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.
@Vileda Could you please share how to download ALOS-2 data ? Did you pay for them?
ALOS-2 is commercial but recently there was a reserch announcement where you can apply for free data. The last call was in 2015, so don’t miss the deadline: https://www.eorc.jaxa.jp/en/research/ra/2nd_ra_eo/index.html
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@ABraun Thank you once again for the proper call. I try to keep with deadline .
Dear all,
I tried to process the ALOS 1 couple of images I proposed you before with SARScape but the result wasn’t good as well. There must be some coregistration problems.
But I tried to process another couple of ALOS 1 images and the result was good in SARScape but not in SNAP.
The images have 3 months temporal baseline.
Thank for your interest and help
V.
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I’d like to share what I found in the “ALOS PALSAR Orthorectification Tutorial” by L.Veci
Even after deskewing, the product will have a significant positional error. For missions such as ALOS-1 and ERS where the product timing and orbit data are not accurate enough, it is recommended to use the SAR Simulation Terrain Correction.
The SAR Simulation Terrain Correction works the same as the Rangle Doppler Terrain Correction with the extra steps of simulating an image based on a DEM and then coregistering the simulated image with the input image. Once the DEM and the input product have been accurately matched, the terrain correction using the Range Doppler method can proceed.
I was wondering if it applies to SLC processing.
Dear Vileda,
May I ask you some questions about the InSAR processing of ALOS/PALSAR in SARscape ?
Did you use the default values for the co-registration and flat-earth removal?
Thanks!
May I ask you another question?
This is the phase map of the interfergram of ALOS-1 obtained by SARscape using the default values for co-registration and flat-earth removal. The areas with fringes are forested areas, and the areas with no fringes are water surface. I wonder that whether the interfergram is right?
Thanks!