of vegetation and other surfaces which cause decorrelation.
i’d say so, yes. Most of the interferograms show the same pattern which indicates that the remaining PS are largely free of noise. The interferograms which strongly differ from the rest are probably affected by atmospheric phase contributions, but as long as these are not imposing wrong patterns in the overall result, it should be fine. You can also identify outliers in the time series plots quite well.
Thanks for your good and clear explanation, but how can I identify outliers in the time series plots quite well? I do installed Train package, how can use it for improving noise effects?
You can plot time series if selected point with the ts option. If one date systematically differs from the temporal trend, it’s probably because of atmospheric disturbance.
It seems my patches (9) are incomplete after running mt_prep_snap; they only contain 10 items each and no psver.mat file (as described here SNAP - StaMPS Workflow Documentation).
No errors messages appear (other than the initial ‘matlab: command not found’, which, if I’ve not misunderstood the above, is harmless).
