input reference point is NOT included in the connectComponent

[MaryemBl]

Hello everyone
I'm working with SNAP to produce Mintpy inputs , I use snaphu to generate connected components, it works fine for some ifgram triplets, but not for the others, the error displayed is:

command line: snaphu -G conncomp.img UnwPhase_ifg_VV_27Oct2020_20Nov2020.snaphu.img 1793(tried 495 also)
error : snaphu v1.4.2
extra data in file UnwPhase_ifg_VV_27Oct2020_20Nov2020.snaphu.img (bad linelength?)

The header file:
ENVI
description = {Unwrapped Phase from complex data - Unit: 1}
samples = 1793
lines = 495
bands = 1
header offset = 0
file type = ENVI Standard
data type = 4
interleave = bsq
byte order = 0
band names = { UnwPhase_ifg_VV_27Oct2020_20Nov2020 }
data gain values = {1.0}
data offset values = {0.0}

Can enyone tell why this happened with this ifgram ?

I tried to apply mintpy for triplets with connected components (snaphu -G command worked on them), another error occured, see log file below. my question is : how to choose a reference point when using connected components?

log.txt.txt
Thank you

[hardreddata]

To your second question and ValueError: input reference point is in masked OUT area defined by maskConnComp.h5! you could disable the masking.

mintpy.reference.maskFile      = no

The alternative is to set the reference point to be a location inside the connected component mask.

Cheers.

[Karthi-Wolf]

Hey hiii, I also got the similar error. i got 'input reference point is in masked OUT area defined by maskConnComp.h5!' . can you explain why it happens and how setting mintpy.reference.maskFile = no helps us? Thanks in advance....

[david-ncu2019]

In my experience, only the process of phase unwrapping error correction needs the reference point to be located in maskConnComp.h5.

[Karthi-Wolf]

Okay mr. david, thanks for letting me know.

[david-ncu2019]

Hello everyone,

I have the same issue, which prevents me from correcting my phase unwrapping errors.

When I ran generate_mask.py inputs/ifgramStack.h5 --nonzero -o maskConnComp.h5, the program produced a mask entirely filled with 0.

I don't know why the algorithm did not correct only the selected interferograms and instead ignored the ones that had been excluded after the step modify_network.

[david-ncu2019]

It is really clear that there is something wrong with the interferograms. A clear white line crosses your study area horizontally (inteferograms), and another line cuts vertically through the image (velocity).

[Karthi-Wolf]

Hi mr. david, you are right, after some analysis I gt to know the reason behind the vertical line, it's becasue it's the area that spans over the given DEM file. I gave my bounding box t be inside the DEM, but as we know ISCE takes little extra area to process so the line cross exactly at the longitude 86.00 as my DEM is 84-85 lon (upto 86). you can see it in the 3rd image 2.height. It's my DEM.
So, now I have seen my unwrap phase and unwrap phase wrap , the horizontal line alomost present in all the images. What should I do to get the output?
I very much appreciate your help in this error.

[ditafaith]

Hi Karthi,
Thanks for sharing this issue. I worried about why ISCE processes beyond the area defined by the bounding box?
This condition makes us provide a larger DEM (says 1 degree wider).

Also, you can crop the AOI using MintPy.

[Karthi-Wolf]

Yes, we can do like that thanks for the suggestion and my study area is safer from that. How can i avoid the horizontal line (it's passes through my AOI) i have already dropped around 700+ pairs with the network.minCoherence in network modification step and I am clueless to find the error source!. thanks in advance.

[david-ncu2019]

That horizontal line may unexpectedly come from the process of burst merging. Where is your study area? What bursts did you use to process?

[Karthi-Wolf]

hi mr.david, this is my study area , a eastern coastal town in India.
I have downloaded the whole sentinel image and processed with 'stackSentinel.py -s .....slcs -o .....orbits -d .....dem/dem.wgs84 -b '19.760 19.973 85.718 85.976' -W interferogram -n '1 2 3' -a ......./orbits -c 5 -C NESD -e 0.70 -m 20160101'

[sharkbig]

I've also encountered the same problem, but the way that set the mask file to "no" doesn't work for me.
Thus, I try to assign the reference point manually according to the maskConnComp.h5 file, and successful proceed to the next step.