The perpendicular baseline between these 2 ALOS acquisitions is 2525 m…
That is definitely on the long side given that your area of interest appears to have significant topography. Do you have access to a shorter-baseline pair?
Unfortunately for ALOS 1 I don’t have a shorter baseline pair.
I tried to use ALOS 2 instead because for this one I have a pair with a spatial baseline of 368 m (but still 1 year of temporal baseline), but I had the same problem with the interferogram formation.
I really don’t understand where I’m doing wrong
Thank you for the help
Can you please specify the parameters employed for the coregistration?
Or put here the xml (if any) you used?
I believe as well as @mengdahl that the coregistration needs to be improved. L-band normally has high coherence values. 2km baseline seems fine to me. It may reach even with 8km baseline if I remember my passed eperience with ALOS.
Let us know
Hi mdelgado,
these are the parameters I set for the coregistration step.
thank you for you kind help!!!
As mentioned on my post on 1st August on the thread: Interferogram from Alos palsar 1.1 data
Try to use lower coherence threshold and lower GCP tolerance.
I have used in the past these parameters:
Steps:
- Read master and slave
- Create Stack :
extent: Master
resampling type: Bicubic interpolation
initial offset method: orbit - Cross-correlation
fineRegistrationOversampling: 16
only GCPsonLand: false
gcpTolerance: 0.25
fineRegistrationWindowWidth: 32
fineRegistrationWindowAccAzimuth: 16
fineRegistrationAccRange: 16
rowInterpFactor : 4
InSAROptimixed: true
ApplyFineRegistration: true
fineRegistrationWindowHeight: 64
columnInterpFactor: 4
maxIteration: 10
coarseRegistrationWindowHeigth: 128
numGCPtoGenerate: 10000
coherenceThreshold: 0.6
coherenceRegistrationWindowWidth: 128 - Warp:
interpolationMethod: Cubic convolution (6 points)
warpPolynomialOrder: 1
rmsthreshold: 0.05 - Interferogram:
substractFlatEarthPhase: true
srpPolynomialDegree: 8
srpNumberPoints: 1001
orbitDegree: 5
Please try with this and let us know. I hope this helps
Cheers
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thank you for your time and help!
I tried using the parameters you suggested
but the result was almost the same
…
Can you tell us give us some more info about the filenames?
I may try to process it if I might be able to get the data.
Let us know.
Thank you so much for your time!
the 2 files name are:
0000230545_002001_ALPSRP180270920 --> acquisition date 12 June 2009
0000230545_001001_ALPSRP233950920 --> acquisition date 15 June 2010
sensor: PALSAR
path: 642
frame: 920
mode: FBD
geometry: ascending
Good morning everyone,
here the data I used.
https://drive.google.com/open?id=1et9Ss51WTfeDoeHi_8GwhUPv5smhNFh9
I downloaded them from Jaxa. Using SNAP I still have problems… is it possible that it doesn’t elaborate data from ALOS well? Has anyone used ALOS data successfully yet?
Thank you for your precious help
V.
one year a part will be too long especially in vegetated areas. Try with one two consecutive revisits (about one month apart)
Dear Vileda,
On other thread we have showed that it is possible to do DInSAR with ALOS data. Unfortunately with your pair, I am getting the same results than you.
I will keep trying and I suggest you to do the same.
Please the one who manages to get some result will write here a post.
@lveci, normally L-band should be able to make the work, but for sure @Vileda can follow your advice to see whether other results may come.
Cheers
Ok, just to be sure ALOS data can be well processed. Thank you.
I’m doing some more attemps. If I get positive results I’ll write you.
Thank you again
V.
After some trials I decided to get data with lower temporal baseline as suggested by @lveci. Indeed had better results, but still so much decorrelation due to many factors (highly vegetated area/ Alp forest , among others… )
Hence only in one valley with cities I got some coherence able to provide non-noise phase.
One of the conclusions is that SNAP is able to process ALOS PALSAR 1.1 level, and the second is that your area needs really short temporal baseline to give non-noise results.
I hope this helps. Good luck!
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Thank you very much for your time and help @mdelgado and @lveci !
It is indeed precious.
I’m now downloading data with lower temporal baseline. Let’s hope to get some results for my study area too.
Thanks again.
V.
Hello everyone,
after several attempts using ALOS 1 and ALOS 2 data on SNAP I changed software and processed a couple of images (temporal baseline 1 month) using SARscape.
The result is much better and it provides information even in the areas covered by vegetation.
I can’t get the this result using SNAP on the same couple of images. Interferograms are still too noisy and with low coherence…
I used SNAP a lot to process Sentinel data without any issues. Now I wonder if the program faces some difficulties with ALOS data (downloaded from Jaxa).
Thank you for your time and help!
V.
This is something we need to investigate @lveci @mfitrzyk . Which images exactly are giving you a good result in other software but not in SNAP?
I used couple of ALOS2 images level 1.1, descending geometry.
Master:25/04/2015
Slave: 09/05/2015
I downloaded them from Jaxa.
You can find them here: https://drive.google.com/drive/folders/1GeFYHsRTMWU2FExcSyFGN7Y-xtS33U38?usp=sharing
Thank you for your help!
Could you please try to process the same ALOS 1 as you proposed previously with SARScape so we can compare the 2 software with equal conditions?
Looking forward to it.