# Unwrapping problem

Dear all,
I want to get deformation. I used two images with Iw mode and I did like below:

1. Open products
2. Coregister
3. Form the interferogram
4. Deburst
5. Remove Topo Phase
6)Goldstein Filter phase
6. subset my area of interest (because Unwrapping used a lot of memory. the unwrapping fails due to there being not enough memory, then I created a subset of my area of interest and try with SNAPHU again.)
7. Unwrapping

I attached coherence, interferogram and unwrapped results. I do not know I did right or not?
For example, if you look at unwrapped result, I do not know why green area has 124.54? I know this is displacement but is it in cm or meter? I do not know what is the meaning by this number? Why it is so high while we do not have any fringe in that area?

Are these numbers in right side displacements in unwrapped image? If yes, why they are so high in places that we do not have fringes and are so low in area that we have friges like violet area_ 27.84_?

please explain more this part. I can not understand why displacement is so high in places that we do not have fringes_ I imagine when we do not have fringes, then our displacement should be zero_.

We have three different colors (green, orange and violet) in upper part of unwrapped image. Why? I did not get any fringes in those area, then why they have 3 different colours and what are their meaning?

Cheers,
Marjan

Hi

Which the mean value of coherence ???

I did not understand your question but I know, if you have high coherence, then you have good interferogram.

This is right, but in you coherence band I only see of the min and max value! please show me the mean value!

Go to Analysis, then statistics. You will find it honey. Please somebody answer my question:smiley:

This is correct!!!..

@ marjan Didi you succeed in interpretation of the unwrapped phase? I get the same results and I’m still stuck at this point.
What I see in your picture is the unwrapped phase, but I guess you need to convert to displacement using Radar->Interferometric->Product->Phase to displacement and there you have meters as unit.

Unwrapping low coherence areas is counterproductive, you should mask those areas out instead of forcing the unwrapper to unwrap mostly noise.

Dear hriston_bg
Yes, I converted unwrapped results to displacement but the only site that i found about interpretation part is in below. I hope it helps you.
http://vldb.gsi.go.jp/sokuchi/sar/qanda/qanda-e.html
Cheers

@ mengdahl
I’m not able to set mask file for in unwrapping procedure . Any suggestion is welcome.