Surface Subsidence

Thank you so much ABraun.

  • upliftment
  • subsidence
    is it correct sir?

Upliftment (+)
Subsidence (-)
is it correct sir?

This depends on the date of your first and second product. The movement is given between the date of the master and the date of the slave image.

Dear ABraun

This is the final output of around 19 final Terrain corrected displacement stack. But in this final image the upper area is not clear. please check it once.
displacememt_dsp_TC_Stack_new_displacement_final.bmp (3.2 MB)

With snap

this looks pretty blurred indeed. Do the displacement patterns of the single pairs all show this pattern?

Maybe you should only take those pairs with high coherence and clear fringes and leave out the noisy interferograms.

Dear ABraun

@ shishir.manandhar
But I think I figured this out. So basically I terrain corrected 1)Displacement 2)Unwrapped phase.
And then I collocated them (stacked), and then I applied valid pixel expression of coh>0.4 on the displacement. And I believe the result is good. What are your thoughts on this @ABraun? :slight_smile:

I followed above steps for 5 interferograms.

Here i given as shown in above figure.
Valid pixel validation : Unw_Phase_ifg_21Nov2017_27Dec2017_VV_slv1_21Nov2017>0.4

Is it correct for assigning the coherence value >0.4 ?

Then i created for all 5 interferograms in same way, finally stacked.
i want to know the displacement for that i added this displacements using Band Math, using this below command in edit expression.
($26.displacement_VV + $26.displacement_VV_slv2_27Dec2017 + $26.displacement_VV_slv4_20Jan2018 + $26.displacement_VV_slv6_25Feb2018 + $26.displacement_VV_slv8_21Mar2018)/5
but I’m getting this below error, please check it once.

masking by coherence is a good idea. Maybe you should include all displacements and coherence bands in one stack and then create an average coherence first and use this as a final mask (maybe with a lower threshold, because the average will always be lower).

Dear ABraun,
Here i stacked displacement and coherence and unwrap_* and intensity as shown in figure but i’m not getting where i wanna give coh>0.4.

you enter it in the valid pixel expression (remove what is already in there).
But I actually meant to have all coherence bands in one stack so you can calculate an average coherence as well which you can use for the masking of the average displacement.

Dear ABraun,
Here i added coh_IW3_VV_21Nov2017_27Dec2017_slv2_21Nov2017>0.35 in coherence band. as shown in below figure.

Is it correct?

No, you add coherence threshold in the valid pixel expression of the displacement to mask low coherence values.

1 Like

Thank you so much ABraun.

Is it correct?

Yes, like this. But this is only one image pair, right?

Thank you so much sir…
Yes sir, i will forward for all the 20 images stack.

I suggested to do the same with all coherence bands

Ok sir. thank you

I’m interested in the outcome :+1:

I applied coherence for all the displacement bands as shown in above, then stacked all the bands (1+2+…19). But creating the final displacement band in Band Math i’m getting below error.



If i open the final stacked, one displacement band it is giving this below error.