Interferogram from Alos palsar 1.1 data

don’t get me wrong, I also fully aggree on SNAP as my first choice and I don’t want to change this. I just remembered that @EJFielding was able to correctly process ALOS interferograms (here) with ISCE and I recently read that it is now open to all users.
But obviously, there is some technical issue which cannot be solved from the user side, and since @epapadak was asking, I mentioned it.

@mdelgado and @ABraun I agree with both of you.
I do not want to change software either. It is only since last September that I started using SNAP and I really like it.

I was just wondering what someone like you, that are much more familiar with SNAP than me, would do with this issue of shifted DEM if he noticed that there is a relation between the shift and orbit degree interpolation. Would he trust the results from using the highest degree etc

As @mdelgado said “lets the developers to analyse and solve when possible”.

Thank you all for your quick responses!

Keep on SNAPing! :wink:

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For investigating the bug we need access to the products in question as well as the graph(s) that can be used manifest the issue. @lveci @mfitrzyk

Regarding ISCE it is great to see that the software is Open Source, we can perhaps improve the interoperability of SNAP and ISCE in the future. It should be noted that ISCE comes with US export restrictions to embargoed and sanctioned countries. SNAP is open source and freely usable by anyone in any country and on- or off-planet…

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Hello all,

Yes, it is true that we finally got permission to make most of the JPL InSAR Scientific Computing Environment (ISCE) v2 Open Source under an Apache license, but it still has the EAR99 export restrictions required by the US Department of Commerce.

The ISCE software is all command-line based so it is more for advanced users than the much more user-friendly SNAP software GUI. One big advantage of ISCE is the recent addition of ionospheric corrections for the processing of ALOS, ALOS2, and Sentinel-1 data. See our recent preprint of a manuscript in review on the effects of ionosphere on Sentinel-1 for a discussion of the importance of ionospheric corrections at C-band (


This is great to hear! One of the recommendations from Fringe-2017 is that ionospheric correction should be a standard part of SAR processing-chains.

Hi, mdelgado,
I used these parameters you proposed to process three pairs of ALOS-1 datasets, and got totally different results. I think only the results of the quad-pol datasets are acceptable.
Would you please help me to solve this problem? Thank you!
Some info about these pairs and accordingly results (multi-looked phase) are as follows:
quad-pol obtained in 2008:
Perp Baseline: 1114 m
Temp Baseline: 46 days

dual-pol acquired in 2007:
Perp Baseline: -2003 m
Temp Baseline: 46 days

dual-pol acquired in 2010:
Perp Baseline: -1227 m
Temp Baseline: 46 days

Dear ABraun,
Would you please help me with this InSAR problem?


I think it is related to the management and processing of the orbit information stored in ALOS products.
Maybe your interferogram quality increases if you adjust the settings as suggested by mdelgado here: Problems producing interferograms with ALOS

These results were obtained by using these parameters suggested by mdelgado. And I trid some other paramters, I think that the parameters in the step of flat-earth removal were too large, whcich caused these strong fringes, am I right?

yes, unsuitable parameters during the coregistration can be one reason for stripe-like patterns because a small trend superimposes the actual fringes from topography (or deformation).

You mean that these fringe errors caused by the unsuitable parameters in co-registration? So do I need to reduce the parameter value or increase the parameter value then?

I can’t tell exactly. If you used the parameters from mdelgado you probably already used the highest possible values (e.g. for orbit interpolation degree).
Somehow, the coregistration was not exact enough.

You can try nearest neighbor interpolation for the resampling of the slave during the coregistration. This was at least reported to solve parts of this issue some time ago (I can’t find the topic at the moment).
It is worth comparing different configurations of the coregistration (resampling, more GCPs, different polynomials) and their resulting interferograms. Only change one parameter at a time and check if it has an effect on the stripes.

Thank you very much!
I will try!

dear @ABraun i cant download the pdfs even i logged in. Do you have the pdfs?

They are now here: Resources – EO College

yup I found them but I dont know why it is not downloadable.
Is it limited by location?

I don’t think so. Which resource are you trying to download and what error do you encounter?

I’ve worked with sentinel-1 data with DInSAR and PSInSAR methods. I’m trying to do InSAR with ALOS, I just wanted to see the tutorial and the instructions. I followed your instructions for ALOS processing here is my result. Can you check it, please?

I’m trying to download this file: however there is no difference I can download nothing

This tutorial is quite outdated, but you can use this: InSAR Displacement mapping with ERS data

It also refers to stripmap products and the processing is largely the same(no orbit file for ALOS).

Do you know if NEST is still available? NEST 5C?